Influence of North Atlantic Oscillation on Indian Summer Monsoon Rainfall in Relation to Quasi-Binneal Oscillation     

R. Bhatla  A. K. Singh  B. Mandal  S. Ghosh  S. N. Pandey  Abhijit Sarkar 《Pure and Applied Geophysics》2016,173(8):2959-2970

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Copula entropy coupled with artificial neural network for rainfall–runoff simulation     

Lu Chen  Vijay P. Singh  Shenglian Guo  Jianzhong Zhou  Lei Ye 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1755-1767

The rainfall–runoff relationship is not only nonlinear and complex but also difficult to model. Artificial neural network (ANN), as a data-driven technique, has gained significant attention in recent years and has been shown to be an efficient alternative to traditional methods for hydrological modeling. However, for different input combinations, ANN models can yield different results. Therefore, input variables and ANN types need to be carefully considered, when using an ANN model for stream flow forecasting. This study proposes the copula-entropy (CE) theory to identify the inputs of an ANN model. The CE theory permits to calculate mutual information (MI) and partial MI directly which avoids calculating the marginal and joint probability distributions. Three different ANN models, namely multi-layer feed (MLF) forward networks, radial basis function networks and general regression neural network, were applied to predict stream flow of Jinsha River, China. Results showed that the inputs selected by the CE method were better than those by the traditional linear correlation analysis, and the MLF ANN model with the inputs selected by CE method obtained the best predicted results for the Jinsha River at Pingshan gauging station.  相似文献   

Fourier spectral- and duration models for the generation of response spectra adjustable to different source-, propagation-, and site conditions   总被引：3，自引：2，他引：1  

Sanjay Singh Bora  Frank Scherbaum  Nicolas Kuehn  Peter Stafford 《Bulletin of Earthquake Engineering》2014,12(1):467-493

One of the major challenges related with the current practice in seismic hazard studies is the adjustment of empirical ground motion prediction equations (GMPEs) to different seismological environments. We believe that the key to accommodating differences in regional seismological attributes of a ground motion model lies in the Fourier spectrum. In the present study, we attempt to explore a new approach for the development of response spectral GMPEs, which is fully consistent with linear system theory when it comes to adjustment issues. This approach consists of developing empirical prediction equations for Fourier spectra and for a particular duration estimate of ground motion which is tuned to optimize the fit between response spectra obtained through the random vibration theory framework and the classical way. The presented analysis for the development of GMPEs is performed on the recently compiled reference database for seismic ground motion in Europe (RESORCE-2012). Although, the main motivation for the presented approach is the adjustability and the use of the corresponding model to generate data driven host-to-target conversions, even as a standalone response spectral model it compares reasonably well with the GMPEs of Ambraseys et al. (Bull Earthq Eng 3:1–53, 2005), Akkar and Bommer (Seismol Res Lett 81(2):195–206, 2010) and Akkar and Cagnan (Bull Seismol Soc Am 100(6):2978–2995, 2010).  相似文献   

A ninth century earthquake-induced landslide and flood in the Kashmir Valley,and earthquake damage to Kashmir’s Medieval temples     

Roger Bilham  Bikram Singh Bali 《Bulletin of Earthquake Engineering》2014,12(1):79-109

