Institute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421The dynamics of cyclonic systems over Iran using potential vorticity diagnostics: A case study for Nov-Dec 2003The dynamics of cyclonic systems over Iran using potential vorticity diagnostics: A case study for Nov-Dec 20031138003310.22059/jesphys.2006.80033FAFarhangAhmadi GiviInstitute of Geophysics, University of TehranAli RezaMohebalhojehInstitute of Geophysics, University of TehranMaryamGharaylouInstitute of Geophysics, University of TehranJournal Article20210228Potential vorticity (PV) is one of the dynamical parameters which is used in the study of weather system dynamics. It is conserved in the absence of friction and diabatic processes and therefore it can be used as a dynamical tracer in the formation and development of cyclonic systems. In this study we attempt to investigate the dynamic of cyclogenesis over the Middle-East and Iran for the period of Nov-Dec 2003, within the potential vorticity framework. It is aimed to study qualitatively and quantitatively the role of different mechanisms which have been involved in the cyclone development throughout the life cycle of the cyclone.
At first, using the NOAA analysis dataset, six hourly geopotential height maps for the period of Nov-Dec 2003 were examined. Only one noticeable cyclogenesis event with clear life cycle was found, beginning at 0000UTC 4 December and ending at 0600UTC 9 December 2003. The results suggest that the main reason that there was only one intense cyclone in the period studied here can be related to the occurrence of two significant blocking systems at the beginning and at the end of this period. As we expect, these blockings act to place stable weather conditions in the east and consequently to inhibit the cyclone development.
In the second stage, the Ertel-Rossby PV was calculated every six hours using the NOAA analysis dataset. The data used in the calculation of PV includes the horizontal wind components and potential temperature fields at 20 pressure levels with 50 hPa interval. Then the potential vorticity fields at pressure levels were interpolated to relevant isentropic surfaces, in order to study the contributions of the upper-level, mid-level, and surface PV anomalies in the cyclone development. To support the results, the vertical motions at 700 hPa were also used.
In general, three stages of cyclogenesis can be identified in the life cycle of the cyclone studied here. The results show that the upper-level PV anomaly plays the main role in the low-level disturbance development during the incipient stage, without remarkable contributions from the other PV anomalies. In the intensification stage, in addition to the upper-level PV anomaly both the thermal advection and the diabatically generated PV at low levels contribute significantly to the surface cyclogenesis. The results also suggest that there is interaction among the upper-level and low-level PV anomalies at this stage. Finally, the mature stage of cyclogenesis is encountered with the decay and breaking of the PV anomalies.Potential vorticity (PV) is one of the dynamical parameters which is used in the study of weather system dynamics. It is conserved in the absence of friction and diabatic processes and therefore it can be used as a dynamical tracer in the formation and development of cyclonic systems. In this study we attempt to investigate the dynamic of cyclogenesis over the Middle-East and Iran for the period of Nov-Dec 2003, within the potential vorticity framework. It is aimed to study qualitatively and quantitatively the role of different mechanisms which have been involved in the cyclone development throughout the life cycle of the cyclone.
At first, using the NOAA analysis dataset, six hourly geopotential height maps for the period of Nov-Dec 2003 were examined. Only one noticeable cyclogenesis event with clear life cycle was found, beginning at 0000UTC 4 December and ending at 0600UTC 9 December 2003. The results suggest that the main reason that there was only one intense cyclone in the period studied here can be related to the occurrence of two significant blocking systems at the beginning and at the end of this period. As we expect, these blockings act to place stable weather conditions in the east and consequently to inhibit the cyclone development.
In the second stage, the Ertel-Rossby PV was calculated every six hours using the NOAA analysis dataset. The data used in the calculation of PV includes the horizontal wind components and potential temperature fields at 20 pressure levels with 50 hPa interval. Then the potential vorticity fields at pressure levels were interpolated to relevant isentropic surfaces, in order to study the contributions of the upper-level, mid-level, and surface PV anomalies in the cyclone development. To support the results, the vertical motions at 700 hPa were also used.
