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The latest version of the state-of-the-art global land–atmosphere–ocean coupled climate forecast system of NCEP has shown considerable improvement in various aspects of the Indian summer monsoon. However, climatological mean dry bias over the Indian sub-continent is further increased as compared to the previous version. Here we have attempted to link this dry bias with climatological mean bias in the Eurasian winter/spring snow, which is one of the important predictors of the Indian summer monsoon rainfall (ISMR). Simulation of interannual variability of the Eurasian snow and its teleconnection with the ISMR are quite reasonable in the model. Using composite analysis it is shown that a positive snow anomaly, which is comparable to the systematic bias in the model, results into significant decrease in the summer monsoon rainfall over the central India and part of the Equatorial Indian Ocean. Decrease in the summer monsoon rainfall is also found to be linked with weaker northward propagation of intraseasonal oscillation (ISO). A barotropic stationary wave triggered by positive snow anomaly over west Eurasia weakens the upper level monsoon circulation, which in turn reduces the zonal wind shear and hence, weakens the northward propagation of summer monsoon ISOs. A sensitivity experiment by reducing snow fall over Eurasian region causes decrease in winter and spring snow depth, which in turn leads to decrease in Indian summer monsoon rainfall. Results from the sensitivity experiment corroborate with those of composite analysis based on long free run. This study suggests that further improvements in the snow parametrization schemes as well as Arctic sea ice are needed to reduce the Eurasian snow bias during winter/spring, which may reduce the dry bias over Indian sub-continent and hence predictability aspect of the model. 相似文献
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Neotectonic activity and parity in movements of Udaipur block of the Arvalli Craton and Indian Plate
HARSH BHU RITESH PUROHIT JOGA RAM PANKAJ SHARMA S R JAKHAR 《Journal of Earth System Science》2014,123(2):343-350
We report site motion of a permanent GPS site at Udaipur (udai), Rajasthan on the Udaipur block of Aravalli Craton. The GPS measurements of 2007–2011 suggest that the site moves at a rate of about 49 mm/year towards northeast. As the site motion is consistent with the predicted plate motion using the estimated euler pole of rotation for the Indian Plate, it implies that there is insignificant internal deformation/strain in the region. Such a deformation is consistent with very low seismic activity in the region. The epicenters of the infrequent low magnitude earthquakes are located on the Precambrian lineaments on the west of Udaipur Block, and on the NW–SE striking younger lineament in the south of the block. 相似文献
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CHANDRA K. SHARMA 《水文科学杂志》2013,58(3):327-333
Abstract In a mountainous country like Nepal, where precipitation from the monsoon (July) and the westerlies (January) occurs yearly, it is surprising to find partial drought conditions in space and time. This paper deals with the partial drought conditions and also the measures to combat them. 相似文献
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Northeast India region is one of the most seismically active areas in the world. Events data for the period 1897–2010, used
in this study has been largely compiled from global ISC, NEIC and GCMT databases. Historical seismicity catalogue of Gupta
et al (1986) and some events data from the bulletins of India Meteorological Department are also used. Orthogonal regression relations
for conversion of body and surface wave magnitudes to M
w,HRVD based on events data for the period 1978–2006 have been derived. An Orthogonal Standard Regression (OSR) relationship has
also been obtained for scaling of intensity estimates to M
w,NEIC using 126 global intensity events with intensity VI or greater during the period 1975–2010. 相似文献
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BHASHA M MANKAD RASHMI SHARMA SUJIT BASU P K PAL 《Journal of Earth System Science》2012,121(1):251-262
Altimeter data have been assimilated in an ocean general circulation model using the water property conserving scheme. Two
runs of the model have been conducted for the year 2004. In one of the runs, altimeter data have been assimilated sequentially,
while in another run, assimilation has been suppressed. Assimilation has been restricted to the tropical Indian Ocean. An
assessment of the strength of the scheme has been carried out by comparing the sea surface temperature (SST), simulated in
the two runs, with in situ derived as well as remotely sensed observations of the same quantity. It has been found that the assimilation exhibits a
significant positive impact on the simulation of SST. The subsurface effect of the assimilation could be judged by comparing
the model simulated depth of the 20°C isotherm (hereafter referred to as D20), as a proxy of the thermocline depth, with the
same quantity estimated from ARGO observations. In this case also, the impact is noteworthy. Effect on the dynamics has been
judged by comparison of simulated surface current with observed current at a moored buoy location, and finally the impact
on model sea level forecast in a free run after assimilation has been quantified in a representative example. 相似文献
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In Great Nicobar island ophiolite is restricted to the eastern coast of the island and occur as small isolated out crops in the terrain of Oligocene sediments. The ophiolitic rocks are represented by pillowed basalt, massive andesite and pyroclastic andesite. These volcanics represent dismembered members of the upper part of the ophiolite. Basalt is porphyritic in nature where phenocrysts of augite and plagioclase laths are set in a fine grained glassy to chloritic matrix. Andesites consists of phenocrysts of augite, altered feldspar and minor quartz which are set in ground mass of epidote-chlorite glass. Trace element and REE pattern suggests more fertile mantle source for andesite than that of basalt. Trace element characteristics indicate that the andesites and basalts were possibly derived from the same melt where andesite represents the more fractionated product.In Andaman Islands dismembered ophiolite with complete ophiolite stratigraphy are found only within the Eocene sediments. But the field disposition suggests that in Great Nicobar emplacement of the ophiolite continued even after the Oligocene sedimentation. The characters of the ophiolitic rocks in Great Nicobar island are similar to that of the Sunda outer arc ridge. 相似文献
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Abstract The distributed parameter model ANSWERS was used to predict runoff and soil loss from three agricultural watersheds in the arid zone of India. Model input parameters such as landform, drainage, soil and land use/land cover were derived from Landsat Thematic Mapper false colour composites and limited ground truth. The model predicted hydrographs and sediment graphs within acceptable limits. ANSWERS underpredicted the total soil loss by factors of 2.6 to 3.6. Reasons for these results are discussed. 相似文献
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