Tectonochemistry and p-t Conditions of Ramgarh and Almora Gneisses from Askot Klippe,Kumaun Lesser Himalaya     

Biraja P. DAS  Mallickarjun JOSHI  Ashutosh KUMAR 《《地质学报》英文版》2019,93(2):322-343

The chemical and petrological correlation of metamorphic nappes and klippes overlying the Proterozoic sedimentary units in the Kumaun Himalaya is still debated. The Ramgarh and Almora gneisses, not previously distinguished in the Askot Klippe, show distinct field, petrological and chemical signatures markedly similar to the tectonostratigraphic disposition of the Almora Nappe. A negative Eu anomaly in the Ramgarh granitic gneisses indicates lesser plagioclase fractionation while the Eu anomaly in the Almora pelitic gneisses is likely to have been controlled by feldspar crystallization in restites. During the anatexis at 776°C temperature and 6.6 kbar pressure, the melt moved slightly away to its crystallization sites. The Rb/Sr ratio ?0.54 and Nb ?10 ppm is consistent with the granodioritic composition. The negative Sr anomaly in the underlying Ramgarh granitic gneisses indicates a distinct mantle derived source/plagioclase fractionation with a notable correspondence to other late orogenic granites, particularly the basement Ulleri gneisses from the Nepal Himalaya. Ramgarh gneisses plot in the late-and post-COLG field. The Askot ensemble is likely to be the tectonometamorphically reworked basement, viz. the Ramgarh Group along with its metapelitic cover o f the Almora Group, together comprising southward thrust remnants of the leading edge of the Indian Plate that collided with Tibet during the Tertiary Himalayan orogeny.  相似文献   

Near shore waves,long-shore currents and sediment transport along micro-tidal beaches,central west coast of India     

Sajiv Philip CHEMPALAYIL  V Sanil KUMAR  G Udhaba DORA  Glejin JOHNSON 《国际泥沙研究》2014,29(3):402-413

Coastlines are undergoing constant geomorphologic changes with respect to the incident wave climate.Based on waves measured at 9 m water depth,simulation of near shore wave transformation is done using REFDIF-1numerical model and the near shore breaker parameters are estimated at two micro-tidal beaches along central west coast of India.Model results are validated with measured values.From the breaker parameters,long-shore current and long-shore sediment transport rates（LSTR） are computed by using semi-empirical equations.Estimated long-shore current and LSTR are showing dramatic variations with respect to seasons.Predominant direction of LSTR is observed towards north since the approach waves are from south-west direction during pre-monsoon and post monsoon.During monsoon season,waves are from west south-west and resulted in southerly transport.The estimated annual net and gross LSTR by Cambridge Environmental Research Consultants（CERC） at two locations are in the same order whereas LSTR estimated by Walton ＆ Bruno and Kamphuis equations are showing different estimations because of difference in surf-zone width and foreshore slope between the two locations.For micro-tidal beaches with length less than 6 km,Kamphuis equation is giving agreeable estimation of LSTR.Sensitivity analysis of LSTR estimate shows that coastal inclination is the prominent factor in determining LSTR than incident wave angle.  相似文献   

Benford’s Distribution in Extrasolar World: Do the Exoplanets Follow Benford’s Distribution?     

ABHISHEK SHUKLA  ANKIT KUMAR PANDEY  ANIRBAN PATHAK 《Journal of Astrophysics and Astronomy》2017,38(1):7

In many real life situations, it is observed that the first digits (i.e., 1,2,…,9) of a numerical data-set, which is expressed using decimal system, do not follow a uniform distribution. In fact, the probability of occurrence of these digits decreases in an almost exponential fashion starting from 30.1 % for 1 to 4.6 % for 9. Specifically, smaller numbers are favoured by nature in accordance with a logarithmic distribution law, which is referred to as Benford’s law. The existence and applicability of this empirical law have been extensively studied by physicists, accountants, computer scientists, mathematicians, statisticians, etc., and it has been observed that a large number of data-sets related to diverse problems follow this distribution. However, except two recent works related to astronomy, applicability of Benford’s law has not been tested for extrasolar objects. Motivated by this fact, this paper investigates the existence of Benford’s distribution in the extrasolar world using Kepler data for exoplanets. The quantitative investigations have revealed the presence of Benford’s distribution in various physical properties of these exoplanets. Further, some specific comments have been made on the possible generalizations of the obtained results, its potential applications in analysing the data-set of candidate exoplanets.  相似文献   