In general, three stages of cyclogenesis can be identified in the life cycle of the cyclone studied here. The results show that the upper-level PV anomaly plays the main role in the low-level disturbance development during the incipient stage, without remarkable contributions from the other PV anomalies. In the intensification stage, in addition to the upper-level PV anomaly both the thermal advection and the diabatically generated PV at low levels contribute significantly to the surface cyclogenesis. The results also suggest that there is interaction among the upper-level and low-level PV anomalies at this stage. Finally, the mature stage of cyclogenesis is encountered with the decay and breaking of the PV anomalies.https://jesphys.ut.ac.ir/article_80033_e664ba95b6002139cb3ccbf6f68b3fd0.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Alluvium dominant period determination by microtremors in the North-western TehranAlluvium dominant period determination by microtremors in the North-western Tehran15268003410.22059/jesphys.2006.80034FAMohammad KazemHafiziInstitute of Geophysics, University of Tehran0000-0002-5634-1141ElyasNaderiآموزش و پرورش ایران دبیJournal Article20210228Alluvium responses to earthquake motion interference to the damage creation of structure is illustrated in different ways. One of the most important casualty effect that we can refer to is resonance phenomenon. This occurs when the natural period of a Alluvium is equal to the natural period of bedrock. Under these conditions the effect of amplification in ground motion acceleration is maximum.
In this research the microtremor measurements for determination of the natural period of a Alluvium, performed in the NS direction profile in north-western Tehran at 6 stations one of which is located on a bedrock outcrop. Interpretation of data based on the amplitude spectrum, was performed by two methods. In the first method called the bedrock reference station, the average amplitude spectrum of the horizontal components and the vertical component of the station on Alluvium is divided by the average amplitude spectrum of the horizontal and vertical components of the station on the bedrock. In the second method, the Nakamura method, the average amplitude spectrum of the horizontal components are divided by the amplitude spectrum of the vertical component of the same station.
The processing and interpretation of field data show that the bedrock reference station method for calculation of a Alluvium resonance frequency has a better validity than the Nakamura method. Resonance frequency in this area is between 2.4 to 5.5 Hz which reduces from north to south. So the natural period of Alluvium in the profile increases from north to south, which agrees with the increase in thickness of alluvial deposits in the area.
Therefore, microtremor measurements based upon the bedrock reference station method from an economical aspect and to minimize time, are suggested for the determination of the Alluvium natural period.Alluvium responses to earthquake motion interference to the damage creation of structure is illustrated in different ways. One of the most important casualty effect that we can refer to is resonance phenomenon. This occurs when the natural period of a Alluvium is equal to the natural period of bedrock. Under these conditions the effect of amplification in ground motion acceleration is maximum.
In this research the microtremor measurements for determination of the natural period of a Alluvium, performed in the NS direction profile in north-western Tehran at 6 stations one of which is located on a bedrock outcrop. Interpretation of data based on the amplitude spectrum, was performed by two methods. In the first method called the bedrock reference station, the average amplitude spectrum of the horizontal components and the vertical component of the station on Alluvium is divided by the average amplitude spectrum of the horizontal and vertical components of the station on the bedrock. In the second method, the Nakamura method, the average amplitude spectrum of the horizontal components are divided by the amplitude spectrum of the vertical component of the same station.
The processing and interpretation of field data show that the bedrock reference station method for calculation of a Alluvium resonance frequency has a better validity than the Nakamura method. Resonance frequency in this area is between 2.4 to 5.5 Hz which reduces from north to south. So the natural period of Alluvium in the profile increases from north to south, which agrees with the increase in thickness of alluvial deposits in the area.
