ORIGINAL_ARTICLE
Inversion of Rayleigh waves group velocity to shear wave velocity structure in the NW Iran
We determined inter station shear wave structure using data from a temporary network of 23 broadband stations in the north west of Iran. Waveforms were used from 230 tele-seismic and regional earthquakes to obtain inter station dispersion curves of the group velocity of the Rayleigh waves. Events in the epicentral distance range of 250 to 3000 km with magnitudes 3.0 ≤ Mw ≤ 7 were used. The individual dispersion curves of the group velocity of Rayleigh waves for each source-station path have been calculated; Then via double-station method we calculated 20 dispersion curves for inter station paths. The group velocities are available in the range of 6-48 sec; in general it is only possible to resolve the parameters of upper mantle and crust. We divided study area to 5 regions, and then we calculated the average dispersion curve in each region. These curves have been used to determine shear wave structure in each region via non-linear Hedgehog inversion method. We need to initial velocity model to start non-linear inversion process, therefore initial model are calculated via linear inversion method.In additional, the obtained velocity models show that crustal thickness in these 5 regions varies between 40 and 56 km. Also the boundary between Upper and Lower crust changes between 12 and 28 km. The results from the non-linear Hedgehog inversion as applied to derived dispersion curves show a crustal thickness of approximately 40 km in the west part of studied area, 56 km in the middle of studied area and 43 km in the western coast of Caspian Sea.Based on obtained results the Moho depth varies from 56 km to 40 km when you move from the middle of study area to western coast of the Caspian Sea. We propose that under thrusting of Caspian Sea basement beneath the Talesh Mountains impresses Moho depth in Talesh zone. But no geological observation prove the under thrusting of Caspian Sea basement beneath the Talesh Mountains, thereforewe cannot be certain about this propose. In other hand, Talesh zone is located in passive continental margin of Caspian Sea; these kinds of margins have complicated structure. We can assume that observed results in Talesh zone have been created by passive continental margin of Caspian Sea. Also we observed a low velocity and warm (probably) anomaly in range of depth 12-22 km beneath the Sahand volcano. We derived attenuation effects of south Caspian basin when periods bigger than 32 seconds of fundamental mode Rayleigh waves propagate across the south Caspian Basin. We used 20 events in along the Apsheron Sill and calculated dispersion curves of these events at our stations. We collected 172 waveforms from used events; we found only 31 fundamental mode waveforms of Rayleigh waves. In other waveforms energy of fundamental mode was diffused and we cannot specify any trend for dispersion. The South Caspian Basin contains one of the thickest sedimentary deposits in the world. In the South Caspian Basin, based on Priestley et.al. (2001), attenuation of surface waves is largely controlled by sediments in the basin. Therefore we guess that our observations about attenuation of the Rayleigh waves are related to sediments in this basin.
https://jesphys.ut.ac.ir/article_58922_c0febf01e013da3f3adb19921d9cdddd.pdf
2017-04-21
1
13
10.22059/jesphys.2017.58922
Crust
Rayleigh Waves
Non-linear Inversion
Dispersion curve
Hedgehog
Reza
Davoudian
davudian_reza@yahoo.com
1
دانشگاه تحصیلات تکمیلی علوم پایه زنجان
AUTHOR
خلیل
متقی
kmotaghi@iasbs.ac.ir
2
دانشگاه تحصیلات تکمیلی علوم پایه زنجان
LEAD_AUTHOR
Farhad
Sobouti
farhads@iasbs.ac.ir
3
دانشگاه تحصیلات تکمیلی علوم پایه زنجان
AUTHOR
Habib
Rahimi
rahimih@ut.ac.ir
4
موسسه ژئوفیزیک، دانشگاه تهران
AUTHOR
Abdolreza
Ghods
aghods@iasbs.ac.ir
5
دانشگاه تحصیلات تکمیلی علوم پایه زنجان
AUTHOR
ثبوتی، ف.، مرتضینژاد، غ. و قدس، ع.، 1393، ساختار لرزهای پوسته در شمالغرب ایران، شانزدهمین کنفرانس ژئوفیزیک ایران.
1
حجازی نوقابی، آ.، 1391، محاسبۀ منحنیهای پاشندگی گروه ریلی با استفاده از نوفههای لرزهای در شمال غرب ایران، پایاننامۀ کارشناسی ارشد ژئوفیزیک، دانشگاه تحصیلات تکمیلی در علوم پایه زنجان.
2
Aftabi, A. and Atapour, H., 2000, Regional aspects of shoshonitic volcanism in Iran: Episodes, 23(2), 119-125.
3
Azizzanjani, A., Ghods, A., Sobouti, F., Bergman, E., Mortezanejad, G., Priestley, K., Madanipour, S. and Rezaeian, M., 2013, Seismicity in the western coast of the South Caspian Basin and the Talesh Mountains, Geophys. J. Int., 195, 799-814.
4
Badal, J., Corchete, V., Payo, G., Pujades, L. T. and Canas, J. A., 1996, Imaging of Shear- wave velocity structure beneath Iberian, Gepphys. J. Int., 124, 591-611.
5
Burk, C. A. and Drake, C. L., 1974, Continental margins in perspective, The Geology of Continental Margins. Eds. C. A. Burk, and C. L. Drake, 1003-9. New York: Springer-Verlag.
6
Chiu, H. Y., Chung, H. Y., Zarrinkoub, M., Mohammadi, S., Khatib, M. and Iizuka, Y., 2013, Zircon U–Pb age constraints from Iran on the magmatic evolution related to Neotethyan subduction and Zagros orogeny, Lithos., 162–163, 70–87.
7
Copley, A. and Jackson, J., 2006, Active tectonics of the Turkish-Iranian Plateau, Tectonics, 25, TC6006, doi: 10.1029/2005TC001906.
8
Dilek, Y., Imamverdiev, N. and Safak, A., 2010, Geochemistry and tectonics of Cenozoic volcanism in the Lesser Caucasus (Azerbaijan) and the peri-Arabian region: collision-induced mantle dynamics and its magmatic fingerprint, International Geology Review, 52: 4, 536 — 578, First published on: 10 November 2009 (iFirst).
9
Herrmann, R. B. and Ammon, C. J., 2002, Computer programs in seismology, surface wves, receiver functions and crustal structure, Department of Earth and Atmospheric Sciences, Saint Louis University, St Louis.
10
Jackson, J., Priestly, K., Allen, M. and Berberian, M., 2002, Active tectonics of the South Caspian Basin, Geophys. J. Int., 148, 214-245.
11
Djamour, Y., Vernant, P., Nankali, H., R. and Tavakoli, F., 2011, NW Iran-eastern Turkey present-day kinematics: results from the Iranian permanent GPS network, Earth and Planetary Science Letters, 307, 27-34.
12
Kadinsky-Cade, C., Barazangi, M., Oliver, J. and Isacks, B., 1981, Lateral variations of high-frequency seismic wave propagation at regional distances across the Turkish and Iranian plateaus, J. Geophy. Res., 86, 9377-9396.
13
Langston, C. A., 1979, Structure under Mount Rainier, Washington, inferred from teleseismic body waves, J. Geophy. Res. 84(B9), 4749-4762.
14
Maggi, A. and Priestly, K., 2005, Surface waveform tomography of the Turkish-Iranian Plateau, Geophys. J. Int. 160, 1068-1080.
15
Mangino, S. and Priestley, K., 1998, The crustal structure of the southern Caspian region, Geophysical, J. Int., 133, 630-648.
16
Masson, F., Anvari, M., Djamour, Y., Walpersdorf, A., Tavakoli, F., Daignieres, M., Nankali, H. and Van Gorp, S., 2007, Large-scale velocity field and strain tensor in Iran inferred from GPS measurements: new insight for the present-day deformation pattern within NE Iran. Geophysical J. International, 170, 436-440.
17
Mohammdi., A., LAk., R. and Hooshmand., H., 2010, Investigation of sedimentary controls on Urmia lake using sedimentological charachteristics of floor deposits (three 100 m Cores), The 1st International Applied Geological Congress, Department of Geology, Islamic Azad University - Mashad Branch, Iran, 26-28 April 2010.
18
Panza, G. F., 1981, The resolving power of seismic surface waves with respect to crustand upper mantle structural models. in: The solution of the inverse problem in geophysical interpretation. Cassinis R. ed., Plenum Publ. Corp., 39-77.
19
Priestley, K. F., Baker, C. and Jackson, J., 1994, Implications of earthquake focalmechanism data for the active tectonics of the south Caspian basin and surrounding regions, Geophys. J. Int., 118, 111-141.
20
Priestley, K. F., Patton, H. j. and Schultz, C. A., 2001, Modeling anomalous surface-wave propagation across the Southern Caspian Basin, Bulletin of seismological society of America, 91(6), 1924-1929, December 2001.
21
Ritzwoller, M. H., Pasyanos, M., Yang, Y., Levshin, A. L. and Shapiro, N. M., 2006, Progress toward broad band ambient noise tomography in Eurasia, Proceedings of the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring, Orlando, FL (Sept 19-21).
22
Shahbazi, H., 2013, Petrogenesis of quaternary Shoshonitic volcanism in NE Iran (Ardabil): implication for postcollisional magmatism, Journal of Geological Research, Volume 2013, Article ID 735498.
23
Taghizadeh, F., Sodoudi, F., Assari, N. and Ghasemi, M. R., 2010, Lithosphere structure of NW Iran from P and S receiver function, J. Seismol, 14,823836. doi:10.1007/s10950-010-9199-2.
24
Zhu, L. P. and Kanamori, H., 2000, Moho depth variation in southern California from teleseismic receiver functions, J. Geophys. Res., 105, 2969-2980.
25
ORIGINAL_ARTICLE
Estimation of earthquake magnitudes using coda duration in Zagros area
Amplitude and duration of seismic signals depend upon recording distance, propagation path of the wave through different media, and geology at the recording site. In addition, amplitude of recorded signals varies according to the P- and S-wave radiation patterns. Influence of these factors on seismic signals has been considered for magnitude computation in many seismic regions (e. g., Michaelson, 1990 and Eaton, 1992). Estimation of earthquake magnitude is a routine task in all seismological observatories. Several magnitude scales are available, based on amplitude measurement of different seismic phases, and/or on total signal duration. Among them, the duration magnitude (MD) is adopted in many regional networks because it provides a rapid and reliable estimate of the earthquake size through a fairly simple procedure based on the measure of the duration of recorded seismograms. Bisztricany (1958) first demonstrated the existence of a relationship between magnitude and duration, and several authors (e.g., Sole’vev, 1965; Tsumura, 1967; Bakun, 1984; Vidal and Munguía, 2005; Hara, 2007; Colomblli et. al., 2014 and among many others) later discussed the use of duration of the recorded seismograms to measure the event size., Lomax and Michelini (2009) proposed a duration magnitude procedure for the rapid determination of the moment magnitude, based on the P-wave recordings at teleseismic distances, which can be applied for tsunami early warning.In this study, the relationship for estimation of earthquake magnitude was derived using the duration of the coda-waves of recorded signals in the Zagros area. Determination of duration magnitude (MD) is a fast and reliable while in other methods it is difficult to read the correct amplitude. In this method as another advantage is no need to correct signals for instrumental effect. In this study more than 3890 records with magnitude in the range of 2 to 5 with epicentral distances less than 200 km were used. The mentioned data is recorded in IIEES seismic network in the period between 2006 and 2013. Location of earthquakes was in the range of 23.59 to 37 latitude and 43.37 to 61.63 longitude. The aim of this study was to determine the relationship between the magnitudes of the duration using the following equation: M_D=a+b.log_10〖τ+c.R+S_c 〗 In which R is the hypocentral distance, 𝞽 is the signal duration, Sc stands for the station correction, and coefficients of a, b, and c must be determined by analysis of regression. Duration was considered as the time elapsed since the first P-wave arrival to the moment when the noise level is reduced to the coda wave amplitude. By comparing the signal amplitude of the noise before the event, the signal end was determined, our conditions were A_(sign-A_noise )/A_noise
https://jesphys.ut.ac.ir/article_58908_faf734027745835a7772a25570f99ba2.pdf
2017-04-21
15
22
10.22059/jesphys.2017.58908
Duration
coda wave
magnitude estimation
estimation relationship magnitude
Habib
Rahimi
rahimih@ut.ac.ir
1
Assistant Professor
LEAD_AUTHOR
samane
asadi
samane.asadi123@ut.ac.ir
2
دانشجو
AUTHOR
مهدی
رضاپور
rezapour@ut.ac.ir
3
موسسه ژئوفیزیک
AUTHOR
روح اله
امیری فر
r.amirifard@iiees.ac.ir
4
دانشجوی دکتری
AUTHOR
Aki, K. and CHouet, R., 1975, Origin of coda waves: source, attenuation and scattering effects. J. Geophys. Res., 80, 3322-3342.
1
Bisztricany, E., 1958, A new method for determination of the magnitude of earthquakes, Geofiz. Kozlemen, 7, 69-96.
2
Castello, B., Olivieri, M. and Selvaggi, G., 2007, Local and duration magnitude determination for the Italian earthquake catalogue. Bull. Seismol. Soc. Am., 97, 128-139.
3
Colomblli, S., Emolo, A. and Zollo, A., 2014, A duration magnitude scale for the Irpinia seismic network, southern Italy, Seismological Research Letters, 85.
4
Del Pezzo, E., Bianco, F. and Saccorotti, G., 2003, Duration magnitude uncertainty due to seismic noise: inferences on the temporal pattern of G–R b-value at Mt. Vesuvius, Italy, Bull. Seismol. Soc. Am., 93, 1847-1853.
5
Eaton, J. P., 1992, Determination of amplitude and duration magnitudes and site residuals from short-period seismographs in northern California. Bull. Seism. Soc. Am., 82, 533-579.
6
Hara, T., 2007, Measurement of the duration of high-frequency energy radiation and its application to determination of the magnitudes of large shallow earthquakes. Earth Planets Space. 59, 227-231.
7
Hermann, R., 1975, The use of duration as a measure of seismic moment and magnitude. Bull. Seismol. Soc. Am., 65, 899-913.
8
Lee, W. H. K., Bennet, R. and Meagher, K., 1972, A method of estimating magnitude of local earthquakes from signal duration. US Geol. Surv. Open-File Rep, 28.
9
Michaelson, C. A., 1990, Coda duration magnitudes in central California: an empirical approach. Bull. Seism. Soc. Am., 80, 1190-1204.
