ORIGINAL_ARTICLE
Optical dating of Holocene lake bed sediments of the Nimbluk Plain, Khorasan, Northeast Iran: Implications for the climate change and palaeo-environment
We have investigated an optically stimulated luminescence (OSL) dating study in the Nimbluk lakebed in Khorasan, northeast Iran. Two samples of the lake-bed sediments from ~1 m below the land surface are successfully dated at 7.3-9.9 ka. All necessary experiments have been performed to choose the most suitable procedure for dating quartz extracts using single aliquot regeneration method (SAR). We have employed weighted histogram, unweighted histogram and central age model (CAM) for equivalent dose determination. Although, these results of the ages do not allow us to determine the timing of desiccation, the results suggest that the early part of the Holocene was much wetter than today. This provides valuable palaeo-environmental data in the region.
https://jesphys.ut.ac.ir/article_57222_149f138a655015a15b8f47bdbe7f3bc0.pdf
2015-12-22
1
12
10.22059/jesphys.2015.57222
Iran
Lake-bed sediments
Luminescence dating
Nimbulk Plain
OSL
Morteza
Fattahi
mfattahi@ut.ac.ir
1
Associate Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
LEAD_AUTHOR
Richard
Walker
richw@earth.ox.ac.uk
2
Department of Earth Sciences, University of Oxford, Parks Road, England
AUTHOR
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45
ORIGINAL_ARTICLE
Moment tensor and stress inversion for an active fault system in west part of Lut-Block, Iran
Iran is one of the most tectonically active regions on the Alpine-Himalayan earthquake belt. Eastern Iran, nowadays, is one of the most active regions of the country. The occurrence of several destructive earthquakes during the past 50 years provides the evidence for the seismic activity in this region. The earthquakes are mostly concentrated around the Lut-block. There are strike-slip fault systems with nearly north-south strike, east and west of the Lut-block. The fault system located in the west part of the Lut-block includes Tabas, Nayband, Lakarkuh, Gowk and Sabzevaran faults. This system is of great importance since it has generated destructive earthquakes such as Dasht-e-Bayaz. Since understanding the focal mechanism of the fault responsible for earthquake is one of the most important parameters, the accuracy to calculate the focal mechanism is extremely vital. Therefore, we have calculated focal mechanisms of the 34 recent earthquakes happened on this system using full moment tensor inversion. The waveform data from 8 broad-band stations, operated by International Institute of Earthquake Engineering and Seismology (IIEES), was used in this study. Appling ISOLated Asperities (ISOLA) package for the full moment tensor inversion using the local and regional data enables us to achieve a higher accuracy in determined focal mechanisms, in comparison with other methods which use teleseismic data. As the magnitude of these events are all smaller than 5.5 (the biggest one equals 5.2), it was not possible to obtain the focal mechanism of almost all of these events through CMT solutions using teleseismic data. The obtained focal mechanisms show that the main mechanism of the Nayband-Gowk-Sabzevaran system is right-lateral strike-slip with a reverse component. The trends of the three main stress axes were also calculated using the 32 focal mechanisms and the stress inversion technique. The results show that the second stress axis (σ2) is nearly vertical, which is one of the characteristics of the strike-slip regimes.
https://jesphys.ut.ac.ir/article_57223_49ac3d0092e83c3eb8542da34497e5b8.pdf
2015-12-22
13
22
10.22059/jesphys.2015.57223
Focal mechanism
ISOLA
Moment tensor inversion
Stress inversion
Strike-slip faulting
Nina
Ataei
nina.ataei@ut.ac.ir
1
M.Sc. Student, Department of Earth Physics, Institute of Geophysics, University of Tehran, Ira
AUTHOR
Mahdi
Rezapour
rezapour@ut.ac.ir
2
Associate Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
LEAD_AUTHOR
Berberian, M., Jackson, J., Fielding, E., Parsons, B., Priestley, K., Qorashi, M., Talebian, M., Walker, R., Wright, T. and Baker, C., 2001, The 1999 March 14 Fandoqa earthquake (Mw= 6.6) in Kerman province, southeast Iran: re-rupture of the 1981Sirch earthquake fault, triggering of slip on adjacent thrusts and the active tectonics of the Gowk fault zone, Geophys. J. Int., 146, 371-398.
1
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3
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5
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18
ORIGINAL_ARTICLE
Attenuation of Fourier spectra for 2012 Ahar–Varzaghan earthquakes, Northwestern Iran
In this research, we have used 102 strong motion recordings from 2012 Ahar-Varzaghan earthquakes (Mw=6.5 and Mw=6.3) to study the form of attenuation of shear wave Fourier amplitude spectra of those two events. The analysis is carried out in a broad-band frequency range from 0.1 to 20 Hz. A bilinear shape for geometrical spreading is assumed based on nonparametric regression of the data. The hinge point of the bilinear shape is around 60 km away from the earthquake source; the geometric spreading forms for the first and second segments are R-0.9 and R-0.5, respectively. The results of this study show that there is considerable dependency of the rate of geometrical spreading on frequency. If only frequencies above 1 Hz are considered, the first segment of geometrical spreading will have a slope steeper than R-1. In contract, for lower frequencies it has a gentle slope. The associated quality factor for the assumed shape of geometrical spreading (appropriate for frequencies logarithmically spaced between 0.1 to 20 Hz) is Q(f)=148 f 0.62. The estimated Q(f) in this study agrees well with the other estimated shear wave quality factors in the region; however, if the whole attenuation model (consisted of geometrical spreading and quality factor) is considered, there will be conspicuous differences between different models.
https://jesphys.ut.ac.ir/article_56029_a5b68556855166cb70a4ddb97739ef52.pdf
2015-12-22
23
38
10.22059/jesphys.2015.56029
Ahar-Varzaghan earthquakes
Attenuation
Fourier spectra
Geometrical spreading
Northwestern Iran
quality factor
Meghdad
Samaei
meghdad.samaei@gmail.com
1
Postdoctoral Researcher, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan
LEAD_AUTHOR
Masakatsu
Miyajima
miyajima@t.kanazawa-u.ac.jp
2
Professor, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan
AUTHOR
Nobuoto
Nojima
nojima@gifu-u.ac.jp
3
Professor, Department of Civil Engineering, Gifu University, Gifu, Japan
AUTHOR
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Attenuation of Fourier spectra for 2012 Ahar–Varzaghan… 37
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ORIGINAL_ARTICLE
Development of a regional attenuation relationship for Alborz, Iran
New attenuation relationships for rock and soil in Alborz, have been developed in this study. When the quantity of usable ground-motion data is inadequate in the magnitude and distance ranges, development of an empirical prediction equation is deficient. Due to lack of data, the two well-known simulation techniques, point source and finite-fault models have been used to generate more than ten thousands of strong motions as input data. The stochastic finite-fault modeling that can be used to predict regional groundmotion for large faults has been developed based on subdividing the fault surface into smaller subsources, as stochastic point sources. The model incorporates the seismological information obtained from recorded data of northern Iran to provide new information on source and path effects. In this study, the uncertainty due to inherent variability in earthquake source, path, and site effects has been considered. The results include the attenuation relationships that are validated by statistical analysis to compare the estimated ground motion with those of recorded data at the observed stations in Alborz region.