Therefore, microtremor measurements based upon the bedrock reference station method from an economical aspect and to minimize time, are suggested for the determination of the Alluvium natural period.https://jesphys.ut.ac.ir/article_80034_4d422bf03985a8991e9fa629e662f6ea.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Spatial uncertainty reducing in M8 algorithm using potential earthquake sourcesSpatial uncertainty reducing in M8 algorithm using potential earthquake sources27368003510.22059/jesphys.2006.80035FANavidShadmanamanInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranNoorbakhshMirzaeiInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, Iran0000-0002-7931-2669AbdolrezaGhodsInstitute for Advanced Studies in Basic Sciences (IASBS) P.O. Box 451195-1159AliNegarestaniAtomic Energy Organization of Iran, P.O. Box 14155-1339ForoghKeshvariInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranJournal Article20210228M8 algorithm is a well-known method for intermediate-term earthquake prediction. The predicted area by M8 algorithm includes relatively extensive territory. Since earthquakes occur in places where enough potential for accumulating stress exists, by limiting the predicted area to them, spatial uncertainty of M8 algorithm can be reduced. In this work, at first, we tested this method for the Rudbar and Bam earthquakes as M8 algorithm could predict them well. Then, areas of forward (future) earthquake prediction by M8 algorithm were tested by this method. The results show considerable reduction of predicted area using potential earthquake sources.M8 algorithm is a well-known method for intermediate-term earthquake prediction. The predicted area by M8 algorithm includes relatively extensive territory. Since earthquakes occur in places where enough potential for accumulating stress exists, by limiting the predicted area to them, spatial uncertainty of M8 algorithm can be reduced. In this work, at first, we tested this method for the Rudbar and Bam earthquakes as M8 algorithm could predict them well. Then, areas of forward (future) earthquake prediction by M8 algorithm were tested by this method. The results show considerable reduction of predicted area using potential earthquake sources.https://jesphys.ut.ac.ir/article_80035_93603072e4f5f6b0ad10a46062006477.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Intermediate earthquake prediction in Iran by M8 algorithmIntermediate earthquake prediction in Iran by M8 algorithm37488006310.22059/jesphys.2006.80063FANavidShadmanamanInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranNorbakhshMirzaeiInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, Iran0000-0002-7931-2669AbdolrezaGhodsInstitute for Advanced Studies in Basic Sciences (IASBS) P.O. Box 451195-1159ForoghKeshvariInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranJournal Article20210301The M8 algorithm for earthquake prediction is used for intermediate-term prediction of large earthquakes (M6.5) in Iran. The M8 algorithm analyzes premonitory seismic activities prior to the occurrence of large earthquakes. The seismic precursors are used to identify times of increased probability (TIP) for a given region. Duration of each TIP or alarm announced by M8 algorithm is 5 years that includes the area several times larger than the causative earthquake source. Up to now, several large earthquakes have been successfully predicted by M8 algorithm in the world. In this work, forward earthquake predictions are tested in Iranian territory using this algorithm. The M8 algorithm identifies candidate areas for oncoming earthquakes. These TIPs include areas of the west and southwest of Iran.The M8 algorithm for earthquake prediction is used for intermediate-term prediction of large earthquakes (M6.5) in Iran. The M8 algorithm analyzes premonitory seismic activities prior to the occurrence of large earthquakes. The seismic precursors are used to identify times of increased probability (TIP) for a given region. Duration of each TIP or alarm announced by M8 algorithm is 5 years that includes the area several times larger than the causative earthquake source. Up to now, several large earthquakes have been successfully predicted by M8 algorithm in the world. In this work, forward earthquake predictions are tested in Iranian territory using this algorithm. The M8 algorithm identifies candidate areas for oncoming earthquakes. These TIPs include areas of the west and southwest of Iran.https://jesphys.ut.ac.ir/article_80063_a83518cbc4bea7aef15b794652a2922f.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Thermodynamic study of the troposphere over the Middle East region for the period of 1980-1993Thermodynamic study of the troposphere over the Middle East region for the period of 1980-199349658006410.22059/jesphys.2006.80064FAFarhangAhmadi-GiviInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranShirinDastmalchi TabriziInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranJournal Article20210301Using the NASA reanalysis data the thermodynamic structure of the troposphere over the Middle East region is investigated for a period of 14 years (1980-1993). The calculated quantities consist of the monthly mean of specific humidity and temperature, temperature and humidity fluxes for January and July at 850 and 700 hPa. In addition, the time series of specific humidity and temperature for Tehran/ Iran have also been studied for the 14-year time period. The area examined extends between 20˚ and 60˚ N and between 0 and 90˚ E.