10
Real, C. R. and Teng, T. L., 1973, Local Richter magnitude and total signal duration in southern California. Bull. Seismol. Soc. Am., 3, 1809-1827.
11
Richter, C. F., 1958, Elementary seismology, W. H. Freeman and Co., San Francisco, 758.
12
Sato, H. and Fehler, M. C., 1998, Seismic wave propagation andscattering in the heterogenoues earth, Springer, New York.
13
Sole’vev, S. L., 1965, Seismicity of Sakalin, Bull. Earthq. Res. Inst. Tokyo Univ., 43, 95-102.
14
Vassallo, M. and Cantore, L., 2010, Analisi del rumore sismico, in Metodi e Tecnologie per l’Early-warning Sismico, G. Iannaccone and A. Zollo (Editors), Doppiavoce, 85-115.
15
Vidal, A. and Munguía, L., 2005, A new coda-duration magnitude scale for northern Baja California, Mexico. Geofísc. Int., 44, 11-22.
16
ORIGINAL_ARTICLE
Investigating The Probabilistic Warning Times for The Earthquake Early Warning System (EEWS) On The North Tabriz Fault
In this study the first step toward establishing an earthquake early warning system in the northwestern of Iran has been studied. The area includes populated cities such an Tabriz, Ahar and Khoy. Due to heavy toll in recent years, great economic and social vulnerability of urban areas to earthquake hazards has been important and particularly noticeable. However, there has been little and few progress made in reduce and minimizing the impact of this natural and destructive disaster. While predicting the earthquake with precision is beyond our current knowledge and ability, in order to tackle the potential casualties as a result of destructive earthquakes, an Earthquake Early Warning System can significantly reduce and minimize the possible death toll. Using CDF (Probability Cumulative Distribution Function) this study aims at investigating the extent to which this Earthquake Early Warning System is implemented for the North Tabriz Fault so as to predict the time of On-Site warning time and Regional warning time in a probabilistic manner. To find out the areas and cities subject to risks of earthquakes, earthquake simulation by using stochastic method, the peak ground motion of the earth (PGA), were calculated for the cities of northwest Iran, as a result of these calculations, high- priority areas examined in the study, 15 of the top priorities in terms of seismicity on the basis of strong ground motion (PGA) nature cities such as Khoy, Varzaqan, Sarab, Tabriz, Qarah Zia od Din, Amand, Tekmeh Dash, Osku, Damirchi, Bostan abad, Sufian, Heris, Avin and Khvajeh has been considered and these cities were based of our study. The result of this study shows that the maximum Regional warning time in the cities of Khoy, Qarah Zia od Din, Avin, Bostan abad, Heris, Khvajeh, Sarab, Tekmeh Dash, Varzaqan, Damirchi, Tabriz was calculated 19, 20, 21, 13, 17, 12, 19, 14, 15, 18, 10 seconds respectively. Due to the fact that for the stations close to the epicenter of the earthquake, the creation of Regional warning time only for distant and far objects is possible and implementable; The On-Site warning time for earthquakes close to the targets was measured, as already was clear it is not possible to establish considerable On-Site warning time by for high-risk areas for North Tabriz Fault. It seems that this amount of time (Regional warning time) to set up Earthquake Early Warning Systems in the city of Tabriz where is the fourth largest city of Iran and comprises about 1.4 million inhabitants and one of the largest Iranian industrial cities that the Regional warning time is under 10 seconds, in terms of economy, cost, time and energy, according to the existing station arrangement will not be economical and vital. It has to be mentioned that the warning times were calculated using the existing seismic network geometry in the region. We calculated the warning times to at least some of the affected population and cities 15 of the top priorities in terms of seismicity on the basis of strong ground motion) in damaging and destructive earthquakes.
https://jesphys.ut.ac.ir/article_60285_f6dd5f7b310befbfa261b00204802df2.pdf
2017-04-21
23
32
10.22059/jesphys.2017.60285
Earthquake Early Warning Systems
Onsite Warning and Regional Warning
Peak Ground Motion of the earth
Probability Cumulative Distribution Function (CDF)
Homeyra
Karimi Vahed
karimi_vahed@yahoo.com
1
master student at Islamic Azad University, Science and Research Branch, Tehran
AUTHOR
Reza
Heidari
r.heidari61@gmail.com
2
Department of Geophysics, Science and Research Branch, Islamic Azad University, Tehran, Iran
LEAD_AUTHOR
میرزائی، ن.، 1381، پارامترهای مبنایی زمینلرزههای ایران، دانش نگار، تهران– ایران.
1
Allen, R.M., P. Gasparini and O. Kamigaichi, 2009, Earthquake Early Warning, Special Issue, Seismo. Res. Lett., 80(5), 682-782.
2
Ambraseyes, N. N. and Melville, C. P., 1982, A history of Persian earthquakes, Cambridge university press, Cambridge, 219 pp.
3
Ashtari, M., Hatzfeld, D. and Kamalian, N., 2005, Microseismicity in region of Tehran: Tectonophysics, 395, 193-208.
4
Atkinson, G. M. and Boore, D. M., 1995, Ground motion relations for Eastern North America, Bulletin of the Seismological Society of America, 85(1), 17-30.
5
Atkinson, G. M. and Boore, D. M., 1998, Evaluation of models for earthquake source spectra in Eastern North America, Bulletin of the Seismological Society of America, 88(4), 917-934.
6
Berberian, M. and Arshadi, S., 1976, On the evidence of the youngest activity of the north Tabriz fault and the seismicity of Tabriz city, Geol. Surv., 39, 397-418.
7
Boore, D., 1983, Stochastic simulation of high-frequency ground motions based on seismological models of the radiated spectra, Bulletin of the Seismological Society of America, 73, 1865-1894.
8
Boore, D. M. and Atkinson, G. M., 1987, Stochastic prediction of ground motion and spectral response parameters at Hard-Rock sites in Eastern North America, Bulletin of the Seismological Society of America, 77(2), 440-467.
9
Boore, D., 2003, Simulation of ground motion using the stochastic method., Pure appl. Geophys, 160, 635-676 0033-4553/03/040635 -42.
10
Cooper, J. D., 1868, Earthquake indicator, Evening Bulletin XXVII, 23.
11
Espinosa-Aranda, J., Jimenez, A., Ibarrola, G., Alcantar, F. and Aguilar, A., 1995, Mexico city seismic alert system, Siesmic Res, Lett, 66(6), 42-53
12
Motazedian, D. and Atkinson, G., 2005, Stochastic finite fault modeling based on dynamic corner frequency, Bulletin of the Seismological Society of America, 95, 995-1010.
13
Motazedian, D., 2006, Region-specific seismic parameters for earthquakes in northern Iran, Bulletin of the Seismological Society of America, 96, 1383-1395.
14
Nakamura, Y., 1988, On the urgent earthquake detection and alarm system (UrEDAS), Proceeding of the 9th world conference on Earthquake Engineering, VII, 673-678.
15
Moradi, A., Hatezfeld, D. and Tatar, M., 2011, Microseismicity and seismotectonics of the North Tabriz fault Iran, Tectonophysics.
16
Wells, D. and Coppersmith, K., 1994, New empirical relationship among magnitude, rupture width, rupture area, and surface displacement, Bulletin of the Seismological Society of America, 84, 974-1002.
17
Shahvar. M. P., Zare, M. and Castellaro, S., 2013, A unified seismic catalog for the Iranian Plateau, Seismological Research Letters, volume 84, November 2, March/April 2013 233.
18
ORIGINAL_ARTICLE
the effects of large Earthquake on the excitation of polar motion and the change in length of day
In this study, the effects of Earthquake on the excitation of polar motion and the changes in the length of day are investigated. To do so, at first the deformation resulting from Earthquake is computed and then, its effects on the polar motion and length of day are derived. The geodynamic model which determines the crustal deformation is Dahlen's model in which the effects of Earthquake deformation coupled with the rotational motion of the Earth. For this purpose, it is assumed that the Earth is a spherical symmetric, isotropic, elastic and homogeneous media and the Earthquake is caused by the dislocation discontinuities on fault surface. In this case, the solution of the corresponding boundary value problem determines the deformations of the Earth due to Earthquake. On the other hand, the rotational motion of the Earth as a deformable body is governed by the Liouville equation, which determines the motion of polar axis under the applied external torque. Since the polar motion is investigated, only the homogeneous solution of the latter equation must be determines. In this case the solution of Liouville equation is only dependent on the moment of inertia of the Earth. Since, the components of the Inertia tensor of the Earth are dependent on the shape of the earth and its density distribution, and in this case, the Earth undergoes a shape change, therefore, its moments of inertial are no longer constant and depend on the deformation of the Earth. By computing the deformation results from the Earthquake as discussed at the first step, one may derive shape change and changes in the density distribution of the Earth from which, the changes in the component of inertia tensor may be obtained. Finally, the changes in the inertial tensor through Liouville equation can lead to the excitation of polar motion or the variations in the length of day, which determine by the solution of the corresponding equation. The simulated problems in two cases of strike-slip and dip-slip faults reveal that the amplitude of excitation due to strike-slip fault is maximum at equator and decrease toward poles and it is zero at pol. However, in the dip-slip fault, the amplitude at mid-latitude regions is maximum and is zero at both equator and poles. The variation in the length of day is zero at poles and is maximum at equator for strike-slip fault. For dip-slip fault, it is zero at both equator and poles and is maximum over the mid-latitude regions. Moreover, using the geometric parameters of the large Earthquakes from Harvard Earthquake Catalogue, occurred during the period of 1976 to 2014, their effects on the polar motion and length of day are studied within the adapted geodynamical model. The results show that among the selected Earthquakes, the 2011 Japan Earthquake had had the most significant effects on the motion of polar axis and the length of day .This excitation is in westward direction. The combined impact of all Earthquakes is also computed which clarifies that the polar excitation is increasing in the X direction (prime vertical component) and decreasing in the direction of Y (meridian component). For the validation of our results, we use the data of IERS (International Earth Rotation Service) which shows a relatively good agreement.
https://jesphys.ut.ac.ir/article_60280_77e0a5653a8b6f792605abd42c9fd36a.pdf
2017-04-21
33
51
10.22059/jesphys.2017.60280
Deformation
dislocation theory
Dahlen's model
Polar motion
Large earthquake
مهدی
روفیان نایینی
mraoofian@kntu.ac.ir
1
هیات علمی دانشگاه صنعتی خواجه نصیرالدین طوسی
LEAD_AUTHOR
رضا
عرب صاحبی
r.arabsahebi@mail.kntu.ac.ir
2
دانشگاه صنعتی خواجه نصیر
AUTHOR
C. Xu, Sun, W. and Zhou, X. 2013, Effects of Huge earthquakes on Earth rotation and the length of day, Terr. Atmos. Ocean. Sci, 24(4), Part 1, 649-656.
1
Cecchini, G., 1928, II problema della variazione delle latitudini, Publ. Reale Obs. Astr. Brera in Milano, 61, 7-96.
2
Chao, B. F. and Gross, R. S. 1987, Change in the Earth’s Rotation and Low-degree Gravitational Field Induced by Earthquake, Geophys, J. Roy. Astron. Soc., 91, 569-596.
3
Chao, B. F. and Gross, R. S., 1995, Changes in the Earth’s rotation energy induced by earthquakes, Geophys, J. Int., 122, 776.
4
Dahlen, F. A., 1971, The excitation of the Chandler wobble by earthquakes, Geophys. J. Int., 25, 157-206.
5
Dahlen, F. A., 1973, A correction to the excitation of the Chandler wobble by earthquakes, Geophys. J. R. Astr. Soc., 32, 203-217.
6
Degryse, K. and Dehant, V., 1996, Are earthquakes responsible for the excitation of the FCN and/or of the FICN? Phys. Earth Planet. Inter., 94, 133-143.
7
Gross, R. S. and Chao, B. F., 2006, The rotational and gravitational signature of the December 26, 2004 Sumatran earthquake. Surv. Geophys., 27, 615-632.
8
Gross, R. S., 1986, The influence of earthquakes on the Chandler wobble during 1977-1983. Geophys. J. Int., 85, 161-177.
9
Gross, R. S., 2011, Japan quake may have shortened Earth days, moved axis, JPL department of NASA News.
10
Gu, Z. N., 1996, The study of excitation of the earthquake to Earth’s rotation, Earth Moon Planet, 74, 35-47.
11
Jeffreys, H., 1916, Causes contributory to the annual variation of latitude, Mon. Not. R. astr. SOC., 76, 499-525.
12
Mansinha, L. and Smylie, D. E., 1967, Effect of earthquakes on the Chandler wobble and the secular polar shift, J. geophys. Res., 72, 4731-4743.
13
Munk, W. and MacDonald, G., 1960, The rotation of the Earth, a geophysical discussion, Cambridge University Press, 323 pp.
14
Nilsson, T., Bohm, J. and Schuh, H., 2010, Impacts of the 2010 Chile earthquake on Earth rotation, AGU Spring Meeting, Foz do Iguau, Brazil, August 08-12, 2010.
15
O’Connell, R. J. and Dziewonski, A. M., 1976, Excitation of the Chandler wobble by large earthquakes, Nature, 262, 259-262.
16
Rice, J. R. and Chinnery, M., 1970, On the calculation of changes in the Earth’s inertia tensor due to faulting, Geophys. J. R. aster. Soc., 29, 79-90.
17
Smith, M. L., 1977, Wobble and nutation of the Earth. Geophys. J. Int., 50, 103-140.
18
Vanicek, P. and Krakiwsky, E. J., 1986, Geodesy the Concepts, 2nd corrected edn, North Holland, Amsterdam.