https://jesphys.ut.ac.ir/article_55909_f1e62589761451c8055e3b2214a36d9a.pdf
2015-12-22
39
50
10.22059/jesphys.2015.55909
Attenuation relationship
Alborz
Stochastic simulation
uncertainty
Azad
Yazdani
a.yazdani@uok.ac.ir
1
Associate Professor, Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran
LEAD_AUTHOR
Milad
Kowsari
miladkowsari@gmail.com
2
Graduated Student, Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran
AUTHOR
Sargol
Amani
sa.amani1989@yahoo.com
3
Graduated Student, Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran
AUTHOR
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56
ORIGINAL_ARTICLE
A comparison between the Kazerun (Iran) and the North Anatolian (Turkey) fault systems in fault interaction and seismicity migration based on the spatiotemporal analysis of earthquakes
The Kazerun Fault System (KFS) is a right-lateral strike slip fault system in the middle part of the Zagros seismogenic zone in Iran. Historical and instrumental earthquake data catalogs of this fault system show good evidence of fault interactions and seismic migrations. This study provides evidence for the migration of seismicity in the middle part of the Zagros region along the segments of the KFS, as well as, among the Kazerun fault segments. North Anatolian Fault System (NAFS) is similar to the Kazerun Fault System (KFS) and there are also interactions among the segments of the NAFS. In this paper, we have described the fault interactions and seismic migrations in the KFS and NAFS based on the spatiotemporal analysis of the earthquake data of these two regions in a period of 5 years (from 2005 to 2010). The obtained results indicate that these migrations mainly occur along the trend of these fault systems. Additionally, we found a good agreement between these seismicity patterns and the overall ongoing plate tectonic movements in these parts of the World.
https://jesphys.ut.ac.ir/article_55912_e1408df849e4f6a3340eeb5548b345e7.pdf
2015-12-22
51
67
10.22059/jesphys.2015.55912
Fault interaction
Kazerun fault system
North Anatolian fault system
Spatiotemporal analysis
seismicity
Azra
Hasanlou
azrahasanlou@gmail.com
1
M.Sc. Expert, Geological Survey of Iran, Tehran, Iran
LEAD_AUTHOR
Sayed Naser
Hashemi
hashemi@du.ac.ir
2
Assistant Professor, School of Earth Sciences, Damghan University, Damghan, Iran
AUTHOR
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2
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Res, 156, 506-526.
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79
ORIGINAL_ARTICLE
Relationship between head wave amplitudes and seismic refraction velocities to detect lateral variation in the refractor
Refractor ambiguities are big problem in seismic refraction method especially in seismic engineering. There can be hidden subsurface geological phenomena such as hidden faults and shear zones which are not simply predicted by the travel-time graph or some geophysical methods. Head wave amplitudes are used to show the resolution of refractor ambiguities and the existence of anisotropy in complex geological area. Wave amplitude is proportional to the square root of energy density; it decays as 1/r. In practice, velocity usually increases with depth, and causes further divergence of the wave front and a more rapid decay in amplitudes with distance. Amplitudes measured from first peak to first trough and corrected for geometric spreading, can be demonstrated some subsurface information such as anisotropy. Meanwhile, amplitudes are not commonly study by researchers in seismic refraction studies, because of being the very large geometric spreading components due to variations related to wave speeds in the undulated refractor. The variations in amplitudes are described with the transmission coefficient of the Zoeppritz equations. This variation in velocity and density produces head wave amplitude and head coefficient changes in refractor, even with refractors exhibiting large variations in depth and wave speeds. The head coefficient can be approximately calculated by the ratio of the specific acoustic impedance in the overburden layer in the refractor. This study shows that there is a relationship between the amplitude and the seismic velocity which the lower the contrast in seismic velocity and/or density, the higher the amplitude and vice versa.
https://jesphys.ut.ac.ir/article_53699_c96ede9b6cb552d99fd507957c9a14b1.pdf
2015-12-22
69
76
10.22059/jesphys.2015.53699
Head wave amplitudes
Seismic velocity
Acoustic impedance
seismic refraction
Ramin
Nikrouz
r.nikrouz@urmia.ac.ir
1
Assistant Professor, Geology Group, Urmia University, Iran
LEAD_AUTHOR
Brown, A. R., 1987, The value of seismic amplitude, The Leading Edge, October 1987, 30-33.
1
Brown, A. R., 1996, Interpretation of three-dimensional seismic data, AAPG Memoir, 42.
2
Cerveny, V. and Ravindra, R., 1971, Theory of seismic head waves, University of Toronto Press.
3
Gebrande, H. and Miller, H., 1985, Refraction seismology, In: Bender, F. (Ed), Applied Geosciences, methods of applied geophysics and mathematical procedures in geosciences, F. Enke publishing house, Stuttgart.
4
Heelan, P. A., 1953, On the theory of head waves, Geophysics, 18, 871-893.
5
Nikrouz, R., 2005, Three-dimensional (3D) three-component (3D) shallow seismic refraction surveys across a shear zone associated with dryland salinity at the spicers creek catchment, PhD thesis, School of Geology, NSW, Sydney, Australia.
6
Nikrouz, R., 2006, Near-surface corrections with the GRM, 17th International Geophysical Congress & Exhibition by CGET, 14-17 Nov., Ankara-Istanbul.
7
Nikrouz, R. and Palmer, D., 2004, 3D 3C seismic refraction imaging of shear zone sources of dryland salinity, 17th Geophysical Conference and Exhibition, 15-19 August, Sydney, Australia.
8
O’Brien, P. N. S., 1967, The use of amplitudes in seismic refraction survey, in: Musgrave, A. W. (Ed), Seismic refraction prospecting, Society of Exploration Geophysicists, Tulsa.
9
Palmer, D., 1986, Refraction seismics, the lateral resolution of structure and seismic velocity, Geophysical Press.
10
Palmer, D., 2001a, Resolving refractor ambiguities with amplitudes, Geophysics, 66, 1590-1593.
11
Palmer, D., 2001b, Digital processing of shallow seismic refraction data with the refraction convolution section, PhD thesis, School of geology, NSW, Sydney, Australia.
12
Palmer, D., 2001c, Imaging refractors with the convolution section, Geophysics, 66, 1582-1589.
13
Palmer, D., 2003a, Application of amplitudes in shallow seismic refraction inversion, ASEG 19th Geophysical Conferences and Exhibition, Adelide.
14
Palmer, D., 2003b, Processing and interpreting shallow seismic refraction data with the GRM and the CRM, unpublished: university of New South Wales, Sydney, Australia.
15
Palmer, D., 2006, Refraction travel time and amplitude corrections for very near-surface in homogeneities, Geophysical Prospecting, 54, 589-604.
16
Palmer, D., Nikrouz, R. and Spyrou, A., 2005, Statics corrections for shallow seismic refraction data, Exploration Geophysics, 36, 7-17.
17
Werth, G. A., 1967, Method for calculating the amplitude of the refraction arrival, in: Musgrave, A. W. (Ed), seismic refraction prospecting, Society of Exploration Geophysics, 119-137.