An entry in the Tarikh-i-Hassan records that in 883 AD during the reign of King Avantivarman (855–883) an earthquake in Kashmir triggered a landslide that impounded the River Jhelum and flooded the Kashmir Valley. Kalhana’s Rajatarangini provides abundant details about how the ninth century engineer Suyya both cleared the natural dam, drained the valley and instituted numerous irrigation works. We identify the landslide(s) responsible for this Medieval flood and from twentieth century discharge statistics of the Jhelum calculate that it would have taken at least 2 years to flood the Kashmir Valley to near Anantnag. This presents a chronological difficulty, for the causal earthquake could not have occurred in the last 4 months of Avantivarman’s rule, and we conclude that it must have occurred much earlier, perhaps before the start of his reign. The flood occurred during a period of widespread temple building using massive uncemented limestone megablocks, capped by monolithic multi-ton roofs. Many of these magnificent temples, now in ruinous condition, are located close to the shores of the inferred Medieval flood level, suggesting that the transport of construction materials for these temples may have been ferried by barge from distant quarries. Historians and archaeologists have attributed the partial collapse of these temples to malicious damage by subsequent occupants of the valley, but the misalignment of blocks at lower levels within each edifice in recent earthquakes suggests that their lateral offsets are the result of jostling during prolonged shaking in historical earthquakes. From the serendipitous entrapment of datable materials beneath fallen blocks from Kashmir’s ninth century temples we can, in principle, identify the times of historical earthquakes. We chose the ruined Sugandhesa temple near Patan to test this hypothesis. Preliminary results indicate collapse in the tenth or eleventh century, and significant damage in 1885, with at least one intervening earthquake possibly in the seventieth century.  相似文献   

Comparative evaluation of performances of two versions of NCEP climate forecast system in predicting Indian summer monsoon rainfall   总被引：1，自引：0，他引：1  

Nachiketa Acharya  Makarand A. Kulkarni  Uma C. Mohanty  Ankita Singh 《Acta Geophysica》2014,62(1):199-219

The operational prediction of climatic variables in monthly-to-seasonal scales has been issued by National Centers for Environmental Prediction (NCEP) through Climate Forecast System model (CFSv1) since 2004. After incorporating significant changes, a new version of this model (CFSv2) was released in 2011. The present study is based on the comparative evaluation of performances of CFSv2 and CFSv1 for the southwest monsoon season (June-July-August-September, JJAS) over India with May initial condition during 1982–2009. It was observed that CFSv2 has improved over CFSv1 in simulating the observed monsoon rainfall climatology and inter annual variability. The movement of the cell of Walker circulation in years of excessive and deficient rainfall is better captured in CFSv2, as well. The observed teleconnection pattern between ISMR-sea surface temperature (SST) is also better captured in CFSv2. The overall results suggest that the changes incorporated in CFSv1 through the development of CFSv2 have resulted in an improved prediction of ISMR.21  相似文献   

Changing structure of the precipitation process during 1960–2005 in Xinjiang, China     

Qiang Zhang  Jianfeng Li  Vijay P. Singh  Chong-Yu Xu  Yungang Bai 《Theoretical and Applied Climatology》2012,110(1-2):229-244

Using daily precipitation data spanning 1960–2005 from 51 meteorological stations in Xinjiang province, China, spatial and temporal changes in consecutive maximum wet days in the year, summer, and winter were investigated. Fifteen precipitation extreme indices, which reflect the attributes of consecutive maximum wet days, were defined, and the modified Mann–Kendall test was applied to detect the tendencies, and changes in the indices were evaluated through linear regression with the F test. Results showed that: (1) two consecutive wet days occurred most frequently in the year and summer, and the fractional contributions and precipitation intensities decreased as the duration increased; in winter, one wet day had the maximum possibility, fractional contributions decreased and intensities increased as the duration increased. (2) The possibility of consecutive wet days which had short durations reduced, while those of long durations increased; annual fractional contributions of short durations decreased, while those of long durations increased; summer and winter fractional contribution of all durations decreased first and then increased; the intensities of all durations increased. (3) The wet tendency was identified in Xinjiang; the wet trend in Southern Xinjiang was more significant than Northern Xinjiang in summer, while in winter the wet tendency in Northern Xinjiang was more pronounced.  相似文献   

Above Ground Forest Phytomass Assessment in Southern Gujarat     

Prashant Patil  Sarnam Singh  V. K. Dadhwal 《Journal of the Indian Society of Remote Sensing》2012,40(1):37-46