The results show that under normal conditions three major sources of humidity which can affect the Middle East region are seen to the south of the domain here, located over North Africa, east of the Red Sea, and the western part of the Indian Ocean. The analysis of the monthly mean specific humidity distribution along with its fluxes suggests that the main part of the humidity over the south of Iran comes from the source located to the east of the Red Sea. The humidity source observed in North Africa exhibits remarkable annual changes and it disappears in some years, especially when the El-Nina phenomenon occurs.
The other humidity source and noticeable humidity fluxes that can affect the Middle East region and the central and northern parts of Iran is connected with the intense humidity fluxes over the east of the domain examined here. These humidity fluxes, which originate over the Atlantic Ocean, can be reinforced significantly as they move southward over the Mediterranean basin and then extend eastward over the Middle East. It is shown that the maximum specific humidity over Iran is connected with the existence of intense sources of humidity located over the east of the Red Sea and the western part of the Indian Ocean and seems to be related to the occurrence of intense the Indian monsoon. The results of time series of temperature and humidity during the whole period indicate that the seasonal changes of temperature are much greater in winter as compared with summer whereas the seasonal changes of specific humidity are much greater in summer as compared with winter. Our analysis suggest that the occurrences of El-Nino and La-Nina may have effects on the changes of the specific humidity in July and January, and La-Nina’s effect seems to be greater, as compared with El-Nino’s.
The monthly mean temperature distribution and its fluxes also show that three cold centers can be identified in the Northern Hemisphere, located over Greenland, Northern America, and the north of Asia. It seems the temperature distribution over the Middle East and Iran are affected mainly by the cold center over Greenland.Using the NASA reanalysis data the thermodynamic structure of the troposphere over the Middle East region is investigated for a period of 14 years (1980-1993). The calculated quantities consist of the monthly mean of specific humidity and temperature, temperature and humidity fluxes for January and July at 850 and 700 hPa. In addition, the time series of specific humidity and temperature for Tehran/ Iran have also been studied for the 14-year time period. The area examined extends between 20˚ and 60˚ N and between 0 and 90˚ E.
The results show that under normal conditions three major sources of humidity which can affect the Middle East region are seen to the south of the domain here, located over North Africa, east of the Red Sea, and the western part of the Indian Ocean. The analysis of the monthly mean specific humidity distribution along with its fluxes suggests that the main part of the humidity over the south of Iran comes from the source located to the east of the Red Sea. The humidity source observed in North Africa exhibits remarkable annual changes and it disappears in some years, especially when the El-Nina phenomenon occurs.
The other humidity source and noticeable humidity fluxes that can affect the Middle East region and the central and northern parts of Iran is connected with the intense humidity fluxes over the east of the domain examined here. These humidity fluxes, which originate over the Atlantic Ocean, can be reinforced significantly as they move southward over the Mediterranean basin and then extend eastward over the Middle East. It is shown that the maximum specific humidity over Iran is connected with the existence of intense sources of humidity located over the east of the Red Sea and the western part of the Indian Ocean and seems to be related to the occurrence of intense the Indian monsoon. The results of time series of temperature and humidity during the whole period indicate that the seasonal changes of temperature are much greater in winter as compared with summer whereas the seasonal changes of specific humidity are much greater in summer as compared with winter. Our analysis suggest that the occurrences of El-Nino and La-Nina may have effects on the changes of the specific humidity in July and January, and La-Nina’s effect seems to be greater, as compared with El-Nino’s.