18
ORIGINAL_ARTICLE
Application of 2D inversion of magnetotelluric in exploration of hydrocarbon in south west of Iran
Since hydrocarbon sources have an important role in development of industry and technology, exploration of them has been lionized by human. The seismic reflection method is one of the most applicable investigative methods to identify the hydrocarbon reservoirs, but in some cases this method does not work well because of geology conditions and wave attenuation in depth. Thus, some exploration methods such as magnetotelluric can help us reach better results and lead to better interpretation of such reservoirs in compound with seismic methods. The Magnetotelluric (MT) method is suitable to map electrical resistivity in hydrocarbon explorations. This method has been widely used in exploration of conventional energy and also the renewable energy such as geothermal resources and a powerful tool to investigate different kinds of geological structures under the earth's surface. MT method usually focuses on the deeper geologic targets than the other EM methods. MT provides an excellent image of subsurface formations in the areas covered by high-velocity carbonate. The investigated area is located in southeastern part of the most prolific oil province of Iran, the Khuzestan in Dezful Embayment. Oil reservoirs of Iran have been contributed by Mesozoic and Cenozoic evaporated sediments. Multiple petroleum systems exist in the investigated area, since at least two proven source rocks exist within the area: The Kazhdumi and Pabdeh shale sediments. Tree main groups of reservoirs are recognized in the Khuzestan basin: the Khami Group, the Bangestan Group and the Asmari Formation. All the tree groups of reservoirs are recognized in investigated area with excellent fracture permeability and locally primary porosity. A formational interpretation of 2D inversion of MT data is used to demarcate hydrocarbon prospective formations underneath carbonated sediments of south west Iran. MT measurements are made in southwest Iran. The sites were distributed in two profiles of approximate SW-NE direction. Profiles are called P1 and P2, respectively. The MT experiment was carried out by deploying 63 sites with about 600 m spacing with 40 frequency values in seven decades and the period ranged 0.003-2000 (s). The dimensionality and the best geoelectrical strike estimation were carried out using tensor decomposition and phase tensor analysis. The ellipticity, phase tensor and skew angle are other measured parameters. NLCG inversion algorithm is used to inverse two MT data profiles. Both TE and TM modes with both MT polarizations were jointly inverted using the NLCG algorithm. The NLCG algorithm attempts to minimize an objective function that is the sum of the normalized data misfits and the smoothness of the model. The obtained MT sections show three anticlines underground. Seh Qanat anticline is the most important one in the investigated area. The lithological log of Seh Qanat Deep-1 (SQD-1) borehole is applied to interpret MT sections. This borehole has been drilled on Seh Qanat Anticline with total depth of 2876 meters. It could be detected a boundary of Asmari formation that is the primary shallow oil target in the investigated area. Other formations such as Sarvak, potentially are reservoir of hydrocarbon resources.
https://jesphys.ut.ac.ir/article_57224_d2ad658e31ae7c67f52c2313508dc71b.pdf
2015-12-22
77
88
10.22059/jesphys.2015.57224
Formational interpretation
Hydrocarbon resources
magnetotelluric
NLCG Algorithm
2D inversion
Mohammad Ali
Shahrabi
md.shahrabi@ut.ac.ir
1
M. Sc. in Geophysics, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
AUTHOR
Mohammad Kazem
Hafizi
hafizi@ut.ac.ir
2
Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
LEAD_AUTHOR
Hosein
Hashemi
hashemy@ut.ac.ir
3
Assistant Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
AUTHOR
Pejman
Shahsavari
pejmanshahsavari@gmail.com
4
M. Sc. in Geophysics, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
AUTHOR
Azeez, K. K. A., Kumar, T. S., Basava, S. T., Harinarayana, and Dayal, A. M., 2011, Hydrocarbon prospects across Narmadae Tapti rift in Deccan trap, central India: inferences from integrated interpretation of magnetotelluric and geochemical prospecting studies, J Marine and Petroleum Geology, 28, 1073-1082.
1
Cagniard, L., 1953, Basic theory of magnetotelluric method of geophysical prospecting, Geophysics, 18, 605-635.
2
Caldwell, G. T., Bibby, M. and Brown, C., 2004, The magnetotelluric phase tensor, Geo-phys. J. Int., 258, 457-469.
3
Constable, S. C., Parker, R. L. and Constable, C. G., 1987, Occam’s inversion: a practical algorithm for generating smooth models from EM sounding data, Geophysics, 52, 289-300.
4
Egbert, G. D. and Booker, J. R., 1986, Robust estimation of geomagnetic transfer functions, Geophys. J. R. Astr. Soc., 87, 173-194.
5
Favetto, A., Pomposiello, M. C., López de Luchi, M. and Booker, J., 2008, 2D Magnetotelluric interpretation of the crust electrical resistivity across the Pampean Terranee Río de la Plata suture, in Central Argentina, Tectonophysics, 459, 54-65.
6
Gamble, T. D., Goubau, W. M. and Clarke, J., 1979, Magnetotellurics with a remote magnetic reference, Geophysics, 44, 53-68.
7
Goldstein, N. E., 1988, Subregional and detailed exploration for geothermal hydrothermal resources, Geotherm. Sci. Tech., 1, 303-431.
8
Groom, R. W. and Bailey, R. C., 1989, Decomposition of magnetotelluric impedance tensors in the presence of local three-dimensional galvanic distortion, Journal of Geophysical Research 94, 1913-1925.
9
Lee, T. J., Song, Y. and Uchida, T., 2007, Three-dimensional magnetotelluric surveys for geothermal development in Pohang, Korea, Explor. Geophys., 60, 89-97.
10
Moteie, H., 2010, Petrolium geology of Iran, Arian Publications, pp. 978-964-91038-3-9.
11
Nichols, E. A., Morrison, H. F. and Clarke. J., 1988, Signals and noise in measurements of low-frequency geomagnetic fields, J. Geophys.Res., 93, 743-754.
12
Orange, A.S., 1989, Magnetotelluric exploration for hydrocarbons, Proc. IEEE, 77, 287-317.
13
Ogawa, Y. and Uchida, T., 1996, A two-dimensional magnetotelluric inversion assuming Gaussian static shift: Geophys. J. Int., 126, 69-76.
14
Rezaie, M. R., 2011, Petroleum geology of Iran, Alavi Publications, pp. 978-964-310-409-2.
15
Rodi, W., Mackie, R. L, 2001, Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion. Geophy sics, 66, 174-187.
16
Sahabi, F., 2012, Petroleum geology, University of Tehran, pp. 978-964-03-3790-5.
17
Sasaki, Y., 2004, Three-dimensional inversion of static-shifted magnetotelluric data, Earth Planets Space, 56, 239-248.
18
Smith, J. T. and Booker, J. R., 1991, Rapid
19
inversion of two- and three-dimensional magnetotelluric data, J. Geophys. Res., 96, 3905-3922.
20
Vozoff, K., 1991, The magnetotelluric method, in Electromagnetic Methods in Applied Geophysics, 2, 641-711. Wannamaker, P. E., Stodt, J. A. and Rijo, L., 1986, A stable finite element solution for two-dimensional magnetotelluric modelling, Geophys. J. Roy. Astr. Soc., 88, 277-296.
21
ORIGINAL_ARTICLE
Application of different inverse methods for combination of vS and vGPR data to estimate porosity and water saturation
Inverse problem is one of the most important problems in geophysics as model parameters can be estimated from the measured data directly using inverse techniques. In this paper, applying different inverse methods on integration of S-wave and GPR velocities are investigated for estimation of porosity and water saturation. A combination of linear and nonlinear inverse problems are solved. Linear least-squares and conjugate gradient are used as linear techniques, whereas grid search and Newton methods are selected as nonlinear ones. It is understood that vS depends on density and Lame Constant (shear modulus) and vGPR on dielectric constant. This combination seems to be logical. Shear modulus is related to porosity using Bruggeman’s rule. Density and dielectric constant is also related to porosity and water saturation. This implies that vS and vGPR are bivariate functions of porosity and water saturation, which are our unknown model parameters. The model parameters are estimated to minimize the cost functional ora system of the equations. In order to convert the nonlinear problem into the linear form, taking logarithm and changing variables were used. The problem was convex, which was inferred from the linear form, so there was just one local minimum as the global minimum of the problem. The grid search method shows that porosity and water saturation cannot be estimated by vGPR or vS uniquely. The results of the four methods were compared with each other and a good agreement was observed.
https://jesphys.ut.ac.ir/article_57225_e0f85c2be4519bea2495b29ae8d1dce5.pdf
2015-12-22
89
94
10.22059/jesphys.2015.57225
GPR wave
Inverse methods
Porosity
S wave
water saturation
Ramin
Varfinezhad
ramin.varfi@ut.ac.ir
1
M.Sc. Graduate, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
AUTHOR
Mohamd Kazem
Hafizi
hafizi@ut.ac.ir
2
Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
LEAD_AUTHOR
Hosein
Hashemi
hashemy@ut.ac.ir
3
Assistant Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
AUTHOR
Bachrach, R., 2006, Joint porosity and saturation using stochastic rock- physics modeling, Geophysics, 71, 53-63.