19
ORIGINAL_ARTICLE
Detective of stratigraphic trap of Sarvak formation using petrophysical logs and seismic attributes in one of the oil fields in the south west of Iran
Nowadays there are many attempts to exploring stratigraphic traps all over the world. Because of existing Sarvak reservoir rock Formation in central Persian Gulf which consists of carbonate with various lateral changes in the terms of lithology, there is high probability to form of these stratigraphic traps in this region. The main aim of this research is to recognize the oil and gas stratigraphy traps by using seismic attributes and petrophysical and geological logs in the Bahregansar oil field, NW of Persian Gulf basin. In order to reconnaissance these regions, petrophysical logs (density, acoustic, neutron and gamma) and seismic reflection data from three wells have been studied. On the other hand, the obtained data have been interpreted with some seismic volume attributes such as momentary frequency, domain and acoustic impedance, reflection coefficient, normalized amplitude and envelope amplitude attributes to show the situation of hydrocarbon basin in the study area. By using seismic attributes and compare with geological information we can infer reliable interpretation because of some reasons. The first reason is seismic velocity allow us to understand the situation of lithology, fluid content and abnormal pressure or temperature. The second reason is lateral amplitude changes permit the inference of geological situation such as changes in porosity, existence of hydrocarbon and thickness of lithology. The third reason is seismic trace morphologies or interpretation sections allow us to recognize depositional environments or faults and fractures. Finally, changes in measurements direction permit to deduce velocity anisotropy, or fracture orientation. The software which used in this study was Petrel. Density log is creating with using neural network method by application of well No.3 in this oil field. The petrophysical study of gamma log shows well identity of formation boundaries in sections. Also the use of cross plot graph of density-neutron logs applied to well recognized of the efficient zones in Gurpi-Ilam, Sarvak and Kazhdumi-sand Formation. The Turonian epirogenic event is caused erosion of top of the Sarvak Formation and on the other hand Santonian epirogenic is caused hiatus stratigraphic trace in the lower part of Gurpi and Ilam Formation. By seismic volume attributes interpretation a number of the stratigraphy traps detected over some seismic sections. Furthermore, recognizing a main fault which exists in the western part of Hendijan oil field has main role in the changing of lithological effect in continuity quality of seismic reflection. In order to increase interpretation accuracy, some seismic inversion has been made on considered sections and the obtained data have been compared with petrophysical logs and seismic attributes. By doing this research and interpretation of sections two type of stratigraphic traps recognized. The first type is oil trap related to the top of Turonian unconformity (truncation) which exists in the eastern part of fault. The second is relation to narrowing part which is belonging to the above of the reservoir layer (pinch out) under Turonian unconformity in the western part of seismic section. Meanwhile the study shows that there is an oil trap as hydrocarbon accumulation in the upper part of Kazhdumi sand formation seismic subunit acting like stratigraphy trap in the above unconformity. In general, all of oil traps recognized in this study were composed of anticline structural dip and on the other hand existence of faults has a main role of geological structure in this region. The obtained results clearly demonstrated the shape and the geological situation of the existing structural traps in the studied area.
https://jesphys.ut.ac.ir/article_59029_20ae56a80f55d46a383d52c4b2dad17a.pdf
2017-04-21
53
69
10.22059/jesphys.2017.59029
seismic attributes
Sarvak Formation
Petrophysical logs
Petrel software
Stratigraphic trap
Unconformity
Ramin
Nikrouz
r.nikrouz@urmia.ac.ir
1
Urmia University
LEAD_AUTHOR
َAliasghar
Siabeghodsy
a.siabeghodsy@urmia.ac.ir
2
دانشگاه ارومیه
AUTHOR
پروین
حسنعلی زاده
ph1232@yahoo.com
3
دانشگاه ارومیه
AUTHOR
آقچهلو، م.، شاهوار، م. و علیمحمدی، ن، 1385، لرزهنگاری در اکتشاف نفت، اندیشکده اعتلای صنعت نفت، مقاله: 34
1
رضایی، م. ر.، 1384، زمینشناسی نفت، انتشارات علوی.
2
رحیمی، م.، 1384، کاربرد چینهشناسی لرزهای در اکتشاف نفتگیرهای چینهای خلیج فارس، م. اکتشاف و تولید، شماره 24.
3
روستایی، س.، شکرانه، ف.، رحیم پور بناب، ح. و کدخدایی ایلخچی، ع.، 1388، کاربرد نمودار انحراف سرعت در تعیین نوع تخلخل و روند تراوایی در میدان گازی پارس جنوبی، مجله اکتشاف و تولید، شماره 56.
4
محمدی، م. ح.، 1378، گزارش تکمیلی چاه هندیجان شماره 6، مدیریت اکتشاف، اداره کل زمینشناسی.
5
مختاری، م.، 1380، مبانی لرزهنگاری و کاربرد آن در علوم زمین، انتشارات کتاب مرو، مشهد.
6
مسی بیگی، م. و باصره، م.، 1389، ارزیابی پتروفیزیکی و زونبندی سازندهای کنگان و دالان در چاه اکتشافی بندو بست -1 با استفاده از نگارهای چاه پیمایی، م. اکتشاف و تولید، شماره 73.
7
معمارضیاء، ع.، 1385، لرزهنگاری سهبعدی (اصول و مفاهیم)، چاپ اول، شرکت نفت فلات قاره ایران، مدیریت طرحهای اکتشافی.
8
Abdollahie Fard, I., Braathen, A., Mokhtari, M., Alavi, S. A., 2006, Interaction of the Zagros Fold-Thrust Belt and the Arabian-type, deep-seated folds in the Abadan Plain and the Dezful Embayment, SW, Iran, Petroleum Geophysics, 12, 347-362.
9
Aliee, M. H., 2005, Hendijan oil field, 2D seismic study and seismic inversion, Report Number: GR 2073, N.I.O.C.
10
Armstrong, T., 2001, Velocity anomalies and depth conversion-drilling success on Nelson Field, Central North Sea, 63rd EAGE Conference & Exhibition, Expanded Abstracts, IV-2.
11
Asadabadi, A., 2005, Hendijan full field reservoir study, Phase 2: Reservoir characterization report, N.I.O.C.
12
Bartel, D. C., Busby, M., Nealon, J. and Zaske, J., 2006, Time to depth conversion and uncertainty assessment using average velocity modeling, 76th SEG Annual Meeting, Expanded Abstracts, 2166-2169.
13
Beydoun, Z. R., 1995, Productive Middle East clastic oil and gas reservoir: their depositional setting and origins of their hydrocarbons, American University of Beirut, Lebanon, Spec. Pub. Int. Ass. Sediments, 22, 331-345.
14
Cameron, M., Fomel, S. and Sethian, J., 2008, Time-to-depth conversion and seismic velocity estimation using time-migration velocity, Geophysics, 73, VE205-VE210.
15
Chambers, R. L. and Yarus, J. M., 2002, Quantitative use of seismic for reservoir characterization, CSEG Recorder, June, 14-25.
16
Chen, Q. and Sidney, S., 1997, Seismic attribute technology for reservoir forecasting and monitoring, The Leading Edge, 16, 445-456.
17
Chopra, S. and Marfurt, K. J., 2005, Seismic attributes – A historical perspective, Geophysics, 70, 3-28.
18
Ghazban, F., 2007, Petroleum geology of the Persian Gulf, Published by Tehran University.
19
Hassanzadeh, A. J, Nabi-Bidhendi, M., Javaherian, A. and Pishvaie, M. R., 2006, Integrated seismic attributes to characterize a widely distributed carbonate clastic deposit system in Khuzestan Province, SW Iran. Journal of Geophysics and Engineering, 6, 162-171.
20
I.O.O.C (Iranian Offshore Oil Co.), 2005, Bahregansar Geosciences Study.
21
Ishwar, N. B. and Bhardwaj, J. A., 2013, Petrophysical well log analysis for hydrocarbon exploration in parts of Assam Arakan Basin, India, 10th Biennial International Conference and Exposition, Kochi, Kerala, India.
22
Raeesi, M., Moradzadeh, A., Doulati Ardejani, F. and Rahimi, M., 2012, Classification and identification of hydrocarbon reservoir lithofacies and their heterogeneity using seismic attributes, logs data and artificial neural etworks, Journal of Petroleum Science and Engineering, 82-83, 151-165.
23
Rezvandehy, M., Aghababaei, H. and TabatabaeeRaissi, S. H., 2011, Integrating seismic attributes in the accurate modeling of geological structures and determining the storage of the gas reservoir in Gorgan Plain (North of Iran), Journal of Applied Geophysics, 73(3), 187-195.
24
Selly, R. C., 1985, Ancient sedimentary Environment, 3rd edition, Chapman & Hall.
25
Sheriff, R. E., 1989, Seismic stratigraphy, Springer Publisher.
26
Sherkati, S. and Letouzey, J., 2004, Salt movement, tectonic events and structural style, in the central Zagros fold and thrust belt, Iran, 6th Middle East Geosciences Conference, GEO 2004, GeoArabia.
27
Suardana, M., Samodra, A., Wahidin, A. and Rachmat Sule, M., 2013 , Identification of fractured basement reservoir using integrated well data and seismic attributes: case study at Ruby Field, Northwest Java Basin , Search and Discovery Article, AAPG Annual convention and exhibition, Pittsburgh, Pennsylvania, May 19-22.
28
Taner, M. T., 2001, Seismic attributes, Canadian Society of Exploration Geophysicists Recorder, 26(9), 48-56.
29
ORIGINAL_ARTICLE
Improvement In Depth And Structural Index Estimation Of Potential Field Sources By Using Curvature Attributes
Interpretation of potential field data generally is quantitative or qualitative. An important factor in the issue of interpretation is how much interpreter is confident on data that provides the information needed to achieve the objectives of the study. Reliance on interpretation can be increased by the use of effective methods for parameters determination of causative sources. Although in most of methods not required to know the density or susceptibility contrast, but these methods are based on the assumption that the source is a certain type (horizontal slab, vertical dykes, etc.) and in two-dimension. By selecting the wrong type of sources, large errors may occur. Despite all these problems, numerous automatic techniques are designed that can be applied over the magnetic or gravity anomalies to quickly estimate the depth of sources.Curvature method is used to analyze and interpretation of potential field anomalies. Potential field anomalies can be transformed into special functions that formed peaks and ridges over isolated sources. All of these special functions have a mathematical form over sources that lead to a common equation to estimate the depth of the source from the peak value and curvature at the peak. Curvature attributes that used at this case called most negative curvature. Special functions are divided into two categories: Model-specific special functions and Model-independent special functions. Model-specific special functions usually are calculated from a transformed potential field for locating of specific sources such as a vertical magnetic contact, vertical density contact, etc. The horizontal gradient magnitude (HGM) and observed potential field (absolute value) are two types of model-specific special functions that formed ridges over specific sources. Model-independent special functions are used to calculate locations for various types of sources from the observational or modified potential field. Total gradient (TG), also called the analytic signal, and local wavenumber (LW) fall into this group.Usually, special functions need that the potential field undergoes a transformation, such as reduction-to-pole and vertical derivative. For gridded data, eigenvalues of the curvature matrix associated with quadratic surface is fitted to a special function within 3×3 window, to locate and estimate the depth of sources. Another curvature attributes is shape index that quantitatively stated the local shape in terms of bowl, valley, flat, ridge and dome. Shape index attribute (SHI) and Geometry factor provide a way to easily reject some of invalid estimations.In this study, method of curvature attributes has been applied on noisy and noise free synthetic data by using Model-specific (HGM and absolute value) and Model-independent special functions (Total gradient and local wavenumber). Finally, this method was tested on real data from Mobrun massive sulfide ore of Canada by using special functions of two models and was estimated a structural index (SI) from local wavenumber special function for the mine. The results of estimating the depth by this method had a good match with the results of the boreholes. Finally, the depth results of this method were compared with Euler deconvolution method which shows that method of using curvature attributes is more accurate in depth estimation.
https://jesphys.ut.ac.ir/article_57739_9b68b92a6893f2cd06132df1952cb74a.pdf
2017-04-21
71
86
10.22059/jesphys.2017.57739
Potential Field
Curvature
Special function
Quadratic surface
depth estimation
محمد
برازش
barazeshm@ut.ac.ir
1
دانشجو کارشناسی ارشد موسسه ژئوفیزیک دانشگاه تهران
AUTHOR
Seyed Hani
Motavalli Anbaran
motavalli@ut.ac.ir
2
عضو هیات علمی موسسه ژئوفیزیک دانشگاه تهران
LEAD_AUTHOR
Abbas, M. A., Fedi, M. and Florio, G., 2014, Improving the local wavenumber method by automatic DEXP transformation, Journal of Applied Geophysics, 111, 250-255.
1
Barraud, J., 2013, Improving identification of valid depth estimates from gravity gradient data using curvature and geometry analysis, First break, 31(4).
2
Beiki, M., 2010, Analytic signals of gravity gradient tensor and their application to estimate source location, Geophysics, 75(6), I59-I74.
3
Beiki, M. and Pedersen, L. B., 2010, Eigenvector analysis of gravity gradient tensor to locate geologic bodies, Geophysics, 75(6), I37-I49.
4
Cordell, L. and Grauch, V., 1982, Mapping basement magnetization zones from aeromagnetic data in the San Juan Basin, New Mexico, 1982 SEG Annual Meeting, Society of Exploration Geophysicists.
5
Essa, K. S., 2012, A fast interpretation method for inverse modeling of residual gravity anomalies caused by simple geometry, Journal of Geological Research 2012.
6
Grant, F. S. and West, G. F., 1965, Interpretation theory in applied geophysics, McGraw-Hill Book.
7
Hansen, R. and Deridder, E., 2006, Linear feature analysis for aeromagnetic data, Geophysics 71(6), L61-L67.
8
Nabighian, M. N., 1972, The analytic signal of two-dimensional magnetic bodies with polygonal cross-section: its properties and use for automated anomaly interpretation." Geophysics, 37(3), 507-517.
9
Phillips, J. D., Hansen, R., O. and Blakely, R., J., 2007, The use of curvature in potential-field interpretation, Exploration Geophysics, 38(2), 111-119.
10
Pilkington, M. and Keating, P., 2005, The relationship between local wavenumber and analytic signal in magnetic interpretation, Geophysics, 71(1), L1-L3.
11
Roberts, A., 2001, Curvature attributes and their application to 3D interpreted horizons, First break, 19(2), 85-100.
12
Roest, W. R. and Pilkington, M., 1993, Identifying remanent magnetization effects in magnetic data, Geophysics, 58(5), 653-659.
13
Roest, W. R., Verhoef, J. and Pilkington, M., 1992, Magnetic interpretation using the 3-D analytic
14
signal, Geophysics, 57(1), 116-125.
15
Roy, L., Agarval, B. N. P. and Shaw, R. K., 2000, A new concept in Euler deconvolution of isolated gravity anomalies, Geophysical prospecting, 48(3), 559-575.
16
Salem, A., Ravat, D., Smith, R. S. and Ushijima, K., 2005, Interpretation of magnetic data using an enhanced local wavenumber (ELW) method, Geophysics, 70(2), L7-L12.