The monthly mean temperature distribution and its fluxes also show that three cold centers can be identified in the Northern Hemisphere, located over Greenland, Northern America, and the north of Asia. It seems the temperature distribution over the Middle East and Iran are affected mainly by the cold center over Greenland.https://jesphys.ut.ac.ir/article_80064_fd78c0b19aab1c0382338f5555f0d909.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Estimation of source parameters, attenuation and spectral decay parameter by spectral method from recorded accelerograms during the Bam earthquake (2003)Estimation of source parameters, attenuation and spectral decay parameter by spectral method from recorded accelerograms during the Bam earthquake (2003)67758006610.22059/jesphys.2006.80066FAHabibRahimiInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, Iran0000-0002-2085-1043NasrollahKamalianInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranHadiGhasemiInternational Institute of Earthquake Engineering and Seismology, P. O. Box 19395-3913 Tehran, IranJournal Article20210301The Bam earthquake on 26 December, 2003 with a magnitude (Ms=6.8; mb=6) in southeastern Iran occurred in a populated area, and the main shock recorded in 23 strong motion acceleration building house research center (BHRC).
In this study, strong motion records are used to obtain an estimate of source parameters, high frequency attenuation and spectral decay parameter for 9 stations from 22 stations that have S/N rate good.
The source parameters are obtained by fitting the data by a dislocation source model combined with an exponential model for the attenuation. The source parameter estimated here
and estimated moment magnitude agree well with values obtained previously from Harvard university by the CMT method.
The high frequency attenuation obtained by used from the Amplitude spectral method that can be written as
Where is geometrical spreading.
Estimates of path averaged crustal shear wave quality factors give results in the range 77 to 730, and mean of spectral decay parameters kappa= 0.08 sec for two horizontal componentsThe Bam earthquake on 26 December, 2003 with a magnitude (Ms=6.8; mb=6) in southeastern Iran occurred in a populated area, and the main shock recorded in 23 strong motion acceleration building house research center (BHRC).
In this study, strong motion records are used to obtain an estimate of source parameters, high frequency attenuation and spectral decay parameter for 9 stations from 22 stations that have S/N rate good.
The source parameters are obtained by fitting the data by a dislocation source model combined with an exponential model for the attenuation. The source parameter estimated here
and estimated moment magnitude agree well with values obtained previously from Harvard university by the CMT method.
The high frequency attenuation obtained by used from the Amplitude spectral method that can be written as
Where is geometrical spreading.
Estimates of path averaged crustal shear wave quality factors give results in the range 77 to 730, and mean of spectral decay parameters kappa= 0.08 sec for two horizontal componentshttps://jesphys.ut.ac.ir/article_80066_cc74eadb9f2283c7dacca3d861c170f1.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Pore compressibility of heterogeneous carbonate rocks in the Asmari formationPore compressibility of heterogeneous carbonate rocks in the Asmari formation77838006710.22059/jesphys.2006.80067FAEzatollahKazemzadehResearch Institute of Petroleum Industry, RIPI, P.O. Box 18745-4163MajidNabi-BidhendiInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, Iran0000-0002-9555-8327HesamAloki BakhtiariResearch Institute of Petroleum Industry, RIPI, P.O. Box 18745-4163Mohammad RezaRezaeeScience Department, University of Tehran, P.O. Box 14155-6455Journal Article20210301Compressibility of hydrocarbon reservoir rocks is a key parameter, which affects reservoir, seismic and mechanical properties. The objective of the present study is the investigation of pore compressibility with changes on net confining pressure in the carbonate rocks. For this purpose the effects of texture, pore geometry and porosity values on pore compressibility have been analyzed. A total number of 90 samples of Asmari formation carbonates were selected from an oil field in the south of Iran. After geological study and grouping of the samples based on texture and pore geometry, the relation between pore compressibility and net confining pressure has been presented by an equation for each group of rocks.Compressibility of hydrocarbon reservoir rocks is a key parameter, which affects reservoir, seismic and mechanical properties. The objective of the present study is the investigation of pore compressibility with changes on net confining pressure in the carbonate rocks. For this purpose the effects of texture, pore geometry and porosity values on pore compressibility have been analyzed. A total number of 90 samples of Asmari formation carbonates were selected from an oil field in the south of Iran. After geological study and grouping of the samples based on texture and pore geometry, the relation between pore compressibility and net confining pressure has been presented by an equation for each group of rocks.https://jesphys.ut.ac.ir/article_80067_4022e00dceedb5aa0fb7454bca2a9e6b.