1
Birchak, J. R., Gardner, L. G., Hipp, J. W. and Victor, J. M., 1974, High electric constant microwave probes for sensing soil moisture, Proc. IEEE, 62(1), 93-98.
2
Dannowski, G. and Yaramanci, U., 1999, Estimation of water content and porosity using combined radar and geoelectrical measurements, European Journal of Environmental and Engineering Geophysics, 4, 71-85.
3
Boulanger, O. and Chouteau, M., 2001, Constraints in 3D gravity inversion, Geophysical Prospecting, 49, 265-280.
4
Aster, R. C., Borchers, B. and Clifford, H. T., 2005, Parameter estimation and inverse problems, Elsevier Academic Press.
5
Ghose, R. and Slob, E. C., 2006, Quantitative integration of seismic and GPR reflections to derive unique estimates for water saturation and porosity in subsoil, Geophysical Research Letters, 33, L05404.
6
Menke, W., 2012, Geophysical data analysis, discrete inverse theory, Elsevier Academic Press.
7
Sihvola, A., 1999, Electromagnetic mixing formulas and applications, 284 pp., Inst. of Electr. and Electron. Eng., New York.
8
Wang, J. R. and Schmugge, T. J., 1980, An empirical model for the complex dielectric permittivity of soils as a function of water content, IEEE Trans. Geosci. Remote Sens., 18, 288-295.
9
ORIGINAL_ARTICLE
Curie depth, Geothermal exploration, Iran, Kerman, Satellite magnetic field model.
In this paper an indirect method is presented to detect potential geothermal sites in Kerman province, southeast Iran. Geothermal heat flux is one of the main parameters to be investigated in geothermal exploration programs. However, few direct heat flux measurements are available for Iran. Given the proved relation between Curie depths and heat flux, magnetic data can be used to calculate the Curie depths in the areas where few or no direct heat flow measurements are available. The method presented here uses an iterative forward modeling approach to calculate the Curie depth in Kerman Province. It has used the satellite magnetic crustal field model of MF5 obtained from CHAMP mission. The equivalent source magnetic dipole method was used to estimate the magnetic crustal thickness from the observed induced field. The obtained Curie map reveals an area with very low Curie depth in the southeast Kerman. The area may be considered as a potential geothermal site. Geological evidence confirmed our findings for the probability of a geothermal site in the area.
https://jesphys.ut.ac.ir/article_57226_f34e1185a58f05859097b8939c93b018.pdf
2015-12-22
95
104
10.22059/jesphys.2015.57226
Curie depth
Geothermal exploration
Iran
Kerman
Satellite magnetic field model
Azadeh
Hojat
ahojat@uk.ac.ir
1
Assistant Professor, Department of Mining Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
LEAD_AUTHOR
Cathrine
Fox Maule
cam@dmi.dk
2
Danish Climate Centre, Danish Meteorological Institute, Denmark
AUTHOR
Kumar
Hemant Singh
hemantgfz@gmail.com
3
Department of Earth Sciences, Indian Institute of Technology, Bombay, India
AUTHOR
Artemieva, I. M., 2006, Global 1◦*1◦ thermal model TC1 for the continental lithosphere: Implications for lithosphere secular evolution, Tectonophysics, 416, 245-277.
1
Bhattacharyya, B. K. and Leu, L., 1977, Spectral analysis of gravity and magnetic anomalies due to rectangular prismatic bodies, Geophysics, 42, 41-50.
2
Blakely, R. J., 1988, Curie temperature isotherm analysis and tectonic implications of aeromagnetic data from Nevada, Journal of Geophysical Research, 93, 817-832.
3
Dolmaz, M. N., Ustaomer, T., Hisarli, Z. M. and Orbay, N., 2005, Curie point depth variations to infer thermal structure of the crust at the African-Eurasian convergence zone, SW Turkey, Earth Planets Space, 57, 373-383.
4
Dyment, J. and Arkani-Hamed, J., 1998a, Contribution of lithospheric remanent magnetization to satellite magnetic anomalies over the world's oceans, Journal of Geophysical Research, 103, 15423-15441.
5
Dyment, J. and Arkani-Hamed, J., 1998b, Equivalent source Magnetic dipoles revisited, Geophysical Research Letters, 25, 2003-2006.
6
Espinosa-Cardeña, J. M. and Campos-Enriquez, J. O., 2008, Curie point depth from spectral analysis of aeromagnetic data from Cerro Prieto geothermal area, Baja California, México, Journal of Volcanology and Geothermal Research, 176, 601-609.
7
Haggerty, S. E., 1978, Mineralogical
8
constraints on Curie isotherms in deep crustal magnetic anomalies, Geophysical Research Letters, 5, 105-108.
9
Hanano, M., 2000, Two different roles of fractures in geothermal development, Proceedings of the World Geothermal Congress 2000, Kyushu–Tohoku, Japan, 2597-2602.
10
Hemant, K., Maus, S. and Haak, V., 2005, Interpretation of CHAMP crustal field anomaly maps using Geographical Information System (GIS) technique, In: Reigber, C., Luhr, H., Schwintzer, P., Wickert, J., Earth observation with CHAMP; Results from three years in orbit, 249-254.
11
Langel, R. A. and Hinze, W. J., 1998, The magnetic field of the Earth’s Lithosphere –The satellite perspective, Cambridge University Press, ISBN: 0521473330.
12
Lesur, V. and Maus, S., 2006, A global lithospheric magnetic field model with reduced noise level in the Polar Regions, Geophysical Research Letters, 33, L13304, doi:10.1029/2006GL025826.
13
Maule, C. F., Purucker, M. E. and Olsen, N., 2009, Inferring magnetic crustal thickness and geothermal heat flux from crustal magnetic field models, Danish Climate Centre Report 09.
14
Maule, C. F., Purucker, M. E., Olsen, N. and Mosegaard, R., 2005, Heat flux anomalies in Antarctica revealed by satellite magnetic data, Science, 309, 464 - 467.
15
Maus, S., Lühr, H., Rother, M., Hemant, K., Balasis, G., Ritter, P. and Stolle, C., 2007, Fifth generation lithospheric magnetic field model from CHAMP satellite measurements, available at CHAMP homepage.
16
Maus, S., Rother, M., Hemant, K., Stolle, C., Lühr, H., Kuvshinov, A. and Olsen, N., 2006, Earth’s lithospheric magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements, Geophysical Journal International, 164, 319-330.
17
Maus, S., Rother, M., Holme, R., Lühr, H., Olsen, N. and Haak, V., 2002, First scalar magnetic anomaly map from CHAMP satellite data indicates weak lithospheric field, Geophysical Research Letters, 29(14), doi: 10.1029/2001GL013, 685.