17
Smith, R. S., Thurston, J. B., Dai, T. and MacLeod, I. N., 1998, iSPI TM—The improved source parameter imaging method, Geophysical Prospecting, 46(2), 141-151.
18
Telford, W. M., Geldart, L. P. and Sheriff, R. E., 1990, Applied geophysics, Cambridge university press.
19
Thompson, D., 1982, EULDPH: a new technique for making computer-assisted depth estimates from magnetic data, Geophysics, 47(1), 31-37.
20
Thurston, J. B. and Smith, R. S., 1997, Automatic conversion of magnetic data to depth, dip, and susceptibility contrast using the SPI (TM) method, Geophysics, 62(3), 807-813.
21
ORIGINAL_ARTICLE
Novozhilov Mean Rotation as a scalar earth surface deformation measure in local scale
(Case study: N-W of Iran)
The regions of northwestern Iran, eastern Turkey and Caucasus are one of the most intriguing regions of the Arabia-Eurasia collision. It is a pure intercontinental collision zone with the highest elevation in western Asia. This region is known for a spatial separation of sub-parallel thrusts and strike-slip faults. Iranian plateau includes two major mountain belts, hence Alborz in the north and Zagros in the south and west of Iran. Azerbaijan includes Alborz mountains, Talesh and Lesser Caucasus along with mountains in the Azerbaijan plateau. Azerbaijan is between great mountains of Caucasus in the north and Alborz in the east and distance away from Zagros in the south. A lot number of faults including Tabriz fault and Aras fault meet in the west of the study area. One of the most fundamental and important a new area of research in geodesy is earth surface deformation modeling at local and global scales. Also, check out the effective factors in deformation, and offers various computation methods in order to determine the movement of the earth's crust are considered as a recent development in geodesy. In recent years, space geodetic techniques with high precision and reliability have provided new sources of information to determine the geodetic positions. This information used for the detection and quantification of surface deformations. In this paper, Novozhilov method has been studied for mean rotation calculation with finite difference approach on earth surface in N-W of Iran especially north Tabriz fault. To achieve this goal, linear strain and rotation tensors on earth surface based on shell theory in continuum mechanics will be calculated using finite difference approach and then the mean rotation is extracted using linear strain and rotation tensors. Finite difference method is numerical methods based on mathematical discretization of the equations of boundary problems. By using this method, continuous process is studied in a finite number of sufficiently small time intervals. So it is possible, in these small intervals, the function approximated by approximate expressions. In each elementary interval is the integration, with the results of integration in the previous interval are taken as initial for the next time interval.In the fourth decade of the 20th century Novozhilov obtained a measure of the mean rotation by modifying a previous definition produced by Cauchy. In the literature, this measure has been named Novozhilov's mean rotation measure ever since. The measure introduced by Novozhilov for the mean rotation indicates the importance of the infinitesimal rotation tensors. The results obtained from linear strain and rotation tensors that computed using geodetic observations (GPS) in 2005, have good agreement with the results of previous work. The results of Novozhilov’s mean rotation criteria in the part of the Azerbaijan plateau shows that the highest right turn rotation is related to YKKZ station (2.975±0.631deg/Myr). An important feature of Novozhilov’s mean rotation analysis on earth surface than analysis of this parameter in Cartesian system is that the results of this measure on earth surface is very close to the results of previous studies on blocks rotation in different areas in Iran. Accuracy of this measure on earth surface is acceptable in most parts of the case study.
https://jesphys.ut.ac.ir/article_60281_df5e7e004cd50f657280864e6d184772.pdf
2017-04-21
87
99
10.22059/jesphys.2017.60281
Earth surface deformation analysis
Strain tensor
Rotation tensor
Mean Rotation (Novozhilov)
Finite difference
Rahim
Javadi Azar
rahim_javadi136@email.kntu.ac.ir
1
Faculty of Geodesy and Geomatics Eng., K. N. Toosi Univ. of Tech., Tehran, Iran
AUTHOR
Behzad
Voosoghi
vosoghi@kntu.ac.ir
2
Faculty of Geodesy and Geomatics Eng., K. N. Toosi Univ. of Tech., Tehran, Iran
LEAD_AUTHOR
Mir Reza
Ghaffari Razin
mr.ghafari@arakut.ac.ir
3
دانشگاه صنعتی خواجه نصیرالدین طوسی دانشکده نقشه برداری گروه ژئودزی
AUTHOR
جعفری، م.، 1388، بررسی و تعیین تغییرات انحنای پوسته زمین در ایران بوسیله مشاهدات GPS، پایاننامه کارشناسی ارشد ژئودزی، دانشکده نقشهبرداری، دانشگاه خواجهنصیرالدینطوسی.
1
جمور، ی.، موسوی، ز.، نانکلی، ح.، صدیقی، م. و توکلی، ف.، 1386، برآورد اولیه میدان سرعت و استرین از شبکه دائمی GPS ایران برای اهداف ژئودینامیک(IPGN)، اولین همایش پیش نشانگرهای زلزله، 15 اسفند 1386، مرکز مطالعات پیشنشانگرهای زلزله مؤسسه ژئوفیزیک.
2
درویشزاده، ع.، 1372، زمینشناسی ایران، انتشارات نشر دانش امروز.
3
رئوفیان نایینی، م.، 1387، برآورد تنسور کرنش در شبکه ژئودینامیک کشور، پایاننامه کارشناسی ارشد ژئودزی، دانشکده فنی، دانشگاه تهران.
4
زارع، م.، 1380، خطر زمینلرزه و ساخت و ساز در حریم گسل شمال تبریز و حریم گسلش گسلهای زمین لرزهای ایران، پژوهشنامه زلزلهشناسی و مهندسی زلزله، سال چهارم، شماره دوم و سوم، تابستان و پاییز 1380، صص 46-57.
5
زمانی قره چمنی، ب.، 1390، مدل زمینساخت فلات آذربایجان (شمال گسل تبریز و جنوب ارس)، 21 تیر 1390، م. علوم زمین، شماره 87.
6
شهامت، ا.، 1381، بررسی نقش تنسور دوران بهعنوان یک معیار تغییر شکل در مطالعه پدیدههای ژئودینامیکی در ایران، پایاننامه کارشناسی ارشد ژئودزی، دانشکده نقشهبرداری، دانشگاه خواجهنصیرالدینطوسی.
7
فخرائی، ز.، پورکرمانی، م. و مؤید، م.، 1388، زمینشناسی ساختمانی، لرزهخیزی و لرزه زمینساخت سد خاکی ورزقان میانه، پاییز 1388، فصلنامه علمیپژوهشی زمین
8
و منابع واحد لاهیجان،سال اول، شماره اول.
9
موسوی، ز.، 1384، پهنهبندی و تعیین نرخ تغییرات ممان لرزهای در ایران بر پایه مشاهدات GPS، پایاننامه کارشناسی ارشد ژئودزی، دانشکده نقشهبرداری، دانشگاه خواجهنصیرالدینطوسی.
10
Altiner, Y., 1999, Analytical surface deformation theory for detection of the Earth’s crust movments, Springer-Verlag. Berlin Heidelberg.
11
Berberian, M., 1997, Seismic source of the
12
transcaucasian historical earthquakes. in: historical and prehistorical earthquakes in the caucasus (D. Giardini and S. Balassanian, eds.), NATO ASI Series, 2. Environment- Vol. 28, 233-311, Kluwer Academic Press, the Netherlands.
13
Coopley, A. and Jackson, J., 2006, Active tectonic of the Turkish – Iranian Plateau, TECTONICS, VOL. 25, TC6006, doi: 10.1029/2005TC001906.
14
Jamour, Y., Vernant, P., Nankali, H. and Tavakoli, F., 2011, NW Iran-eastern Turkey present-day kinematics: Results from the Iranian permanent GPS network, Earth and Planetary Science Letters, 370, 27-34.
15
Eringen, A. C., 1962, Nonlinear theory of continuous media: McGraw-Hill. New York.
16
Heitz, S., 1988, Coordinates in geodesy, Springer-Verlag, Berlin Heidelberg.
17
Karimzadeh, S., Cakir, Z., Osmanoglu, B., Schmalzle, G., Miyajima, M., Amiraslanzadeh, R. and Djamour, Y., 2013, Interseismic strain accumulation across the North Tabriz Fault (NW Iran) deduced from InSAR time series: Journal of Geodynamics, 66, 53-58.
18
Masson, F., Anvari, M., Djamour, Y., Walpersdorf, A., Tavakoli, F., Daignieres, M., Nankali, H. and Vav Grop, S., 2007, Larg-scale velocity field and strain tensor in Iran inferred from GPS measurements: new insight for the present-day deformation pattern within NE Iran, Geophys. J. Int., 170, 436-440.
19
Mousavi, Z., Walpersdorf, A., Walker R. T., Tavakoli, F., Pathier, E., Nankali, H., Nilfouroushan, F. and Djamour, Y., 2013, Global Positioning System constraints on the active tectonics of NE Iran and the South Caspian Region: Earth and Planetary Science Letters, 08/2013.
20
Nilfouroushan, F., Hodacs, P., Koyi, H. and Sjoberg, L., 2012, Geodetic horizontal velocity and strain rate fields around Lake Vanern (SW Sweden) derived from GPS measurements between 1997 and 2011: Proc. EGU General Assembly Conference, 04/2012.
21
Terada, T. and Miyabe, N., 1929, Deformation of earth crust in Kiranasai District and its relation to the orographic feature, Bulletin of Earthquake Research Institute, 7, 223-241, University of Tokyo.
22
Vanicek, P. and Krakiwsky, E., 1982, Geodesy: the concepts, North-Holand.
23
Voosoghi, B., 2000, Intrinsic deformation analysis of the Earth surface based on 3-dimensional displacement fields derived from space geodetic measurements, Ph.D. thesis, Institute of Geodesy, University at Stuttgart, Germany.
24
Zarifi, Z., Nilfouroushan, F. and Raeesi, M., 2013, Crustal stress map of Iran, insight from seismic and geodetic computations, Pure Appl. Geophys, 170, 1361-1672.
25
ORIGINAL_ARTICLE
Interpretation of Magnetic Data, based on Tilt Derivative Methods and Enhancement of Total Horizontal Gradient, A Case Study of Zanjan Depesion
Magnetic survey data are generally used to map faults, geologic contacts and magnetic ore bodies. The spatial distribution of magnetic sources will be determined during the mapping process. Variation in depth, magnetization and geometrical parameters generate magnetic anomaly waveform. Direction of the remanent and induced magnetization vector will also affect the shape of these waveforms. A magnetic anomaly waveform includes amplitude, phase and wavelength. Putting these parameters altogether makes the interpretation of the magnetic data a difficult task. There are different useful methods for interpretation of a magnetic map. Generally, these methods are based on reduction data to a simpler form, so that the edges and center of the causative bodies will be determined easily. In recent years many methods have been used to balance the difference between various anomaly amplitudes. Each method is designed to determine a specific parameter of the magnetic anomalies. Local phase filters are commonly used in potential field data interpretation. They are high-pass filters based on horizontal and vertical derivatives, such as total horizontal derivative, tilt angle, theta map, etc.Edge detection of a magnetic structure is one of the most important issues in the interpretation of magnetic data. In the present study we have used two local phase filters for this purpose: Tilt angle (TDR) and Total Gradient of Tilt angle (TAHG). Although the tilt angle filter is used to determine the boundary of anomaly sources, but it is relatively less sensitive to the source depth, so it can resolve shallow and deep sources as well. As the tilt angle is a function of vertical derivatives normalized by horizontal derivatives of magnetic field intensity (THDR), it does not contain information on the strength of the geomagnetic field nor the susceptibility of the causative bodies. The tilt angle amplitudes depend strongly on magnetic field inclination. Their maximum occurs at the center of the magnetic sources and they disappear over the anomaly edges.Another enhancing method employed in this study to determine the structure boundaries, is the tilt derivative of horizontal gradient. It is defined by taking the arctangent of the vertical derivative of the THDR, divided by the modulus of the horizontal gradient of THDR:TAHG=arctan〖((∂THDR/∂z)/√(〖(∂THDR/∂x)〗^2+〖(∂THDR/∂y)〗^2 ))〗TAHG equalizes the signals obtained from shallow and deep sources. This method has two notable features: I- it produces maximum amplitudes over the edges of the sources, II- it gives suitable resolution and is less dependent on the structure depths. However, like the TDR, this method depends on the inclination of magnetic field.We applied these methods for synthetic noise-free and noisy data. Magnetic responses of synthetic models as well as calculations of different edge detection methods have all been done in MATLAB. In comparison with common methods like horizontal gradient and analytic signal, it delineates the edges of sources more efficiently and accurately. Furthermore the TAHG method has better resolution in determining the boundaries of deeper sources than TDR method. We applied the TAHG method for the aeromagnetic dataset from Zanjan region. The Zanjan depression is a narrow and continuous igneous basin, located in the north western Zanjan province. There are many young active and basement faults in the study area. Total magnetic anomaly map of the region, shows two major structural trends in NW-SE and NE-SW, respectively. Applying different edge detection algorithms we obtained the hidden boundaries of the basement which is not detectable in the geological maps because of the thick sedimentary covers. The results show that TAHG method is suitable for determining the basement faults and boundaries, as well as mapping the contacts of magnetic units.
https://jesphys.ut.ac.ir/article_58910_36c0fef1acee4c1395a698df3c1e06c8.pdf
2017-04-21
101
113
10.22059/jesphys.2017.58910
Potential Field
Magnetic Anomaly
Tilt Angle of Horizontal Gradient
Vertical Gradient
Edge detection
محبوبه
شاهوردی
mahboobeh.shahverdi@gmail.com
1
کارشناس ارشد ژئوفیزیک
AUTHOR
لقمان
نمکی
loqmanamaki@gmail.com
2
عضو هیئت علمی دانشگاه آزاد سنندج
AUTHOR
منصوره
منتهایی
mmontaha@ut.ac.ir
3
هیئت علمی موسسه ژئوفیزیک
LEAD_AUTHOR
فاطمه
مصباحی
mesbahifatemeh@gmail.com
4
عضو هیئت علمی دانشگاه تبریز
AUTHOR
مهدی
بساوند
mehdibasavand@gmail.com
5
کارشناسی ارشد تکتونیک
AUTHOR
شاهوردی، م.، 1392، مقایسه روشهای مختلف برای تعیین موقعیت لبۀ ساختارهای بیهنجاری مغناطیسی، سمینار کارشناسی ارشد، مؤسسۀ ژئوفیزیک دانشگاه تهران.