Spectral modeling of above ground biomass (AGB) with field data collected in 48 field sites representing moist deciduous forest in Surat district is reported. Models were generated using LISS-III and MODIS data. The plot-wise field data was aggregated to MODIS pixel (250 m) using area weightages of forest/vegetation. The study reports that above ground phytomass varied from 6.13 t/ha to 389.166 t/ha while AGB phytomass estimated using area-weights for sites of 250×250 m, ranged from 5.534 t/ha to 134.082 t/ha. The contribution of bamboo in AGB has been found very high. The analysis indicated that the highest correlation between AGB phytomass and red band (R) of MODIS satellite data of October was (R²=0.7823) and R²=0.6998 with both NDVI of October data as well as NDVI_max. High correlation (R²=0.402) with IR band of February month was also found. The phytomass range obtained by using MODIS data varies from 0.147 t/ha to 182.16 t/ha. The mean biomass is 40.50 t/ha. Total biomass is 31.44 Mt. The mean Carbon density is 19.44 tC/ha in forest areas. The study is validation of region-wise spectral modeling approach that will be adopted for mapping vegetation carbon pool of the India under National Carbon Project of ISRO-Geosphere Biosphere Programme.  相似文献   

Influence of Atmospheric Water Vapour on IRS NIR Measurements for Detecting Vegetation Signal. Part I: A Simulation Study Using MODTRAN     

Mehul R. Pandya  Raghavendra Pratap Singh  Sushma Panigrahy  Jai Singh Parihar 《Journal of the Indian Society of Remote Sensing》2012,40(2):215-223

Quantitative remote sensing involving accurate estimation of vegetation properties relies greatly on the measurements of the near infrared (NIR) channel because of unique interaction property between light and leaf. It is generally assumed that the NIR measurements are made in the absence of atmospheric absorption. However, relatively weak water vapour absorption features still persist in the NIR channel, which has bearing on the quantitative estimates of the vegetation properties and long-term data series. This paper reports the results of a study that was carried out to infer the possible influence of the atmospheric water vapour (WV) on the NIR measurements (0.77–0.86 μm) of Indian Remote Sensing (IRS) satellite sensors through radiative transfer simulations using MODTRAN model. The study also suggests and evaluates the alternate band-positions for the NIR channel to improve the IRS NIR measurements. It was observed that the water absorption features present around 0.810 μm reduces the WV transmission of IRS NIR channel from 1 to 0.91 when atmospheric WV content increased from 0 to 6 g/cm² and thus hampered the NIR reflectance by 14% as compared to reference signal. A significant improvement of the order of 6.5 to 12% in the NIR reflectance and 4.2 to 7% in NDVI was observed, when IRS NIR channel was split into NIR1 (0.775–0.805 μm) and NIR2 (0.845–0.875 μm) channels by avoiding the WV absorption features. The companion paper in this issue (Pandya et al. 2011) will support results of this simulation study through the EO1-Hyperion data analysis.  相似文献   

A Methodology for Simulating Radionuclide Diffusion in Unsaturated Soils     

R. R. Rakesh  D. N. Singh  R. N. Nair 《Geotechnical and Geological Engineering》2009,27(1):13-21

In this paper, a methodology that can be employed to simulate radionuclide migration through unsaturated soils, under laboratory conditions, has been developed and reported. This was achieved with the help of a specially designed half-cell setup to study diffusion characteristics of inactive forms of Cs⁺, Sr⁺² and Co⁺² in two different types of soils, corresponding to their different compaction states. It has been noted that the apparent diffusion coefficient strongly depends on the volumetric water content of the soil. However, increase of the apparent diffusion coefficient for higher volumetric water contents is found to be much less as compared to the lower volumetric water contents.  相似文献   

<Emphasis Type="Bold">Rhodophycean algae from the Lower Cretaceous of the Cauvery Basin,South India</Emphasis> by P.K. Misra,S. Kishore,S.K. Singh and A.K. Jauhri. Jour. Geol. Soc. India,v.73, 2009, pp.325–334     

P. K. Misra  S. Kishore  S. K. Singh  A. K. Jauhri 《Journal of the Geological Society of India》2009,74(1):139-140

Discussion

Rhodophycean algae from the Lower Cretaceous of the Cauvery Basin, South India by P.K. Misra, S. Kishore, S.K. Singh and A.K. Jauhri. Jour. Geol. Soc. India, v.73, 2009, pp.325–334  相似文献