18
Mayhew, M. A., 1982, Application of satellite magnetic anomaly data to Curie isotherm mapping, Journal of Geophysical Research, 87, 4846-4854.
19
Mayhew, M. A., 1985, Curie isotherm surfaces inferred from high-altitude magnetic anomaly data, Journal of Geophysical Research, 90, 2647-2654.
20
Mayhew, M. A., Johnson, B. D. and Wasilewski, P., 1985, A review of problems and progress in studies of satellite magnetic anomalies, Journal of Geophysical Research, 90, 2511-2522.
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Nataf, H. C. and Ricard, Y., 1996, 3SMAC: an a priori tomographic model of the upper mantle based on geophysical modeling, Physics of the Earth and Planetary Interiors, 95, 101-122.
22
National Geoscience Database of Iran (NGDIR)
23
Noorollahi, Y., Itoi, R., Fujii, H. and Tanaka, T., 2007, GIS model for geothermal resource exploration in Akita and Iwate prefectures, northern Japan, Computers and Geosciences, 33, 1008-1021.
24
Okubo, Y., Graf, R., Hansen, R., Ogawa, K. and Tsu, H., 1985, Curie point depths of the island of Kyushu and surrounding areas, Japan, Geophysics, 53, 481-494.
25
Pollack, H. N., Hurter, S. J. and Johnson, J. R., 1991, A new global heat flow compilation, Department of Geological Sciences, The University of Michigan.
26
Purucker, M., Langlais, B., Olsen, N., Hulot, G. and Mandea, M., 2002, The southern edge of Cratonic North America: Evidence from new satellite magnetometer observations, Geophysical Research Letters, 29, doi: 10.1029/2001GL013645, Art. No. 1342.
27
Rajaram, M., Anand, S. P., Hemant, K. and Purucker, M. E., 2009, Curie isotherm map of Indian subcontinent from satellite and aeromagnetic data, Earth and Planetary Science Letters, 281, 147-158.
28
Salk, M., Pamukcu, O. and Kaftan, I., 2005, Determination of the Curie point depth and heat flow from Magsat data of western Anatolia, Journal of Balkan Geophysical Society, 8(4), 149-160.
29
Sarkar, R. K. and Saha, D. K., 2006, A note on the lithosphere thickness and heat flow density of the Indian Craton from MAGSAT data, Acta Geophysica, 54(2), 198-204.
30
Schlinger, C. M., 1985, Magnetization of
31
lower crust and interpretation of regional magnetic anomalies: Example from Lofoten and Vesteraalen, Norway, Journal of Geophysical Research, 90, 11484-11504.
32
Shuey, R. T., Schellinger, D. K., Tripp, A. C. and Alley, R., 1977, Curie depth determination from aeromagnetic spectra, Geophysical Journal of the Royal Astronomical Society, 50, 75-101.
33
Walker, R. and Jackson, J., 2002, Offset and evolution of the Gowk fault, S.E. Iran: a major intra-continental strike-slip system, Journal of Structural Geology, 24, 1677-1698.
34
Walker, R. T., 2006, A remote sensing study of active folding and faulting in southern Kerman province, S. E. Iran, Journal of Structural Geology, 28, 654-668.
35
Wasilewski, P. J. and Mayhew, M. A., 1992, The Moho as a magnetic boundary revisited, Geophysical Research Letters, 19, 2259-2262.
36
Wasilewski, P. J., Thomas, H. and Mayhew, M. A., 1979, The Moho as a magnetic boundary, Geophysical Research Letters, 6, 541-544.
37
Yousefi, H., Ehara, S. and Noorollahi, Y., 2006, Geothermal energy development in Iran, Annual meeting of Geothermal Research Society of Japan.
38
Yousefi, H., Noorollahi, Y., Ehara, S., Itoi, R., Yousefi, A., Fujimitsu, Y., Nishijima, J. and Sasaki, K., 2009, Developing the geothermal resources map of Iran, Geothermics, doi: 10.1016.
39
ORIGINAL_ARTICLE
Interpretation of gravity anomalies via terracing method of the profile curvature
One of the main goals of interpretation of gravity data is to detect location and edges of the anomalies. Edge detection of gravity anomalies is carried out by different methods. Terracing of the data is one of the approaches that help the interpreter to achieve appropriate results of edge detection. This goal becomes a complex task when the gravity anomalies have smooth borders due to gradual change of density contrast. In this article terracing of data has been inspected using the profile curvature method. The synthetic data are used to assess the accuracy and efficiency of the method in edge detection of gravity anomalies. The results of this research have been compared with the results of other methods such as first vertical derivation, analytic signal, tilt angle, horizontal gradient of tilt angle, and laplacian second derivative. Two real data set are also used to show the applicability of the method.
https://jesphys.ut.ac.ir/article_57227_fad1eb348a4d96aa8257b3fba45032fe.pdf
2015-12-22
105
113
10.22059/jesphys.2015.57227
Analytic signal
Laplacian operator
Local phase angle
Profile curvature
Mahnaz
Eskandari
eskandari.mahnaz@gmail.com
1
M.Sc. Graduated, Department of Geophysics, Islamic Azad University of Hamedan, Iran
AUTHOR
Vahid
Ebrahimzadeh Ardestani
ebrahimz@ut.ac.ir
2
Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran
LEAD_AUTHOR
Blakely, R. J., 1995, Potential theory in gravity and magnetic applications, Cambridge University Press, New York 326 pp.
1
Cooper, G. R. J. and Cowan, D. R. 2009, Terracing potential field data, Geophysical prospecting, 57, 1067-1071.
2
Cooper, G. R. J. and Cowan, D. R., 2006, Enhancing potential field data using filters based on the local phase: Comp. & Geoscience 32, 1585-1591.
3
Cooper, G. R. J. and Cowan, D. R., 2004, Filtering using variable order vertical derivatives, Computers & Geosciences, 30, 455-459.
4
Cordell, L. and McCafferty, A. E., 1989, A terracing operator for physical property mapping with Potential field data, Geophysics, 54, 621-634.
5
Kepr, B., 1969, Differential geometry. In: Rektorys, K. (Ed.), Survey of Applicable Mathematics, M.I.T. Press, Cambridge, 298-372.
6
Klingele, E. E., Marson, I. and Khahle, H. G., 1991, Automatic interpretation of gravity gradiometric data in two
7
dimensions: vertical gradient, Geophysical Prospecting, 39, 407-434.
8
Miller, H. G. and Singh, V., 1994, Potential field tilt-a new concept for location of potential field sources, J. Appl. Geophysics, 32, 213-217.
9
Mitasova, H. and Jarosalav, H., 1993, Interpolation by regularized spline with tension: II. Application to terrain modeling and surface geometry analysis, Mathematical Geology, 25, 657-669.
10
Nabighian, M. N., 1972, The analytical signal of 2D magnetic bodies with polygonal cross-section: Its properties and use for automated anomaly interpretation,Geophysics,37, 507-517.
11
Pilkington, M. and Keating, P., 2004, Contact mapping from gridded magnetic data- a comparison: Extended abstracts, ASEG17th Geophysical Conference and Exhibition.
12
Thomas, Jr., G. B., 1968, Calculus and analytic geometry: part two vectors and functions of several variables, Addison-Wesley Publishing, Reading, MA, USA. 784 pp.
13
Veruzco, B., Fairhead, J.D. and Green, C. M., 2004, New insights into magnetic derivatives for structural mapping: The Keading Edge, 23(2), 116-119.