1
مصباحی، ف.، 1386، تحلیل هندسی و جنبشی سیستم گسلهای نرمال در نهشتههای افقی. پایان نامۀ کارشناسی ارشد. دانشگاه تربیت مدرس.
2
دانشگاه تهران.
3
Blakely, R. J., 1996, Potential theory in gravity and magnetic applications, Cambridge University Press.
4
Blakely, R. J. and Simpson, R. W., 1986, Approximating edges of source bodies from magnetic or gravity anomalies, Geophysics, 51, 1494–1498.
5
Cooper, G. R. J. and Cowan, D. R., 2006, Enhancing potential field data using filters based on the local phase: Computers Geosciences, 32(10), 1585-1591, doi: 10.1016/j.cageo.2006.02.016.
6
Cooper, G. R. J. and Cowan, D. R., 2008, Edge enhancement of potential field data using normalized statistics, Geophysics, 73(3), H1-H4, doi: 10.1190/1.2837309.
7
De Barros, A., Bongiolo, S. and Ferreira, F. J. F., 2012, Evaluation of enhancement techniques of magnetic anomalies applied to structural interpretation of the Itauba Region, State of Para, Brazil, Revista Brasileira de Geof′ısica, 30(3).
8
De Castro, D. L., Fuck, R. A., Phillips, J. D., Vidotti, R. M., Bezerra, F. H. and Dantas, E. L., 2014, Crustal structure beneath the Paleozoic Parnaíba Basin revealed by airborne gravity and magnetic data, Brazil. Tectonophysics, 614, 128-145.
9
Ferreira, F. J., de Souza, J., de B. e S. Bongiolo, A. and de Castro, L. G., 2013, Enhancement of the total horizontal gradient of magnetic anomalies using the tilt angle, Geophysics, 78(3), J33-J41.
10
Hajian, J. and Zahedi, M., 2004, Geological map of Zanjan, 1:100000, Tehran, GSI.
11
Ma, G., 2013, Edge detection of potential field data using improved local phase filter, Exploration Geophysics, 44(1), 36-41.
12
Miller, H. G. and Singh, V., 1994, Potential field tilt -A new concept for location of potential field sources, Journal of Applied Geophysics, 32, 213-217.
13
Salem, A., Williams, S., Fairhead, J. D., Ravat, D. and Smith, R., 2007, Tilt-depth method, a simple depth estimation method using first-order magnetic derivatives, The Leading Edge 26(12), 1502-1505.
14
Solaymani Azad, S., Dominguez, S., Philip, H., Hessami, K., Forutan, M. R., Shahpasan Zadeh, M. and Ritz, J. F., 2011, The Zandjan fault system: morphological and tectonic evidences of a new active fault network in the NW of Iran, Tectonophysics, 506(1), 73-85.
15
Wijns, C., Perez, C. and Kowalczyk, P., 2005, Theta map: edge detection in magnetic data, Geophysics, 70(4), L39–L43, doi: 10.1190/1.1988184.
16
ORIGINAL_ARTICLE
Estimation of depth, location and structure index of magnetic anomalies by enhanced local wavenumber method
A reliable analysis of magnetic data is the correct estimation of the causative sources to plan for drilling to achieve the targets. This paper presents enhanced local wave number (ELW) method for interpretation of the magnetic data. ELW method has been proposed during the previous decades and is based on analytic signal to estimate the location and depth of the anomalies without having any knowledge about the geometry and magnetic susceptibility of the source. Final equation in this technique, is based on the depth and position and is independent of the structural index. The solution of normal this equation is obtained by assigning ELW kx and kz (the local wave number with respect to x and z) for different values of x and heights of continuation, z within a window centred with the peak of the analytic signal amplitude. A problem of over determined unknown parameters can be solved through a standard technique, using the least squares approach, therefore, the Golub algorithm is used to solve a set of linear equations. The ELW technique requires computation of horizontal and vertical derivatives of the first and second orders. Due to this characteristic, any high frequency noise present in the data gets substantially enhanced, masking the response from a target. To restrict the high frequency response, a window function is designed on the basis of the maximum frequency computed from Agrawal and Lal (1972). After finding these quantities the method can approximate the structure index. Although, an appropriate Matlab code for the method is introduced and tested on two dimensional synthetic data before and after adding noises. There is a peak in the curves of analytic signal and kx of ELW and also a turning point in the curve of kz of ELW witch shows the position of anomaly. Existence of these features shows that final responses of ELW method are correct. Synthetic data produced from a dyke like body with dip, magnetization, declination, inclination, depth and thickness are 45º, 1( ), 90º, 64º, 10m and 15m respectively. The ELW method has had reasonable responses for noises with different amplitudes up to 20nT and for noises with amplitude more than 20nT, ELW method looses its efficiency. Then, the method is tested by applying on the real data of Golbelaghi area in Zanjan, and ok compared with the results obtained from Model vision software. To do this a 525m profile is used. At the end, the depth and structure index are obtained about 4m and 0.8, respectively, using ELW method and the depth is estimated about 4.4m using model vision software. It is worthy to note that the depth of anomaly has been reported 4.5m by drilling. The parameters obtained from the introduced method for the anomalies show that the enhanced local wavenumber method and its introduced Matlab code can be a powerful tool in the studies of local anomalies. Because this method is automatic and quick, it can be used for large data sets like vast area or airborne data. This method is used on airborne data of Damghan region in another paper.
https://jesphys.ut.ac.ir/article_58909_83562631be3b5219af65dbac74349fd6.pdf
2017-04-21
115
131
10.22059/jesphys.2017.58909
Analytic signal
Enhanced Local Wavenumber
Golbelaghi region
Zanjan
Ramin
Ghasemiannia
ramin_ghasemian@alumni.ut.ac.ir
1
موسسه ژئوفیزیک دانشگاه تهران
AUTHOR
Behrooz
Oskooi
boskooi@ut.ac.ir
2
Institute of Geophysics, Associate Professor
LEAD_AUTHOR
Agarwal, B. N. P. and Lal, T., 1972a, A generalized method of computing second derivative of gravity field, Geophysical Prospecting, 20, 385-394.
1
Agarwal, B. N. P. and Lal, T., 1972b, Calculation of the vertical gradient of the gravity field using the Fourier transform, Geophysical Prospecting, 20, 448-458.
2
Ansari, A., H. and Alamdar, K., 2010, 3-D depth and susceptibility estimation of magnetic anomalies using Local Wavenumber (LW) method, Iranian Journal of Science & Technology, Transaction B: Engineering, 34(B5), 567-575.
3
Bulent, O., Ertan, P. and Serafeddin, C., 2010, Interpretation of magnetic anomaly in the south of lake Sapanca using an Enhanced Local Wave number method, Journal of Engineering Science and Design, 1(2), 87-90.
4
Golub, G., 1965, Numerical methods for solving linear least squares problems, Numerische Mathematik, 7, 206-216.
5
Keating, P. and Pilkington, M., 2004, Euler deconvolution of the analytic signal and its application to magnetic interpretation, Geophysical Prospecting, 52, 165-182.
6
Ku, C. C. and Sharp, J. A., 1983, Werner method for automated magnetic interpretation and its refinement using Marquardt inverse modeling, Geophysics, 48, 754-774.
7
Ma, G. Q., 2013, Improved local wavenumber methods in the interpretation of potential field data, Pure and Applied Geophysics, 170, 633-643.
8
MA, G. Q., DU, X. J. and LI, L. L., 2012, Interpretation of potential field tensor data using the tensor local wavenumber method and comparison with the conventional local wavenumber method, Chinese Journal of Geophysics, 55(4), 380-393.
9
Murthy, K. S. R. and Mishra, D. C., 1980, Fourier transform of the general expression for the magnetic anomaly due to a long horizontal cylinder, Geophysics, 45, 1091-1093.
10
Nabighian, M. N., 1972, The analytic signal of two-dimensional magnetic bodies with polygonal cross-section: its properties and use for automated anomaly interpretation, Geophysics, 37, 507-517.
11
Naudy, H., 1971, Automatic determination of depth on aeromagnetic profile, Geophysics, 36, 717-722.
12
Peters, L. J., 1949, The direct approach to magnetic interpretation and its practical application, Geophysics, 14, 290-320.
13
Reford, M. S., 1964, Magnetic anomalies over thin sheets, Geophysics, 29, 532-536.
14
Ridsdill-Smith, T. A. and Dentith, M. C., 1999, The wavelet transform in aeromagnetic processing, Geophysics, 64, 1003-1013.
15
Salem, A., Ravat, D., Smith, S. and Ushijima, K., 2005, Interpretation of magnetic data using an enhanced local wave number (ELW) method, Geophysics, 70, L7-L12.
16
Smith, R. S., Thurston, J. B., Dai, T. F. and Macleod, I. N., 1998, iSPI the improved source parameter imaging method, Geophysical Prospecting, 46, 141-151.
17
Thompson, D. T., 1982, EULDPH—a new technique for making computer assisted depth estimates from magnetic data, Geophysics, 47, 31-37.
18
Thurston, J. B. and Smith, R. S., 1997, Automatic conversion of magnetic data to depth, dip, and susceptibility contrast using the SPI method, Geophysics, 62, 807-813.
19
Thurston, J. B., Smith, R. S. and Guillon, J. C., 2002, A multimodel method for depth estimation from magnetic data, Geophysics, 67, 555-561.
20
ORIGINAL_ARTICLE
Investigation of the accuracy of the European Center for Medium Range Weather Forecast (ECMWF) in forecasting observed precipitation in different climates of Iran
The lack of reliable and updated precipitation datasets is the most important limiting factor in studying many climatological and hydrological topics including climate change and temporal variability of precipitation in many data sparse areas around the globe. This is particularly valid for Iran that encompasses vast deserts and un-settled hyper-arid climate areas (central-eastern Iran) that hinders establishing an adequate network of rain-gauge stations required for climatological studies. Similarly, the high elevation areas of mountainous regions of western and northern Iran suffer from limited representative stations. Using the gridded or reanalysis precipitation datasets could be one of the possible solutions to overcome this obstacle; knowing that the representativeness of these datasets has been already proved for many different parts of the world. Amongst many available gridded precipitation datasets are the Global Precipitation Climatology Center (GPCC) and the Tropical Rainfall Measuring Mission (TRMM) that have been widely used in many researches; indicating their accurate estimation of precipitation values and intra-annual variation for the regions studied. The reanalysis precipitation dataset which is a product of the Numerical Weather Prediction (NWP) models is an alternative source of precipitation data that is widely used in the literature and many authors have pointed to the relatively accurate precipitation prediction of reanalysis for many parts of the word. The two widely used reanalysis datasets are NCEP/NCAR and different products of ECMWF, namely ERA-15, ERA-40 and ERA-Interim reanalysis. ERA-Interim which is used in the present study is produced at T255 spectral resolution (about 80 km) and covers the period from January 1979 to present, with product updates at approximately 1 month delay from real-time (Dee et al., 2011; Balsamo et al., 2015). The ERA-Interim atmospheric reanalysis is built upon a consistent assimilation of an extensive set of observations (typically tens of millions daily) distributed worldwide (from satellite remote sensing, in situ, radio sounding, profilers, etc.). To develop the reanalysis, the analysis step combines the observations with a prior estimate of the atmospheric state (first-guess fields) produced with a global forecast model in a statistically optimal manner (Balsamo et al., 2015).The representativeness and performance of ERA-Interim in forecasting precipitation amount at 45 Iranian synoptic stations distributed across the country is herein examined. Spatial resolution of ERA-Interim dataset used in this study is 0.125 × 0.125 in latitude and longitude. For each station, the closest grid point of ERA-Interim to the station coordinates was chosen for a statistical comparison analysis. To evaluate the performance of the considered dataset when compared to the observed precipitation records at the considered locations we have used R squared, the Nash–Sutcliffe model efficiency coefficient (EF), RMSE, Bias, B slope of the regression and the standardized RMSE indicators. The performance of the dataset was also graphically represented through scatter plots of the established regression between ERA-Interim and observation at the selected stations. The results of the statistical indicators were represented through plotting the indicators over the map of Iran to ease displaying spatial tendency of the indicators and explaining the possible geographical role in controlling the spatial variation of the indicators. The results indicate that the ERA-Interim performs well in majority of the studied stations with strong correlation coefficient. However, it was found that the ERA-Interim underestimates precipitation in most of the stations located in the coastal areas of the Caspian Sea as well as in some stations along the Persian Gulf and the Oman Sea, suggesting that ERA-Interim is somewhat inefficient in adequately forecasting precipitation in the coastal areas; very likely due to not properly taking into account the complex topography of the region in its model parameterization or not being able to adequately differentiate between land and sea characteristics for the stations very close to the sea. It should be noted that the ERA-Interim is less efficient in accurately forecasting extreme precipitation in the Caspian Sea region. Nevertheless, we found very high agreement between observations and ERA-Interim in this region when some extreme precipitation events were excluded from the analysis. Contrarily, the results suggest an over-estimation for most of the stations located in northwestern and northeastern mountainous areas of the country; once again due to perhaps improper representation of topography of these regions in the model.
https://jesphys.ut.ac.ir/article_57958_7ac45d1266a9ec55b595cc05e33aa3be.pdf
2017-04-21
133
147
10.22059/jesphys.2017.57958
"Precipitation"
"ECMWF"
" ERA-Interim"
"statistical indicators"
"Iran"
Tayeb
Raziei
tayebrazi@yahoo.com
1
پژوهشکده حفاظت خاک و آبخیزداری
LEAD_AUTHOR
Fatemeh
Sotoudeh
fsotoudeh@ymail.com
2
Student
AUTHOR
تقوی، ف.، نیستانی، ا. و قادر، س.، 1392، ارزیابی پیشبینیهای کوتاهمدت بارش مدل عددی WRFدر منطقة ایران در دورة یک ماهه، م. فیزیک زمین و فضا، 39(2)، 170-145.
1
دارند، م. و زندکریمی، س.، 1394، واکاوی سنجش دقت زمانی-مکانی بارش پایگاه داده مرکز پیشبینی
2
میانمدت جوّی اروپایی (ECMWF) روی ایران زمین، م. پژوهشهای جغرافیای طبیعی، 47(4)، 651-675.