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421A case study of clear air turbulence over Iran using turbulence indices for the period January to May 2004A case study of clear air turbulence over Iran using turbulence indices for the period January to May 2004851028006810.22059/jesphys.2006.80068FASaharTajbakhshIslamic Azad University, Science and Research Sector, P.O.Box 14515-775, TehranMajidAzadiMeteorological and Atmospheric Research Center, P. O. Box 14155-6466,Tehran0000-0002-5991-9703Abbas AliA. BidokhtiInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranParvinArabliIslamic Republic of Iran Meteorological Organization, P. O. Box 14155-6466,TehranJournal Article20210301An attempt is made to calculate some important quantities, such as wind shear, related to clear air turbulence (CAT) and their associated turbulence indices. Thresholds of the indices are calculated for moderate and light to moderate cases of CATs over Iran for a five months period (from January to May 2004) and corresponding large scale atmospheric patterns at upper levels have been examined. Indices are calculated using AVN model outputs and compared with pilot reports for CAT. Results showed that occurrence of CAT with intensity more that moderate is very rare over the region. Threshold values of Elrod-2 and Dutton are in good agreement with values calculated over Europe and USA. Most of the turbulence occurs in 250-300 hPa layer. Also, it was seen that above the geopotential trough the condition is favorable for the formation of intense CATs.An attempt is made to calculate some important quantities, such as wind shear, related to clear air turbulence (CAT) and their associated turbulence indices. Thresholds of the indices are calculated for moderate and light to moderate cases of CATs over Iran for a five months period (from January to May 2004) and corresponding large scale atmospheric patterns at upper levels have been examined. Indices are calculated using AVN model outputs and compared with pilot reports for CAT. Results showed that occurrence of CAT with intensity more that moderate is very rare over the region. Threshold values of Elrod-2 and Dutton are in good agreement with values calculated over Europe and USA. Most of the turbulence occurs in 250-300 hPa layer. Also, it was seen that above the geopotential trough the condition is favorable for the formation of intense CATs.https://jesphys.ut.ac.ir/article_80068_20683b0e788b4a7635e0c5cac2e74bbc.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Application of geostatistical methods for climatic classification (A case study, Ourmieh lake basin)Application of geostatistical methods for climatic classification (A case study, Ourmieh lake basin)1031168006910.22059/jesphys.2006.80069FAMahyarMehdizadehAgrometeorologystMohammad HoseinMahdianAssistant professor, Soil conservation and watershed management research center, P.O. Box 13445-1136SohrabHajjamInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranJournal Article20210301Spatial analysis of temperature and rainfall is necessary in many natural resources studies including water resource improvements, management, modeling and irrigation. In order to determine spatial variability of temperature and rainfall, classic statistical methods are usually applied. These methods may lead to imprecision results because; they do not include data arrangement and location perfectly.
In the present research, three methods were used to estimate regional rainfall and temperature using geostatistics and geographic information system. These methods consist of Thin Plate Smoothing Spline (TPSS), with the power of 2, 3, 4 and 5, with and without elevation as co variable; Kriging (ordinary kriging and co kriging) and Weighted Moving Average (WMA) with the power of 1, 2, 3, 4, and 5. These methods were applied to a thirty years data set of the Ourmieh lake basin in the north west of Iran. Mean Absolute Errors (MAE) and Mean Bias Errors (MBE) were used as comparison criteria.
It was found that the TPSS method with a power of 2 and without co variable (elevation) is an appropriate method to estimate annual rainfall. Kriging and WMA methods are the second and third best methods, respectively. The same results are applicable for monthly rainfall most months.