14
ORIGINAL_ARTICLE
Depth estimation of gravity anomalies by S-transform of analytic signal
The S-transform has widely been used in the analysis of non-stationary time series. A simple method to obtain depth estimates of gravity field sources is introduced in this study. We have developed a new method based on the spectral characteristics of downward continuation to estimate depth of structures. This calculation procedure is based on replacement of the Fourier transform with the S-Transform in traditional downward formula. We expect the localized estimation of the depth of anomalies using the S-transform spectrum rather than FFT spectrum. Likewise in the wavelets which don’t have a direct relationship with wave numbers, the S-Transform corresponds to wave number instead of scale or pseudo wavenumber. This is the main advantage of using S-transform instead of wavelets. This advantage will lead to easier and more precise calculation of depth estimation. Synthetic examples indicate the usefulness of this method. The method was applied to field examples producing reasonable results comparable to some common methods such as wavelet-based source characterization and Euler deconvolution. It is possible to average the local spectra over the wavenumber axis that leads to the spectrum referenced to position axis. The depth of anomaly can be computed in any point of the profile by using localization of spectrum. Thereby, we can analyze distinguished traces of shallow and deep anomalies while the lateral effects are also considered.
https://jesphys.ut.ac.ir/article_57228_1ca471eb6b705a27b6d33e16c0c88fe4.pdf
2015-12-22
115
124
10.22059/jesphys.2015.57228
Analytic signal
depth estimation
Gravity data
S-Transform
Naeim
Mousavi
mousavi_naeim@ut.ac.ir
1
Ph.D. Candidate, Institute of Geophysics, University of Tehran, Tehran, Iran
AUTHOR
Vahid
Ebrahimzadeh Ardestani
ebrahimz@ut.ac.ir
2
Professor, Institute of Geophysics, University of Tehran, Tehran, Iran
LEAD_AUTHOR
Ardestani, E. V., 2010, Delineating and modeling an underground water conduit by scattered micro-gravity data and electrical resistivity sounding, Exploration Geophysics, 41, 210-218.
1
Blakely, R. J., 1995, Potential theory in gravity and magnetic applications, Cambridge University Press.
2
Cooper, G., 2004, The stable downward continuation of potential field data, Exploration Geophysics, 35, 260-265.
3
Cooper, G., 2006, Interpreting potential field data using continuous wavelet transforms of their horizontalderivatives, Computers & Geosciences, 32, 984-992.
4
Fedi, M. and Florio, G., 2011, Normalized downward continuation of potential fields within the quasi-harmonic region, Geophysical Prospecting, 59(6), 1087-1100;
5
Fedi, M., Primiceri, R., Quarta, T. and Villani, A. V., 2004, Joint application of continuous and discrete wavelet transform on gravity data to identify shallow and deep sources, Geophysical Journal International, 156, 7-21.
6
Garcia-Abdeslem, J., 1995, Inversion of the power spectrum from gravity anomalies of prismatic bodies, Geophysics, 60(6), 1698-1703.
7
Goodyear, B. G., Zhu, H., Brown, R. A. and Ross Mitchell, J., 2004, Removal of phase artifacts from fMRI data using a Stockwell transform filter improves brain activity detection, Magnetic Resonance in Medicine, 51, 16-21.
8
Gupta, O. P., 1988, A Fourier transform minimization technique for interpreting magnetic anomalies of some two-dimensional bodies, Canadian Journal of Exploration Geophysics, 24(2), 179-184.
9
Kern, M., 2003, An analysis of the combination and downward continuation of satellite, airborne and terrestrial gravity data, PhD thesis, the university of Calgary, Alberta, Canada.
10
Li, Y., Braitenberg, C. and Yang, Y., 2013, Interpretation of gravity data by the continuous wavelet transform: The case of the Chad lineament (North-Central Africa), Journal of Applied Geophysics, 90, 62-70.
11
Mansinha, L., Stockwell, R., G., Lowe, R., P., Eramian, M. and Schincariol, R., A., 1997, Local S-spectrum analysis of 1-D and 2-D data, Physics of the Earth and Planetary Interiors, 103, 329-336.
12
Mareshal, J. C., 1985, Inversion of potential field data in Fourier transform domain, Geophysics, 50(4), 685-691.
13
Maus, S. and Dimiri, V., 1996, Depth estimation from the scaling power spectrum of potential fields, Geophysical Journal International, 123, 113-120.
14
Odegard, O. and Berg, J. W., 1965, Gravity interpretation using the Fourier integral,Geophysics, xxx, 3, 424-438.
15
Pinnegar, C. R. and Mansinha, L., 2003, The S-transform with windows of arbitrary and varying shape, Geophysics, 68(1), 381-385.
16
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.
17
Nabighian, M. N., Ander, M. E., Grauch, V. J. S., Hansen, R. O., LaFehr, T. R., Li, Y., Pearson, W. C., Peirce, J. W., Phillips, J. D. and Ruder, M. E., 2005, Historical development of the gravity method in exploration: Geophysics, 70(6), 63ND-89ND.
18
Senapati, K. and Routray, A., 2011, Comparison of ICA and WT with S-transform based method for removal of ocular artifact from EEG signals, Journal of Biomedical Science and Engineering, 4, 341-351.
19
Stockwell, R. G., Mansinha, L. and Lowe, R. P., 1996, Localization of the complex spectrum: the S-transform, IEEE Transactions on Signal Processing, 44, 998-1001.
20
Vatankhah, S., Ardestani, E. V. and Renaut, R. A., 2013, Automatic estimation of the regularization parameter in 2-Dfocusing gravity inversion: an application to the Safo manganesemine in northwest of Iran, Journal of Geophysics and Engineering (in press).
21
ORIGINAL_ARTICLE
Lut 009, an H4 (S2, W4) ordinary chondrite meteorite from Lut Desert of Iran
Lut 009 meteorite was found during a trip to Lut Desert of Iran in March,2012, at 30°20.38' N, 59°09.04' E. Chemical compositions of equilibrated olivine (Fa19.3 ± 0.5) and orthopyroxene (Fs16.7 ± 0.6) show that the meteorite sample belongs to H group of ordinary chondrites, while the texture (chondrule petrography and plagioclase size) suggests a petrologic type of 4. The Lut 009 has been very weakly shock altered and has a shock stage of S2. Fe-Ni is completely weathered whereas less than 5 percent of troilite is still present. Therefore, the meteorite has a weathering grade of W4. Magnetic susceptibility is log χ =4.75 (χ in 10-9 m3/kg) and, thus, consistent with a W4 H ordinary chondrite. Here we report description of Lut 009 in the first extended study on a meteorite from Lut Desert. Along with this sample, in-progress investigations of other meteorites from the desert will open a window into the characteristics of meteorite concentrations in this region.
https://jesphys.ut.ac.ir/article_55100_608ce37509d391f059ca025823078c97.pdf
2015-12-22
125
130
10.22059/jesphys.2015.55100
Iran
Lut Desert
Meteorite
Ordinary chondrite
Hamed
Pourkhorsandi
pourkhorsandi@cerege.fr
1
Ph.D. Student, Aix-Marseille Université/CNRS/IRD, CEREGE UM34, Aix-en-Provence, France
LEAD_AUTHOR
Hassan
Mirnejad
hmirnejad@ut.ac.ir
2
Associate Professor, Department of Geology, Faculty of Sciences, University of Tehran, Iran
AUTHOR
Pierre
Rochette
rochette@cerege.fr
3
Professor, Aix-Marseille Université/CNRS/IRD, CEREGE UM34, Aix-en-Provence, France
AUTHOR
Jamshid
Hassanzadeh
jamshid@caltech.edu
4
Associate Researcher, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA
AUTHOR
Armstrong, J. T., 1988, Quantitative analysis of silicate and oxide minerals, comparison of Monte Carlo, ZAF, and U (qz) procedures, in: Newbury, D. E., (Ed.), Microbeam analysis. Proceedings of the 23rd Annual Conference of the Microbeam Analysis Society, San Francisco Press, San Francisco, 239-246.