3
رضیئی، ط. و فتاحی، ا.،1390، ارزیابی کاربرد دادههای NCEP/NCAR در پایش خشکسالی ایران، م. فیزیک زمین و فضا، 37(2)، 247-225.
4
هدایتی دزفولی، ا. و آزادی، م.، 1389، راستیآزمایی پیشبینی بارش مدل منطقهای MM5روی ایران، م. فیزیک زمین و فضا، 36(3)، 129-115.
5
Balsamo, G., Albergel, C., Beljaars, A., Boussetta, S., Brun, E., Cloke, H., Dee, D., Dutra, E., Muñoz-Sabater, J., Pappenberger, F., de Rosnay, P., Stockdale, T. and Vitart, F., 2015, ERA-Interim/Land: a global land surface reanalysis data set, Hydrol. Earth Syst. Sci., 19, 389-407.
6
Belo-Pereira, M., Dutra, E. and Viterbo, P., 2011, Evaluation of global precipitation data sets over the Iberian Peninsula, Journal of Geophysical Research, Atmospheres, 116, D20101.
7
Bengtsson, L. and Shukla, J., 1988, Integration of space and in situ observations to study global climate change, Bull. Am. Meteorol. Soc., 69, 1130-1143.
8
Dee, D., Uppala, S., Simmons, A., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, ACM., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., H´olm, E. V., Isaksen, L., Kallberg, P., Kohler, M., Matricardi, M., McNally, A. P., Monge-Sanz, B. M., Morcrette, J. J., Park, B. K., Peubey, C., de Rosnay, P., Tavolato, C., Th´epaut, J. N. and Vitart, F., 2011, The ERA-Interim reanalysis, configuration and performance of the data assimilation system, Q. J. R. Meteorol. Soc., 137, 553-597.
9
deLeeuw, J., Methven, J. and Blackburn, M., 2014, Evaluation of ERA-Interim reanalysis precipitation products using England and Wales observations, Q. J. R. Meteorol. Soc., 141, 798-806.
10
Diro, G. T., Grimes, D. I. F., Black, E., O'Neill, A. and Pardo-Iguzquiza, E., 2009, Evaluation of reanalysis rainfall estimates over Ethiopia, Int. J. Climatol., 29(1), 67-78.
11
Kanamitsu, M., Ebisuzaki, W., Woollen, J., Yang, S.-K., Hnilo, J. J., Fiorino, M. and Potter, G. L., 2002, NCEP-DOE AMIP-II reanalysis (R-2), Bull. Am. Meteorol. Soc., 83, 1631-1643.
12
Ma, L., Zhang, T., Frauenfeld. W., Oliver, Ye., Yang, D. and Qin, D., 2009, Evaluation of precipitation from the ERA-40, NCEP-1, and NCEP-2 Reanalyses and CMAP-1, CMAP-2, and GPCP-2 with ground-based measurements in China, J Geo Rese, 114, doi:10.1029/2008JD011178, 2009.
13
Moriasi, D. N., Arnold, M. W., Van Liew, R. L., Harmel, R. D. and T. L. Veith., 2007, Model evaluation guidelines for systematic quantification of accuracy in watershed simulations, Transactions of the ASABE, 50(3), 885-900.
14
Pena-Arancibia, J. L., Van dijk, A. I. J. M., Renzullo, L. J. and Mulligan, M., 2013, Evaluation of Precipitation Estimation Accuracy in Re-analyses, Satellite Products, and an Ensemble Method for Regions in Australia and South and East Asia, Jour Hydromet, 14, 1323-1333.
15
Raziei, T. and Pereira. S. L., 2013, Spatial variability analysis of reference evapotranspiration in Iranutilizing fine resolution gridded datasets, Agri Water Manage, 126, 104-118.
16
Raziei, T., Bordi, I. and Pereira, L. S., 2011, An application of GPCC and NCEP/NCAR datasets for drought variability analysis in Iran, Water Resour Manage, 25, 1075-1086.
17
Raziei, T., Bordi. I., Pereira, L. S. and Sutera, A., 2010, Space-time variability of hydrological drought and wetness in Iran using NCEP/NCAR and GPCC datasets, Hydrol Earth Syst. Sci., 14, 1919-1930.
18
Raziei, T., Saghafian, B., Paulo, A. A., Pereira, L. S. and Bordi, I., 2009, Spatial and temporal variability of drought in western Iran, Water Resour. Manage, 23, 439-455.
19
Rhodes, R. I., Shaffrey, L. C. and Gray, S. L., 2015, Can reanalyses represent extreme precipitation over England and Wales?, Q. J. R. Meteorol. Soc, 141, 1114-1120.
20
Rubel, F. and Rudolf, B., 2001, Global daily precipitation estimates proved over the European Alps, Meteorol Z, 10(5), 407-418.
21
Schiemann, R., luthi, D., Luigi, V. P. and Schar, h., 2008, The precipitation climate of Central Asia – intercomparison of observational and numerical data sources in a remotesemiarid region, Int. J. Climatol, 28, 295-314.
22
Sodoudi, S., Noorian, A. M., Manfred, G. and Eberhard, R., 2010, Daily precipitation forecast of ECMWF verified over Iran, TheorApplClimatol, 99, 39-51.
23
Trenberth, K. E. and Olson, J. G., 1988, An evaluation and intercomparison of global analyses from NMC and ECMWF, Bull. Am. Meteorol. Soc., 69, 1047-1057.
24
Uppala, S. M., Kallberg, P. W., Simmons, A. J., Andrae, U., Da Costa Bechtold, V., Fiorino, M., Gibson, J. K., Haseler, J., Hernandez, A., Kelly, G. A., Li, X., Onogi, K., Saarinen, S., Sokka, N., Allan, R. P., Andersson, E., Arpe, K., Balmaseda, M. A., Beljaars, A. C. M., Van De Berg, L., Bidlot, J., Bormann, N., Caires, S., Chevallier, F., Dethof, A., Dragosavac, M., Fisher, M., Fuentes, M., Hagemann, S., H´olm, E., Hoskins, B. J., Isaksen, L., Janssen, P., Jenne, R., McNally, A. P., Mahfouf J. F., Morcrette, J. J., Rayner, N. A., Saunders, R. W., Simon, P., Sterl, A., Trenberth, K. E., Untch, A., Vasiljevic, D., Viterbo, P. and Woollen, J., 2005, The ERA-40 re-analysis, Q. J. R. Meteorol. Soc., 131, 2961-3012.
25
Wang, A. and Zeng, X., 2012, Evaluation of multireanalysis products with in situ observations over the Tibetan Plateau, Jour Geo Resea,117, D05102, doi: 10.1029/2011JD016553.
26
Zhao, T. and Fu, C., 2006, Comparison of products from ERA-40, NCEP-2, and CRU with station data for summer precipitation over China, Advances in Atmospheric sciences, 23, 593-604.
27
ORIGINAL_ARTICLE
Study of the climate anomaly of Iran in Aban 1390 (23rd Oct. to 21st Nov. 2011) from the perspective of the large-scale dynamics
Based on the report by Islamic Republic of Iran Meteorological Organization (IRIMO) published as part of a greater report on the state of the world climate in 2011 by the American Meteorological Society (Blunden and Arndt, 2012), large parts of Iran, from central to northern and northeastern areas, have experienced significant negative anomalies of surface temperature together with positive anomalies of precipitation in autumn 2011. The temperature and precipitation anomalies have been determined with respect to the climatological mean values over the period 1960 to 2010. As the establishment of a prolonged period of cold weather in Aban 1390 (23rd Oct. to 21st of Nov. 2011) together with abundant precipitation in the form of both rain and snow played a great role in shaping the climate anomalies of autumn 2011 in Iran, this study aims to investigate the large-scale dynamical processes involved in the climate anomalies of this period. Such studies are particularly important, when the increase in the frequency of extreme climate anomalies in recent years and its possible link with global warming is noted. To this end, the NCEP/NCAR reanalysis data are used for the concerned period and the long-term mean fields (from 1950 to 2010). The main analysis tools used are the analysis of the anomalies of geopotential height and temperature in the lower and middle troposphere, jet speed and relative vorticity in the upper troposphere, the computation of the blocking index (BI) introduced by Wiedenmann et al. in 2002, and the energy diagnostics. The latter includes the eddy kinetic energy, ageostrophic geopotential flux and its convergence, total flux and its convergence, baroclinic generation, baroclinic conversion, and barotropic conversion. The results for the year 2011 indicate the action of two consecutive blocking systems, which extended their central ridges over Europe with their troughs stretched over the North Atlantic and the west of Asia. The two blocking systems were peaked in the 3rd and 21st of Aban 1390, with respectively moderate and high intensities as measured by BI. In addition, the obtained results show that a branch of Siberian high-pressure system extended to the west of Asia associated with a positive relative vorticity anomaly in the north of Iran, lead to vigorous cold air advection to the North and Northwest of Iran. The increase in eddy kinetic energy over a band stretched from the North Atlantic to the Mediterranean and Black Seas in Aban 1390 was associated with an increase in the strength as well as the zonal and meridional extensions of the subtropical jet. Concerning energy diagnostics, the positive anomalies of the ageostrophic and total flux convergence over Iran indicate that the country was a favorable region for receiving large amounts of energy. Also, the flux vectors demonstrate that the main passage of this energy to Iran was through a north–south extent that included an emission area over the Black Sea. This was further confirmed by the analysis of baroclinic generation, which showed a positive anomaly over the Black Sea. The analysis also shows that the low-frequency phenomena and teleconnection patterns, including the positive phases of the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), and the positive phase of the East Atlantic–West Russia (EA–WR) may have played a part in shaping the climate anomaly over Iran in Aban 1390.
https://jesphys.ut.ac.ir/article_58906_aa7cb29397bbadc51f49299bbd435b9a.pdf
2017-04-21
149
164
10.22059/jesphys.2017.58906
Large-scale dynamics
anomaly
Blocking
baroclinic generation
ageostrophic flux
total flux
علیرضا
محب الحجه
amoheb@ut.ac.ir
1
هیئت علمی موسسه ژئوفیزیک
LEAD_AUTHOR
زکیه
علی زاده
zaki_alizadeh@alumni.ut.ac.ir
2
موسسه ژئوفیزیک دانشگاه تهران
AUTHOR
فرهنگ
احمدی گیوی
ahmadig@ut.ac.ir
3
موسسه ژئوفیزیک دانشگاه تهران
AUTHOR
اسبقی، ق.، 1393، بررسی اثرات برونحارهای نوسان شبهدوسالانه بر پوشنسپهر میانی و زیرین. پایاننامۀ کارشناسی ارشد هواشناسی، مؤسسه ژئوفیزیک دانشگاه تهران.
1
حسینپور، ف.، 1388، بررسی بیهنجاری آبوهوایی زمستان 1386 از دیدگاه دینامیک بزرگمقیاس. پایاننامۀ کارشناسی ارشد هواشناسی، مؤسسه ژئوفیزیک دانشگاه تهران.
2
حسینپور، ف.، محبالحجه، ع. ر. و احمدی گیوی، ف.، 1391، دینامیک مسیرهای توفان در زمستان 2007–2008 از دیدگاه انرژی، م. فیزیک زمین و فضا، 38(4)، 175–187.
3
فهیمی، س.، احمدی گیوی، ف. و مزرعهفراهانی، م.، 1392، بررسی اقلیمشناختی بندالهای آسیا و اروپا با دو شاخص در دورۀ 1950–2010، م. ژئوفیزیک ایران، 7(4)، 31–51.
4
عباسزاده اقدم، ک.، محبالحجه، ع. ر. و احمدی گیوی، ف.، 1393، بررسی اثرهای اقلیمشناختی تاوه قطبی پوشنسپهر در منطقۀ جنوبغرب آسیا، م. فیزیک زمین و فضا، 40(4)، 127–138.
5
علیزاده، ز.، 1392، بررسی بیهنجاری دما و بارش ایران در پاییز 1390 از دیدگاه دینامیک بزرگمقیاس. پایاننامۀ کارشناسی ارشد هواشناسی، مؤسسۀ ژئوفیزیک دانشگاه تهران.
6
محمدآبادیکمرئی، آ.، 1390، بررسی بیهنجاری آبوهوایی زمستان 1388 از دیدگاه دینامیک بزرگمقیاس و مقایسه با زمستان 1386، پایاننامۀ کارشناسی ارشد هواشناسی، مؤسسۀ ژئوفیزیک دانشگاه تهران.
7
مقصودی فلاح، م.، 1392، اثر الگوی دورپیوند شرق – اطلس غرب آسیا (EA–WR) بر وردایی کمبسامد در منطقۀ جنوبغرب آسیا، پایاننامۀ کارشناسی ارشد هواشناسی، مؤسسۀ ژئوفیزیک دانشگاه تهران.
8
میررکنی، م.، محبالحجه، ع. ر. و احمدی گیوی، ف.، 1392، نقش گردشهای پوشنسپهر در بیهنجاریهای اقلیمی زمستانهای 1386 و 1388، م. ژئوفیزیک ایران، 7(1)، 104-89.
9
Barnston, A. G. and Livezey, R. E., 1987, Classification, seasonality and persistence of low-frequency atmospheric circulation patterns. Mon. Wea. Rev., 115, 1083-1126.
10
Blunden, J. and Arndt, D. S., 2012, State of the climate in 2011, Special Supplement to Bull. Amer. Meteor. Soc., 93, 224 pp.
11
Chang, E. K. M., 2001, The structure of baroclinic wave packets, J. Atmos. Sci., 58, 1694-1713.
12
Chang, E. K. M., Lee, S. and Swanson, K. L., 2002, Storm track dynamics, J. climate, 15, 2163-2183.
13
Croci-Maspoli, M., Schwierz C. and Davies, H. C., 2007, Atmospheric blocking: Space-time links to the NAO and PNA, Climate Dyn., 29, 713-725.
14
Holton, J. R., 2004, An introduction to dynamic meteorology, Elsevier Academic Press, 535pp.
15
Jeong, J. H., Ou, T., Linderholm, H. W. and Kim, B. M., 2011, Recent recovery of the Siberian high intensity, J. Geophys. Res., 116, D23102, doi: 10.1029/2011JD015904.
16
Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Leetmaa,
17
A., Reynolds, B., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Jenne, R. and Joseph, D., 1996, The NCEP/NCAR 40-year reanalysis project’. Bull. Amer. Meteor. Soc., 77, 437-472.