For temperature estimation, the TPSS method with a power of 2 and with elevation as co variable was the best method and co kriging, kriging and WMA were second, third and fourth best methods, respectively.
By comparing geostatistical results with those calculated by the gradient method, a higher precision was obtained using geostatistical methods for considered variable in the area studied. Finally, the climate of the area studied, was scaled as semi arid and humid using the Selianinov climatic classification method. Geographical distribution of rainfall and annual sum of active temperature with based value of 10 C were used for the method mentioned.Spatial analysis of temperature and rainfall is necessary in many natural resources studies including water resource improvements, management, modeling and irrigation. In order to determine spatial variability of temperature and rainfall, classic statistical methods are usually applied. These methods may lead to imprecision results because; they do not include data arrangement and location perfectly.
In the present research, three methods were used to estimate regional rainfall and temperature using geostatistics and geographic information system. These methods consist of Thin Plate Smoothing Spline (TPSS), with the power of 2, 3, 4 and 5, with and without elevation as co variable; Kriging (ordinary kriging and co kriging) and Weighted Moving Average (WMA) with the power of 1, 2, 3, 4, and 5. These methods were applied to a thirty years data set of the Ourmieh lake basin in the north west of Iran. Mean Absolute Errors (MAE) and Mean Bias Errors (MBE) were used as comparison criteria.
It was found that the TPSS method with a power of 2 and without co variable (elevation) is an appropriate method to estimate annual rainfall. Kriging and WMA methods are the second and third best methods, respectively. The same results are applicable for monthly rainfall most months.
For temperature estimation, the TPSS method with a power of 2 and with elevation as co variable was the best method and co kriging, kriging and WMA were second, third and fourth best methods, respectively.
By comparing geostatistical results with those calculated by the gradient method, a higher precision was obtained using geostatistical methods for considered variable in the area studied. Finally, the climate of the area studied, was scaled as semi arid and humid using the Selianinov climatic classification method. Geographical distribution of rainfall and annual sum of active temperature with based value of 10 C were used for the method mentioned.https://jesphys.ut.ac.ir/article_80069_20674804789a8730e6c65507d6adf623.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421The Iranian geoid by high-degree ellipsoidal Stokes integralThe Iranian geoid by high-degree ellipsoidal Stokes integral158007010.22059/jesphys.2006.80070FAVahidE. ArdestaniInstitute of Geophysics, University of Tehran, P.O. Box 14155- 6466, Tehran, IranJournal Article20210301The high-degree ellipsoidal Stokes integral (Ardestani and Martinec, 2003a) is used to compute the geoidal heights over a territory in Iran. To compute the low-degree part of the geoidal heights a global geopotential model (EGM96) is used and for the high-degree part, the solution of the ellipsoidal Stokes boundary-value problem (BVP) in the form of surface integral is applied.
Therefore the geoidal heights con be calculated for a part of Iranian territory where the data is available.The high-degree ellipsoidal Stokes integral (Ardestani and Martinec, 2003a) is used to compute the geoidal heights over a territory in Iran. To compute the low-degree part of the geoidal heights a global geopotential model (EGM96) is used and for the high-degree part, the solution of the ellipsoidal Stokes boundary-value problem (BVP) in the form of surface integral is applied.