1
Bland, P. A., Kelley, S. P., Berry, F. J., Cadogan, J. M. and Pillinger, C. T., 1997, Artificial weathering of the ordinary chondrite Allegan, Implications for the presence of Cl- as a structural component in akaganeite, Am. Mineral, 82, 1187-1197.
2
Bland, P. A., Zolensky, M. E., Benedix, G. K. and Sephton, M. A., 2006, Weathering of chondritic meteorites, in: Lauretta, D. S. and McSween, Jr., H. Y., (Eds.), Meteorites and the Early Solar System II, University of Arizona Press, Arizona, 853-867.
3
Buchwald, V. F. and Clarke, Jr., R. S., 1989, Corrosion of Fe-Ni alloys by Cl-containing akaganeite (β-FeOOH), the Antarctic meteorite case, Am, Mineral, 74, 657-667.
4
Ehsani, A. H. and Quiel, F., 2008, Remote sens, Environment, 112, 3284-3294.
5
Hutchison, R., 2004, Meteorites, a petrologic, chemical and isotopic synthesis, Cambridge University Press, Cambridge.
6
Koeberl, C. and Cassidy, W. A., 1991, Differences between Antarctic and non-Antarctic meteorites, An assessment, Geochim, Cosmochim, Ac(55), 3-18.
7
Lee, M. R. and Bland, P. A., 2004, Mechanisms of weathering of meteorites recovered from hot and cold deserts and the formation of phyllosilicates, Geochim, Cosmochim, Ac(68), 893-916.
8
Mahmoodi, F., 2002, The distribution of erg lands of Iran (in Persian), Forest and Range Protection Research Institute, Tehran.
9
Mildrexler, D. J., Zhao, M. and Running S. W., 2011, B. Am. Meteorol. Soc., 7, 855-860.
10
Pabot, H., 1967, Report to government of Iran, pasture development and range improvement through botanical and ecological studies, UNDP, Food and Agricultural Organization of the United Nations, Rome.
11
Pourkhorsandi, H. and Mirnejad, H., 2013, 44th Lunar and Planetary Science Conference, A1096.
12
Rochette, P., Gattacceca, J. and Lewandowski, M., 2012, Magnetic classification on meteorites and application to the Soltmany Fall. Meteorites, 2, 67-71.
13
Stöffler, D., Keil, K. and Scott E. R. D., 1991, Shock metamorphism of ordinary chondrites, Geochim, Cosmochim, Ac(55), 3845-3867.
14
Van Schmus, W. R. and Wood, J. A., 1967, A chemical-petrologic classification lot the chondritic meteorites, Geochim, Cosmochim, Ac(31), 747-765.
15
Wlotzka, F., 1993, A weathering scale for the ordinary chondrites, Meteoritics, 28, 460.
16
ORIGINAL_ARTICLE
Contributions of Atlantic Ocean to June-August Rainfall over Uganda and Western Kenya
This study investigates the contributions of Atlantic Ocean to June-August rainfall over Uganda and western Kenya (KU). The study has utilized the datasets including precipitation from the Global Precipitation Climatology Centre, North Atlantic Oscillation Index (NAOI), South Atlantic Ocean Dipole Index (SAODI), ERA-interim reanalysis, and the Atlantic Ocean Sea Surface Temperature (SST). Singular value decomposition (SVD), composite analysis and correlation analysis are used to achieve the objective of the study. Results show that the recent extreme rainfall events of June - August (JJA) season were experienced in 2007 (above normal) and 2009 (below normal). Further analysis reveals that there are significant coupled modes of variability; the first mode explains 32% whereas the second mode explains 16% of the total covariance. The first SVD mode captures the positive phase of the South Atlantic Ocean Dipole (SAOD) over Atlantic Ocean. This is associated with positive anomaly of rainfall in most parts of KU. The second SVD mode captures the negative phase of SAOD. The North Atlantic Ocean Index (NAOI) exhibits a significant positive correlation of coefficient ≥ 0.3 with the mean JJA rainfall anomaly over most parts of KU at 95% confidence level. The correlation between the mean JJA rainfall over most parts of KU and NAOI is higher compared to that with SAODI. The dominant moisture source in the region during JJA season is the Atlantic Ocean and the Congo rainforest. The findings from this study provide insight into the influence of Atlantic Ocean on the mean JJA rainfall over KU. The study recommends further research on the utilization of NAOI and SAODI as predictors of the JJA seasonal rainfall over the study area. The production of the JJA seasonal rainfall forecast in the region will enhance better utilization of water resources in the region
https://jesphys.ut.ac.ir/article_53833_b5ade5026270e03448bcb78200565e11.pdf
2015-12-22
131
140
10.22059/jesphys.2015.53833
Atlantic Ocean
JJA Rainfall
Kenya and Uganda
NAOI
SAODI
SVD
Bob Alex
Ogwang
bob_ogwang@yahoo.co.uk
1
Assistant Lecturer, Uganda National Meteorological Authority, Kampala, Uganda
LEAD_AUTHOR
Victor
Ongoma
victor.ongoma@gmail.com
2
Assistant Lecturer, Department of Meteorology, South Eastern Kenya University, Kitui, Kenya
AUTHOR
Wilson
Gitau
wi.gitau@uonbi.ac.ke
3
Professor, Department of Meteorology, University of Nairobi, Kenya
AUTHOR
Adler, R. F., Huffman, G. J., Chang, A., Ferraro R., Xie, P., Janowiak, J., Rudolf, B., Schneider, U., Curtis, S., Bolvin, D., Gruber, A., Susskind, J. and Arkin, P., 2003, The version 2 global precipitation climatology project (GPCP) monthly precipitation analysis (1979-Present), J. Hydrometeorol, 4, 1147-1167.
1
Anyah, R. O. and Semazzi, F. H. M., 2004, Simulation of the response of Lake Victoria basin climate to lake surface temperatures, Theor. Appl. Climatol., 79, 55-69.
2
Behera, S. K., Luo, J., Masson, S., Yamagata, T., Delecluse, P., Gualdiand, S. and Navarra, A., 2005, Paramount impact of the Indian Ocean dipole on the East African short rains, A CGCM Study, J. Climate, 18, 4514-4530.
3
Black, E., Slingo, J. and Sperber, K. R., 2003, An observational study of the relationship between excessively strong short rains in Coastal East Africa and Indian Ocean SST, Mon. Weather Rev., 131, 74-94.
4
Bowden, J. and Semazzi, F. H. M., 2007, Empirical analysis of intraseasonal climate variability over the Greater Horn of Africa, J. Climate, 20(23), 5715-5731.
5
Camberlin, P. and Philippon, N., 2002, The East African March - May rainy season: associated atmospheric dynamics and predictability over the 1968 - 97 period, J. Climate, 15, 1002-1019.
6
Camberlin, P., Janicot, S. and Poccard, I., 2001, Seasonality and atmospheric dynamics of the teleconnection between African rainfall and tropical sea-surface temperature, Atlantic vs. ENSO, Int. J. Climatol., 21, 973 -1005.
7
Chang, P. and Zebiak, S. E., 2003, El Nino and the Southern Oscillation: theory, Encyclopedia of Atmospheric Sciences, Vol. 2, J. R. Holton, J. A. Curry, and J. A. Pyle (Eds), Elsevier Science Ltd., London, UK.