18
Kidston, J., Scaife, A. A., Hardiman, S. C., Mitchell, D. M., Butchart, N., Baldwin, M. P. and Gray, L. J., 2015, Stratospheric influence on tropospheric jet streams, storm tracks and surface weather. Nature Geoscience, 8, 433–440.
19
Latysheva, I. V., Belousova, E. P., Ivanova, A. S. and Potemkin, V. L., 2007, Circulation conditions of the abnormally cold winter of 2005/06 over Siberia. Russian Meteorology and Hydrology, 32, 572-575.
20
Nasr-Esfahany, M. A., Ahmadi-Givi, F. and Mohebalhojeh, A. R., 2011, An energetic view of the relation between the Mediterranean storm track and the North Atlantic Oscillation. Quart. J. R. Meteorol. Soc., 137, 749-756.
21
Thompson, D. W. J. and Wallace, J. M., 1998, The Arctic Oscillation signature in the wintertime geopotential height and temperature fields, Geophys. Res. Let., 25, 1297-1300.
22
Wen, M., Yang, S., Kumar, A. and Zhang, P., 2009, An analysis of the large-scale climate anomalies associated with the snowstorms affecting China in January 2008, Bull. Amer. Meteor. Soc., 137, 1111-1131.
23
Wiedenmann, J. M., Lupo, A. R., Mokhov, I. I. and Tikhonova, E. A., 2002, The climatology of blocking anticyclones for the Northern and Southern Hemispheres: Block intensity as a diagnostic, J. Climate, 15(23), 3459-3473.
24
Zhang, X., Lu, Ch. and Guan, Z., 2012, Weakened cyclones, intensified anticyclones and recent extreme cold weather events in Eurasia. Environ. Res. Lett., 7(4), 1-7.
25
Ziyin, Z., Daoyi, G., Miao, H., Dong, G., Xuezhao, H. and Yangna, L., 2009, Anomalous winter temperature and precipitation events in Southern China, J. Geogr. Sci., 19, 471-488
26
http://www.cpc.ncep.noaa.gov/data/indices/
27
ORIGINAL_ARTICLE
Extracting tidal frequencies of the Persian Gulf and Oman Sea using multivariate least square harmonic estimation of sea level coastal height observations time series
Tidal observations have been widely used for a variety of applications. Realistic functional and stochastic models of tidal observation are then required. The functional model is complete if one knows the tide characteristics such as tidal frequencies (M2 and S2 for instance). The stochastic model is complete if we know noise characteristics of tidal observations. There is always a prediction error between the predicted values and the observed tide heights. This can be investigated when taking the noise characteristics of tidal time series observations. Functional model identification is however the subject of discussion in the present contribution. Tide data are frequently used for different applications such as safe navigation. Real tide gauge data can be expressed by their tidal constituents (frequencies) and a noise structure. Using tidal frequencies and tidal observations one can employ the functional model to predict tide. Therefore identifying tidal frequencies is an important issue for tidal analysis. So far, most of the available methods to determine tidal frequencies have been based on the theory, and sea level height observations have not seriously been used to extract tidal frequencies. The theory-based methods usually apply the ephemeris of Moon, Sun and other planets to extract tidal frequencies without the use of tidal observations. Following-up the study by Amiri-Simkooei et al. (2014), we further focus on extracting tidal frequencies using tidal observations. For this purpose, we apply the least squares harmonic estimation (LS-HE) to the multivariate tidal time series. As a generalization of the Fourier spectral analysis, LS-HE is neither limited to evenly spaced data nor to integer frequencies. We may also note that the main tidal constituents may change from one area to another area. In this contribution, we use the data sets of eight coastal tide gauge stations in Persian Gulf and Oman Sea between 1999 and 2010 with a sampling rate of 30 min using a multivariate analysis. In multivariate analysis, the frequencies contributed in tide structure are more obvious than in the univariate analysis. Such signals can thus simply be detected in the multivariate analysis. Using the above-mentioned data, 414 main tidal constituents have been extracted. Our extracted lists of frequencies (of the Persian Gulf and Oman Sea) are compared with the two lists of frequencies consisting of 50 and 121 frequencies by the study of Amiri-Simkooei et al. (2014), which was applied to UK tide gauge stations. In the present contribution, new frequencies that belong to the tide gauge stations of the Persian Gulf and Oman Sea have been identified. Finally, a six-month prediction is performed for all stations using the two lists of main frequencies obtained in the two studies. The prediction results of the two studies are then compared using the estimated root mean squared error (RMSE). The RMSE difference of our predicted data show a reduction ranging from 2 cm to 7 cm compared to that predicted using the frequency lists of Amiri-Simkooei et al. (2014). The estimated RMSE of tide prediction using the frequencies obtained in this study ranges from 9 to 16 cm.
https://jesphys.ut.ac.ir/article_60304_2d9e8b555eb08b8a4026fb3335f512d0.pdf
2017-04-21
165
180
10.22059/jesphys.2017.60304
"Least square harmonic estimation (LS-HE) "
"Tidal frequencies"
"multivariate tidal time series analysis"
"coastal tide gauge"
"tide prediction"
"Persian Gulf and Oman sea
alireza
amiri-Simkooei
ar.amirisimkooei@gmail.com
1
دانشگاه اصفهان- هیئت علمی
LEAD_AUTHOR
kamal
parvazi
kamal.parvazi@ut.ac.it
2
Student
AUTHOR
جمال
عسگری
asgari@eng.ui.ac.ir
3
هیئت علمی- دانشگاه اصفهان
AUTHOR
Amiri-Simkooei, A. R., 2007, Least-squares variance component estimation: theory and GPS applications. Ph.D. thesis, Mathematical Geodesy and Positioning, Faculty of Aerospace Engineering, Delft University of Technology , Delft, Netherlands.
1
Amiri-Simkooei, A. R. and Asgari, J., 2012, Harmonic analysis of total electron contents
2
time series: methodology and results, GPS Solut, 16(1):77-88
3
Amiri-Simkooei, A. R., Tiberius, CCJM. and Teunissen, PJG., 2007, Assessment of noise in GPS coordinate time series: methodology and results, J Geophys Res 112, B07413. doi: 10.1029/2006JB004913
4
Amiri-Simkooei, A. R., Zaminpardaz, S. and Sharifi, M. A., 2014, Extracting tidal frequ-encies using multivariate harmonic analysis of sea level height time series, J Geod (2014) 88, 975-988, doi: 10.1007/s00190-014-0737-5
5
Baarda, W., 1968, A testing procedure for use in geodetic networks, Publ 2(5), Netherlands Geodetic Commission, Delf.
6
Büllesfeld, F. J., 1985, Ein Beitrag zur harmon-ischen Darstellung des gezeitenerzeugenden Potentials, Reihe C, Heft 314, Deut-sche Geodätische Kommission, München.
7
Capuano, P., De Lauro, E., De Martino, S. and Falanga, M., 2011, Waterlevel oscillations in the Adriatic Sea as coherent selfoscillations inferred by independent component analysis, Progr Oceanogr, 91, 447-460.
8
Cartwright, D. E. and Tayler, R. J., 1971, New computation of the tide generating potential, Geophys, J. R. Astron. Soc., 23, 45-74.
9
Ducarme, B., Venedilkov, A. P., de Mesquita, A. R., Costa, D. S., Blitzkow, D., Vieira, R. and Freitas, SRC., 2006, New analysis of a 50 years tide guage record at Cananéia (SP-Brazil) with the VAV tidal analysis program, Dynamic Planet, Cairns, Australia, 22–26 August, 2005. Springer, IAG Symposia, 130, 453-460.
10
Flinchem, E. P. and Jay, D. A., 2000, An introd-uction to wavelet transform tidal analysis met-hods, Estuar. Coast. Shelf Sci., 51, 177-200.
11
Jay, D. A. and Kukulka, J., 2003, Revising the paradigm of tidal analysis the uses of nonstationary, Ocean Dyn., 53, 110-125.
12
Sakamoto, Y., Ishiguro, M. and Kitagawa, G., 1986, Akaike information criterion statistics, D, Reidel Publishing Company, Tokyo 290 pp.
13
Mousavian, R. and Mashhadi-Hossainali, M., 2012, Detection of main tidal frequencies using least squares harmonic estimation meth-od, J. Geod. Sci., 2(3), 224-233.
14
Parvazi, K, Asgari, J, Amirisimkooei, A. R. and Tajfirooz, B., 2015, Determination of diffe-rence between datum and reference ellipsoid by using of analysis of altimetry data of Topex/Poseidon, Jason-1 and observations of coastal tide gauges, Volume 5, Number 1.
15
Pytharouli, S. and Stiros, S., 2012, Analysis of short and discontinuous tidal data: a case study from the Aegean Sea, Surv Rev., doi: 10.1179/ 1752270611Y.0000000035
16
Sakamoto, Y., Ishiguro M. and Kitagawa, G., 1986, Akaike information criterion statistics, D. Reidel Publishing Company, Tokyo 290 pp.
17
Sharifi, M. A. and Sam Khaniani, A., 2013, Least-squares harmonic estimation of the tropopause parameters using GPS radio occultation measurements, Meteorol Atmos. Phys., 120(1-2), 73-82.
18
Teunissen, PJG, 2000, Testing theory: an introduction, Delft University Press, Website: http://www.vssd.nl. Series on Mathematical Geodesy and Positioning
19
Teunissen, PJG. and Simons D. G., Tiberius CCJM, 2005, Probability and observation theory, Faculty of Aerospace Engineering, Delft University, Delft University of Technology, (lecture notes AE2-E01).
20
Venedikov, AP., Arnoso, J., Vieira, R., 2003, VAV: a program for tidal data processing, Comput Geosci 29:487502
21
Venedikov, A. P., Arnoso, J. and Vieira, R., 2005, New version of the program VAV for tidal data processing, Comput. Geosci, 31, 667-669.
22
ORIGINAL_ARTICLE
A laboratory study of the effect of internal waves on acoustic propagation
For calculating the acoustic pressure due to sound propagation at sea using usual methods (pressure variations signals), knowing the density distribution and consequently, changes the speed of sound in the environment is very important. Many environmental factors affect the distribution of the density at sea, depending on environmental conditions and geographical location and the weaknesses of each of them are different. One of them is internal waves which usually cause temporal and spatial changes and consequently affect the acoustic wave propagation in the ocean. Internal waves can be generated by tidal currents over sea floor sloping that is very common in the stratified oceans. Results of study in the some researches showed that internal waves can effected on sound waves in two ways: 1-Internal waves can be decrease sound level up to 25 dB due to sound mode coupling in an exact frequency. 2- Internal waves can fuscous and defocus sound waves because of sound speed fluctuation.The purpose of this study is a laboratory investigation of internal waves caused by fluctuation of a cylinder in a stratified glass channel with 3 meters long, 0.5 meter width and 1 meter height, on the sound waves propagation. In this study, using the double bucket and filling box method for generating stratification that stratification can be measured by one pair of salinity and temperature meters fixed on a rail moved up and down. Using the usual methods of setting up internal waves and using acoustical transducers in 53 KHz frequency, internal wave's effects on the propagation of sound waves, were investigated. In this study with usual optical method (Synthetic Schlieren) internal waves generated in the tank can be detected. In this method Internal wave generated in the glass tank change optical index of water layers and cased deviation of Straight lines designed on the back of tank. Laboratory results showed that sound waves can be focused and defocused due to the normal modes of internal waves. Some 9 experiments were done mainly in cases withvertical linear density stratified fluid. As the modal structure of internal waves in the water tank change due to the waves, constant density surfaces change slopes, hence changing the sound ray's paths and the amount of signals reaching the receivers. Similar results of numerical simulation also show similar behavior in the strength of the acoustic signal. Numerical simulation modeled by AcTUP v2.2L software that use KERAKENC method based on normal mode method. The acoustic signal can be weakened up to 54 per cent depending on the degree of sound ray divergence. We can conclusion that in the laboratory tank in this study internal waves effects on sound waves by focusing and defocusing and not by mode coupling. Similar behaviors can be expected in the open ocean as the existence of internal waves is ubiquitous. For this goal dimensionless numbers should be use. Bowen (1993) showed that for simulating a sound waves interaction with a phenomenon in laboratory scale we can use ka = k'a'. With this formula we can compare laboratory results with real results on oceans.
https://jesphys.ut.ac.ir/article_60299_184c7c53ab8801701e199f9ef547f543.pdf
2017-04-21
181
192
10.22059/jesphys.2017.60299
Internal waves
propagation of sound waves
focusing and defocusing of sound waves
Hamed
Deldar
h.deldar@inio.ac.ir
1
دانشجوی پژوهشگاه ملی اقیانوس شناسی و علوم جوی
AUTHOR
عباسعلی
علی اکبری بیدختی
bidokhti@ut.ac.ir
2
مدیر گروه موسسه ژئو فیزیک دانشگاه تهران
LEAD_AUTHOR
وحید
چگینی
v_chegini@inio.ac.ir
3
هیات علمی پژوهشگاه ملی اقیانوس شناسی و علوم جوی
AUTHOR
محمد
اکبری نسب
m.akbarinasab@umz.ac.ir
4
مدیر گروه فیزیک دریا دانشگاه بابلسر
AUTHOR
Aguilar, D., Sutherland, B.R. and Muraki, D.J., 2006, Laboratory generation of internal waves from sinusoidal topography, Deep Sea Research Part II: Topical Studies in Oceanography, 53(1), 96-115.
1
Baines, W. D. and Turner, J. S., 1969, Turbulent buoyant convention from a source in a confined region, J. Fliud Mech., 37, 51-80.
2
Bowen, S. G., 1993. Forward scattering of a pulsed continuous wave signal through laminar and turbulent thermal plumes.MASSACHUSETTS INST OF TECH CAMBRIDGE.
3
Dalziel, S.B., Hughes, G.O. and Sutherland, B.R., 2000, Whole-field density measurements by ‘synthetic schlieren’, Experiments in Fluids, 28(4), 322-335.
4
Dohan, K. and Sutherland, B., 2005, Numerical and laboratory generation of internal waves from turbulence, Dynamics of atmospheres and oceans, 40(1), 43-56.
5
Gostiaux, L. and Dauxois,T., 2007, Laboratory experiments on the generation of internal tidal beams over steep slopes, Physics of Fluids (1994-present),19(2), 028102.
6
Griffiths, R. W. and Bidokhti,A. A., 2008, Interleaving intrusions produced by internal waves: a laboratory experiment, Journal of Fluid Mechanics, 602, 219-239.