Therefore the geoidal heights con be calculated for a part of Iranian territory where the data is available.https://jesphys.ut.ac.ir/article_80070_21f5e614ffe334b8b7a56c2f36820da2.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421A hybrid precise gravimetric geoid model for Iran based on recent GRACE and SRTM data and the least squares modification of Stokes’s formulaA hybrid precise gravimetric geoid model for Iran based on recent GRACE and SRTM data and the least squares modification of Stokes’s formula7238007110.22059/jesphys.2006.80071FARaminKiamehrGeodesy Group, Royal Institute of Technology, SE -100 44 Stockholm, Sweden and
Department of Geomatics, Zanjan University, 313, Zanjan, IranJournal Article20210301Since 1986, several gravimetric geoid models have been published in the Iran region. It was found that the standard deviation of fitting between these models versus GPS/levelling data in most cases was worse than the currently available global geopotential models. A new hybrid gravimetric geoid model computed (IRG04) by using the least squares modification of Stokes formula based on the recent published GRACE based global geopotential model, the high-resolution Shuttle SRTM global digital terrain model and a new Iranian gravity anomaly database. The absolute and relative accuracies of the new geoid model tested versus the GPS/levelling points and they are estimated about 0.27 m and 3.8 ppm, respectively. Additional comparison between the IRG04 and the recent published gravimetric geoid models shows that the relative accuracy of the IRG04 is almost 4 times better than the most recent published models in this area.Since 1986, several gravimetric geoid models have been published in the Iran region. It was found that the standard deviation of fitting between these models versus GPS/levelling data in most cases was worse than the currently available global geopotential models. A new hybrid gravimetric geoid model computed (IRG04) by using the least squares modification of Stokes formula based on the recent published GRACE based global geopotential model, the high-resolution Shuttle SRTM global digital terrain model and a new Iranian gravity anomaly database. The absolute and relative accuracies of the new geoid model tested versus the GPS/levelling points and they are estimated about 0.27 m and 3.8 ppm, respectively. Additional comparison between the IRG04 and the recent published gravimetric geoid models shows that the relative accuracy of the IRG04 is almost 4 times better than the most recent published models in this area.https://jesphys.ut.ac.ir/article_80071_d9262f84f79c53a45c7b12e9b4d33005.pdfInstitute of Geophysics, University of TehranJournal of the Earth and Space Physics2538-371X32120060421Stochastic finite-fault simulation for the 2002 Changureh-Avaj earthquake, NW IranStochastic finite-fault simulation for the 2002 Changureh-Avaj earthquake, NW Iran25358007210.22059/jesphys.2006.80072FAHadiGhasemiBuilding and Housing Research Center, P.O. Box 13145-1696, Tehran, IranNasrollahKamalianInstitute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, IranHoseinHamzelooInternational Institute of Earthquake Engineering and Seismology, Tehran, IranJournal Article20210301Stochastic finite-fault simulation is used to simulate the acceleration time histories of the 22 June 2002 Changoureh-Avaj earthquake. The method generalizes the stochastic ground motion simulation technique, developed for point source, to the case of finite faults, in which the ground motion amplitudes are simulated as a summation of stochastic point source. Geometrical spreading and regional inelastic attenuation are included in the model. The strong motion simulations are performed by adjusting the sub-fault size to calibrate the simulation model against recorded ground motions. In this way the length of the fault is taken as 25 km and its width as 18 km, and the fault plane is divided into 5×3 elements. Considering that site amplification functions play an important role in the simulation process, site specific amplification function is estimated by the horizontal to vertical ratio technique. <br />A quite satisfactory agreement is found between the simulated amplitude Fourier spectra and the recorded data at frequencies of engineering interest (0.1 to 20 Hz) including the capability of the method to reproduce the salient ground motion characteristics.Stochastic finite-fault simulation is used to simulate the acceleration time histories of the 22 June 2002 Changoureh-Avaj earthquake. The method generalizes the stochastic ground motion simulation technique, developed for point source, to the case of finite faults, in which the ground motion amplitudes are simulated as a summation of stochastic point source. Geometrical spreading and regional inelastic attenuation are included in the model. The strong motion simulations are performed by adjusting the sub-fault size to calibrate the simulation model against recorded ground motions. In this way the length of the fault is taken as 25 km and its width as 18 km, and the fault plane is divided into 5×3 elements. Considering that site amplification functions play an important role in the simulation process, site specific amplification function is estimated by the horizontal to vertical ratio technique. <br />A quite satisfactory agreement is found between the simulated amplitude Fourier spectra and the recorded data at frequencies of engineering interest (0.1 to 20 Hz) including the capability of the method to reproduce the salient ground motion characteristics.https://jesphys.ut.ac.ir/article_80072_4a4bcc3ab184d05b610d30519abbe837.pdf