8
Clark, C. O., Webster, P. J. and Cole, J. E., 2003, Interdecadal variability of the relationship between the Indian Ocean Zonal Mode and East African coastal rainfall anomalies, J. Climate, 16, 548-554. Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A. P., Monge-Sanz, B. M., Morcrette, J. J., Park, B. K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, 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, doi: 10.1002/qj.828.
9
Fischer, A. S., Terray, P., Guilyardi, E., Gualdi, S. and Delecluse, P., 2005, Two independent triggers for the Indian Ocean dipole /zonalmode in a coupled GCM, J. Climate, 18(17), 3428-3449.
10
Funk, C., Michaelsen, J. and Marshall, M., 2012, Mapping recent decadal climate variations in precipitation and temperature across Eastern Africa and the Sahel. In B. D. Wardlow, M.C. Anderson, and J. P. Verdin (eds.), Remote sensing of drought: innovative monitoring approaches, CRC Press, Boca Raton, FL, USA, 331-358
11
Hannachi, A., Jolliffe, I. T. and Stephenson, D. B., 2007, Empirical orthogonal functions and related techniques in atmospheric science, A review, Int. J. Climatol., 27(9), 1119-1152.
12
Harris, I., Jones, P. D., Osborn, T. J. and Lister, D. H., 2014, Updated high-resolution grids of monthly climatic observations - the CRU TS3.10 Dataset, Int. J. Climatol., 34(3), 623-642.
13
Hasternrath, S. and Polzin, D., 2004, Dynamics of the surface wind field over the equatorial Indian Ocean, Q. J. R. Meteorol. Soc., 130, 503-517,
14
Huffman, G. J., Bolvin, D. T. and Adler, R. F., 2011, GPCP version 2.2 combined precipitation data set, WDC-A, NCDC, Asheville, NC.
15
Indeje, M., Semazzi, F. H. M., Xie, L. and Ogallo, L. J., 2001, Mechanistic model simulations of the East African Climate using NCAR Regional Climate Model,
16
Influence of large scale orography on the Turkana Low-Level Jet, J. Climate, 14, 2710-2724.
17
IPCC, 2007, Climate change 2007, impacts, adaptation and vulnerability, in: Parry M. L., Canziani, O. F., Palutikof, J. P., vander, Linden, P. J., Hanson C. E. (eds) Contribution of working group II to the fourth assessment report of the intergovernmental panel on climate change, Cambridge University Press, Cambridge, pp. 976.
18
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19
Juneng, L. and Tangang, F. T., 2006, The covariability between anomalous northeast monsoon rainfall in Malaysia and sea surface temperature in Indian-Pacific sector: a singular value decomposition analysis approach, J. Phys. Sci., 17(2), 101-115.
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21
Madden, R. A. and Julian, P. R., 1994, Observations of the 40-50-day tropical oscillation-a review, Mon. Weather Rev., 122, 814-837.
22
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23
Marchant, R., Mumbi, C., Behera, S. and Yamagata, T., 2007, The Indian Ocean dipole – the unsung driver of climatic variability in East Africa, Afri. J. Ecol, 45(1), 4-16.
24
McHugh, M. J., 2004, Near-surface zonal flow and East African precipitation receipt during austral summer, J. Climate, 17, 4070-4079.
25
McHugh, M. J., 2006, Impact of south Pacific circulation variability on East African rainfall, Int. J. Climatol., 26, 505-521
26
McHugh, M. J. and Rogers, J. C., 2001, North Atlantic oscillation influence on precipitation variability around the Southeast African convergence zone, J. Climate, 14, 3631-3642.
27
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28
Mutai, C. C., and Ward, M. N., 2000, East African rainfall and the tropical circulation/convection on interseasonal to interannual timescales, J. Climate, 13, 3915-3939.
29
Mutai, C. C., Ward, M. N. and Colman, A. W., 1998, Towards the prediction of East African short rains based on sea surface temperature-atmosphere coupling, Int. J. Climatol., 17, 117-135.
30
Muthama, N. J., Masieyi, W. B., Okoola, R. E, Opere, A. O., Mukabana, J. R., Nyakwada, W., Aura, S., Chanzu, B. A. and Manene, M. M., 2012, Survey on the utilization of weather information and products for selected districts in Kenya, J. Meteorol. Rel. Sci., 6, 51-58.
31
Neng, S., Luwen, C. and Dongdong, X., 2002, A preliminary study on the global land annual precipitation associated with ENSO during 1948-2000, Adv. Atmos. Sci., 19, 993-1002.
32
Nicholson, S. E., 2008, A revised view of the West African monsoon: in the ITCZ really necessary? Presentation at the Conference on African Droughts, 2nd - 6thJune 2008, ICTP, Trieste, Italy.
33
Nikulin, G., Jones, C., Samuelsson, P., Giorgi, F., Asrar, G., Büchner, M., Cerezo-Mota, R., Christensen, O. B., Déqué, M., Fernandez, J., Hänsler, A., van Meijgaard, E., Sylla, M. B. and Sushama, L., 2012, Precipitation climatology in an ensemble of CORDEX-Africa regional climate Simulations, J. Climate, 25(10), 6057-6078. doi: 10.1175/JCLI-D-11-00375.1.
34
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ORIGINAL_ARTICLE
Investigation of the atmospheric circulation anomalies associated with extreme rainfall events over the Coastal West Africa
This study investigates the atmospheric circulation associated with extreme rainfall events over the coastal West Africa. The rainfall data of this study were obtained from the Global Precipitation Climatology Centre (GPCC), spanning from 1981 to 2010. The atmospheric datasets were also obtained from the ERA-Interim reanalysis. The study employed the Z-Index to categorize dry and wet years into seven distinct grades. The analyses focused on the summer monsoon rainfall season experienced in July to September (JAS). The extreme drought years were identified to be 1982 and 1983, while extreme wet years were pointed out to be 1999 and 2007. The area of study was dominated by anomalous westerly moisture transport, characterized by convergence at low level during wet years. The major source of moisture over the study area is Atlantic Ocean. Dry and wet years are characterized by positive and negative low-level geopotential height anomalies, respectively. Although the results of this study do not give a diagnosis of the reported rainfall variability, the information herein can be useful in the monitoring and update of seasonal forecasts. Accurate and reliable seasonal forecasting is beneficial in that it helps us minimize loss of lives and destruction of property.
https://jesphys.ut.ac.ir/article_55173_ddba18929909116d455fc3e9947d5d34.pdf
2015-12-22
141
149
10.22059/jesphys.2015.55173
Drought
Rainfall
West Africa
Variability
Kpaikpai
Batebana
2920413746@qq.com
1
Assistant Lecturer, College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China
AUTHOR
Bob
Alex Ogwang
bob_ogwang@yahoo.co.uk
2
Assistant Lecturer, Uganda National Meteorological Authority, Kampala, Uganda
AUTHOR
Zin
Mie Mie Sein
zinmiesein@yahoo.ca
3
Assistant Lecturer, Department of Meteorology and Hydrology, Myanmar
AUTHOR
Faustin
Katchele Ogou
203751483@qq.com
4
Assistant Lecturer, College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China
AUTHOR
Victor
Ongoma
victor.ongoma@gmail.com
5
Assistant Lecturer, Department of Meteorology, South Eastern Kenya University, Kitui, Kenya
LEAD_AUTHOR
Jean Paul
Ngarukiyimana
692271318@qq.com
6
Assistant Lecturer, College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China
AUTHOR
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