7
Katsnel’son, B. and Pereselkov,S.,2004, Space-frequency dependence of the Horizontal structure of a sound field in the presence of intense internal waves, Acoustical Physics,50(2), 169-176.
8
Katsnel’son, B. and Pereselkov, S., 2000, Low-frequency horizontal acoustic refraction caused by internal wave solitons in a shallow sea, Acoustical Physics, 46(6), 684.
9
Katsnel’son, B. G.,Pereselkov, S.A., Petnikov, V.G., Sabinin, K.D., and Serebryanyi, A.N., 2001, Acoustic effects caused by high-intensity internal waves in a shelf zone, Acoustical Physics,47(4), 424-429.
10
Lynch, J. F., Lin, Y.T., Duda, T. F. and Newhall, A. E., 2010, Acoustic ducting, reflection, refraction, and dispersion by curved nonlinear internal waves in shallow water, Oceanic Engineering, IEEE Journal of , 35(1), 12-27.
11
Mathur, M. and Peacock,T., 2009, Internal wave beam propagation in non-uniform stratifications, Journal of Fluid Mechanics, 639, 133-152.
12
Morgunov, Y. N., Polovinka, Y. A. and Strobykin, D.S., 2008, an experimental study of the effect of tide on acoustic field formed along a stationary track in the shelf zone of the Sea of Japan, Acoustical Physics, 54(4), 506-507.
13
Munk, W.,Zetler, B., Clark, J., Glll, S., Porter, D., Spiesberger, J. and Spindel, R., 1981, Tidal effects on long‐range sound transmission, Journal of Geophysical Research: Oceans (1978–2012), 86(C7), 6399-6410.
14
Preisig, J. C. and Duda,T. F.,1997, Coupled acoustic mode propagation through continental-shelf internal solitary waves, Oceanic Engineering, IEEE Journal of ,22(2), 256-269.
15
Pond, S. and Pickards, G. L., 1983, Introductory Dynamical Oceanography, Butterworth and Heineman Ltd., 328 pp.
16
Reeder, D. B., Duda, T.F. and Ma, B., 2008, Short-range acoustic propagation variability on a shelf area with strong nonlinear internal waves, OCEANS 2008-MTS/IEEE Kobe Techno-Ocean, IEEE.
17
Roberts,J., 1975, Internal gravity waves in the ocean, AlaskaUniv College Inst Of Marine Science.
18
Ross, T. and Lavery,A., 2009, Laboratory observations of double-diffusive convection using high-frequency broadband acoustics, Experiments in Fluids, 46(2), 355-364.
19
Rubenstein, D., 1999, Observation of cnoidal internal waves and their effect on pagation in shallow water, IEEE J. Ocean Eng., 24(3), 346-357.
20
Rutenko, A., 2005, The effect of internal waves on the sound propagation in the shelf zone of the sea of Japan in different seasons, Acoustical Physics, 51(4), 449-456.
21
Scotti, A. and Pineda,J., 2004, Observation of very large and steep internal waves of elevation near the Massachusetts coast, Geophysical research letters, 31(22).
22
Sutherland, B. and Linden,P., 2002, Internal wave excitation by a vertically oscillating elliptical cylinder, Physics of Fluids (1994-present), 14(2), 721-731.
23
Thorpe, S. A., 2005, The turbulent ocean, Cambridge University Press,pp 230.
24
Turgut, A., Orr, M. and Pasewark, B., 2007, Acoustic monitoring of the tide height and slope-water intrusion at the New Jersey Shelf in winter conditions, The Journal of the Acoustical Society of America, 121(5), 2534-2541.
25
Warn-Varnas, A.C., Chin-Bing, S.A., King, D.B., Hallock, Z. and Hawkins, J.A, 2003, Ocean-acoustic solitary wave studies and predictions, Surveys in Geophysics, 24(1), 39-79.
26
Zhou, J. X., Zhang, X.Z. and Rogers, P. H., 1991, resonant interaction of sound wave with internal solitons in the coastal zone, The Journal of the Acoustical Society of America, 90(4), 2042-2054.
27
ORIGINAL_ARTICLE
An evaluation of single-site and multi-site statistical downscaling of SDSM–DC in terms of indices of climate extremes (Case study: Midwest of Iran)
Two single and multi-site statistical downscaling methods of Statistical Downscaling Model–Decision Centric (SDSM–DC) for daily temperature and precipitation are evaluated at nine stations located in the mountainous region of Iran’s Midwest. SDSM is best described as a single-site model, but it can be extended to multi-site applications via conditional resampling (CR-SDSM, Wilby et al. 2003; Harpham and Wilby 2005). SDSM–DC (Wilby and Dawson 2013) is a hybrid of the stochastic weather generator and transfer function methods. Predictor selection is based on empirical relationships between GCM-scale predictors and single-site predictand variables. (Farajzadeh et al. 2015). Applying SDSM to multi-site daily rainfall downscaling includes two steps: (1) the daily rainfall and temperature at a “marker” site (in this study, the area average amounts) is first downscaled by the single-site SDSM; (2) Daily rainfall amounts are then “resampled from the empirical distribution of area averages, conditional on the large-scale atmospheric forcing and the stochastic error term. The actual daily rainfall is determined by mapping the modeled normal cumulative distribution value onto the observed cumulative distribution of amounts at the marker site” (Wilby et al. 2003; Liu et al. 2013). Ultimately, the marker site rainfall is resampled to the constituent amount falling on the same day from each station in the multi-sites array (Harpham and Wilby 2005). Thus, if the marker series is based on an unweighted average of all sites, the conditional resampling will preserve both the areal average of the marker series and the spatial covariance of the multi-site rainfall (Wilby et al. 2003). Additionally, using area average, instead of individual sites as the marker series, reduces the risk of employing a nonhomogeneous/non-representative record and increases the signal to noise ratio of the predictand (Wilby et al. 2003; Liu et al. 2013). To downscale temperature, the same steps are applied but unconditionally using transfer function methods.For statistical downscaling, two sets of data are generally required: (1) observational data for model calibration and validation, as predictands; and (2) synoptic-scale climate data from GCM and/or reanalysis, as predictors. In order for a better assessment of climate variability and change on local and regional scale, long-term time series of reliable climate data at fine-scale resolution are required (Vincent et al 2002; Mekis and Vincent 2011; Menne et al 2012). As mentioned before, for the Midwest of Iran, we selected nine synoptic stations with nearly complete data coverage for 1981–2010.We used station data from two decades (1981–2000) for calibration and from one decade (2001–2010) for validation of daily values of minimum and maximum temperature, and total daily precipitation. To assess the accuracy and homogeneity of the observational data, we used different methods for quality control: the R packages RHtestsV3 (Wang and Feng 2010) and RHtests_dlyPrcp (Wang et al. 2010), based on penalized maximal t and F tests (Wang et al. 2007; Wang 2008b) that are embedded in a recursive testing algorithm (Wang 2008a); the R package Climatol (Guijarro 2012), which applies a type II linear regression model; and SDSM (Wilby and Dawson 2012, 2013) based on reanalysis predictor variables. Missing values are filled in by using the sequential k-nearest neighbor imputation method (Kim and Yi 2008) and homogeneity tests are applied both before and after infilling to assess infilling performance.Predictor fields are extracted from the National Centers for Environmental Prediction (NCEP) Reanalysis (Kalnay et al. 1996) archives at resolutions of 2.5°×2.5°. As mentioned earlier, SDSM has its own methodology for predictor selection in which EOFs of NCEP reanalysis data over the domain (30° N, 42° E) and (40° N, 52° E) are screened separately for temperature and for precipitation. (Farajzadeh et al. 2015)Results indicated that the methods are of widely varying complexity, with input requirements that range from single point predictors of temperature and precipitation to multivariate synoptic-scale fields. The period 1981-2000 is used for model calibration and 2001–2010 for validation, with performance assessed in terms of 27 Climate Extremes Indices (CLIMDEX). The sensitivity of the methods to large-scale anomalies and their ability to replicate the observed data distribution in the validation period are separately tested for each index by Pearson correlation and Kolmogorov–Smirnov (KS) tests, respectively. Combined tests are used to assess overall model performances. Single (multi)-site method of SDSM, passing 76%(81%), 16%(7%) and 14% (5%) of the Kolmogorov–Smirnov (KS), the Pearson correlation and the combined tests, performed well in terms of temperature and precipitation downscaling. Single-site method performed better than multi-site one at single sites; however, multisite method performance is better at regional downscaling. Correlation tests were passed less frequently than KS tests. Both methods downscaled temperature indices better than precipitation indices. Some indices, notably R20, R25, SDII, CWD, and TNx, were not successfully simulated by any of the methods. Model performance varied widely across the study region.
https://jesphys.ut.ac.ir/article_57734_1e25641f495050f03992ff628b89bce5.pdf
2017-04-21
193
208
10.22059/jesphys.2017.57734
"Single-site and multi-site downscaling"
"SDSM"
"climate extremes"
"Pearson correlation and Kolmogorov–Smirnov (KS) tests"
"Iran’s Midwest"
Ruhollah
Oji
oji_r@yahoo.com
1
Assistant professor of Climatology / University of Guilan
LEAD_AUTHOR
M.
Farajzadeh
farajzam2000@gmail.com
2
Tarbiat Modares University
AUTHOR
Y.
Ghavidel Rahimi
ghavidel@modares.ac.ir
3
Tarbiat Modares University
AUTHOR
A.
Massah Bavani
armassah@yahoo.com
4
University of Tehran
AUTHOR
اوجی ر.، 1392، تحلیل عدمقطعیت روشهای تکایستگاهی و چندایستگاهی در ریزگردانی مقادیر حدی دما و بارش. رساله دکتری، دانشگاه تربیت مدرس.
1
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2
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51
ORIGINAL_ARTICLE
Numerical solution of the shallow water equations using fourth-order compact MacCormack scheme
Shallow water equations are a model to present the behavior of a single-layer fluid with constant density, that the hydrostatic approximation has been applied. These equations for the motion of a dry and inviscid atmosphere with constant density include the momentum and the continuity equations. In addition, the shallow water equations are often used as a testbed to assess the performance of new numerical algorithms.In recent years, the trend toward increasing the accuracy of the numerical simulations of the atmospheric and oceanic motions has increased due to the inherent complexity in these motions. In recent researches, the compact schemes have been noticed because of their remarkable performance in the numerical simulation of fluid flows in other branches of fluid dynamics.This work is devoted to the application of the fourth-order compact MacCormack scheme to numerical solution of the conservative form of the two dimensional shallow water equations. The compact MacCormack method is formulated in form of a two-point scheme. Two versions of the fourth-order compact MacCormack scheme have been introduced and called as 4/2 and 4/4. The first order spatial derivative operators have implicit forms in both schemes (4/2 and 4/4), for one-sided forward and backward operators. The MacCormack scheme uses two time-marching methods: The first is the original two-stage method and the other one is the Runge-Kutta-type (RK2, RK4 and LDDRK4-6) method.In the present work first, we solve a simple linear (advection) equation with an analytical solution, using the second-order and the fourth-order compact MacCormack-type schemes (with the original and the Runge-Kutta time-marching methods) and compare their global errors. The results show that when the fourth-order compact MacCormack schemes with the original time-marching are used, the 4/2 formulation has better results than the 4/4 formulation, but when these schemes use the Runge-Kutta time-marching, the results of the 4/4 formulation are better than those in the 4/2 formulation. According to these results and the magnitude of the global errors, we used four MacCormack-type methods to solve the shallow water equations. The methods are the second-order scheme with the original time-marching, the 4/2 type of fourth order compact scheme with both the original and the RK4 time-marching, and the 4/4 type of fourth order compact scheme with the RK4 time-marching.In the following, we solved the conservative form of the one-dimensional shallow water equations with those four mentioned schemes. The results were compared with a test case with known analytical solution.At last, we solved the conservative form of the two-dimensional shallow water equations. To perform the simulations two well know test cases are used. To assess the numerical accuracy, we estimated conservative quantities such as energy, enstrophy and mass along the simulation process in all time steps. The estimated results indicate that the fourth-order compact MacCormack schemes retain the conservation of these quantities better than the second-order MacCormack scheme. In comparison with the other applied schemes in this work, while the 4/4 formulation with the RK4 time-marching shows more accurate results, the numerical stability condition of this scheme is less than the other schemes. In the second test case, we point out that the computational time of the code for each numerical solution, which utilizes the fourth-order compact schemes, is longer than the computational time of the solution using second-order scheme; but their implementation is reasonable because their numerical accuracy is higher than that of the second-order scheme.
https://jesphys.ut.ac.ir/article_58911_eae5a90775ac4732862a54cfe30d4388.pdf
2017-04-21
209
228
10.22059/jesphys.2017.58911
Shallow water equations
Compact MacCormack scheme
Numerical accuracy
Runge-Kutta
Rasoul
Mirzaei-Shiri
r_mirzaei@ut.ac.ir
1
دانشجوی دکترای هواشناسی مؤسسه ژئوفیزیک دانشگاه تهران
AUTHOR
سرمد
قادر
sghader@ut.ac.ir
2
مؤسسه ژئوفیزیک دانشگاه تهران
LEAD_AUTHOR
مجید
مزرعه فراهانی
mazraeh@ut.ac.ir
3
مؤسسه ژئوفیزیک دانشگاه تهران
AUTHOR
عباسعلی
علی اکبری بیدختی
bidokhti@ut.ac.ir
4
مؤسسه ژئوفیزیک دانشگاه تهران
AUTHOR
جوان نژاد، ر.، مشکواتی، ا. ح.، قادر، س. و احمدی گیوی، ف.، 1395، حل عددی شکل پایستار معادلات تراکمپذیر دوبعدی و ناآبایستایی جو با روش فشرده مککورمک، م. ژئوفیزیک ایران، در حال چاپ.
1
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2
قادر، س. و اصفهانیان، و.، 1385، حل عددی شکل پایستار معادلات آب کمعمق با استفاده از روش ابرفشرده مرتبه ششم، م. فیزیک زمین و فضا، 32(2)، 44-31.
3
قادر، س.، بیدختی، ع. ع. و فلاحت، س.، 1389، حل عددی مسئله تنظیم راسبی غیرخطی ناپایای دوبعدی با استفاده از روش فشرده مککورمک مرتبه چهارم، م. فیزیک زمین و فضا، 36(3)، 173-151.
4
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5
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