SLURP model and GIS for estimation of runoff in a part of Satluj catchment,India     

SANJAY K. JAIN  NARESH KUMAR  TANVEAR AHMAD  G. W. KITE 《水文科学杂志》2013,58(6):875-884

Abstract

The snow and rain in the Himalayas are the main sources of supply for the rivers in the Indo-Gangetic plains. Irrigation, hydropower generation, and water supply are very much dependent on the availability of water in the Himalaya rivers. Mathematical models serve as important aids for the estimation of water availability in rivers. In the present study the SLURP watershed model is applied to a rainfed area of the Satluj catchment located in the western Himalayas, India. The SLURP model developed at NHRI, Canada, is a distributed conceptual model which simulates the behaviour of a watershed by carrying out vertical water balances for each element of a matrix of landcovers and subareas of a watershed and then routing the resulting runoff between subareas. The ILWIS geographic information system was used to prepare the input data required for SLURP and land use data were obtained from the IRS satellite LISS II visible and near infrared sensors. The simulated flows at the Bhakhra Dam outlet of the Satluj catchment were computed and found to compare well with the observed flows.  相似文献   

Impact of additional surface observation network on short range weather forecast during summer monsoon 2008 over Indian subcontinent   总被引：1，自引：0，他引：1  

PRASHANT KUMAR  RANDHIR SINGH  P C JOSHI  P K PAL 《Journal of Earth System Science》2011,120(1):53-64

The three dimensional variational data assimilation scheme (3D-Var) is employed in the recently developed Weather Research and Forecasting (WRF) model. Assimilation experiments have been conducted to assess the impact of Indian Space Research Organisation’s (ISRO) Automatic Weather Stations (AWS) surface observations (temperature and moisture) on the short range forecast over the Indian region. In this study, two experiments, CNT (without AWS observations) and EXP (with AWS observations) were made for 24-h forecast starting daily at 0000 UTC during July 2008. The impact of assimilation of AWS surface observations were assessed in comparison to the CNT experiment. The spatial distribution of the improvement parameter for temperature, relative humidity and wind speed from one month assimilation experiments demonstrated that for 24-h forecast, AWS observations provide valuable information. Assimilation of AWS observed temperature and relative humidity improved the analysis as well as 24-h forecast. The rainfall prediction has been improved due to the assimilation of AWS data, with the largest improvement seen over the Western Ghat and eastern India.  相似文献   

Development of regional wheat VI-LAI models using Resourcesat-1 AWiFS data     

SASMITA CHAURASIA  R NIGAM  B K BHATTACHARYA  V N SRIDHAR  K MALLICK  S P VYAS  N K PATEL  J MUKHERJEE  CHANDER SHEKHAR  DHIRAJ KUMAR  K R P SINGH  G D BAIRAGI  N L PUROHIT  J S PARIHAR 《Journal of Earth System Science》2011,120(6):1113-1125

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Doppler SODAR observations of the temperature structure parameter during monsoon season over a tropical rural station,Gadanki     

M SHRAVAN KUMAR  V K ANANDAN  AMIT KESARKAR  P NARASIMHA REDDY 《Journal of Earth System Science》2011,120(1):65-72

Doppler SODAR (Sound Detection and Ranging) measurements over a tropical Indian station at National Atmospheric Research Laboratory (NARL), Gadanki (13.5°N, 79.2°E) during two consecutive monsoon seasons, 2007 and 2008, are investigated to study the influence of mechanically generated turbulence on temperature structure parameter (C_T²)_{\rm T}^{2}) in the convective boundary layer. Increase in the C_T²_{\rm T}^{2} is observed after the arrival of monsoon for both seasons. Contribution of vertical wind shear in horizontal wind component to C_T²_{\rm T}^{2} due to zonal winds is responsible for the increase observed in the temperature structure parameter which is inferred from the results obtained. C_T²_{\rm T}^{2} is found to be increased by an order of 2 in both the lower and upper altitudes, respectively. Magnitude of wind speed is reported to be doubled with the arrival of monsoon. It is also observed that, southwest monsoon wind modulates the day-to-day variations of wind pattern over this station during the onset phase of monsoon season. The lower variability observed at lower height is attributed to the complex topography surrounding this region.  相似文献   

Insights into the P–T evolution path of Tso Morari eclogites of the north-western Himalayas: Constraints on the geodynamic evolution of the region     

PREETI SINGH  ASHIMA SAIKIA  NARESH CHANDRA Pant  PRAMOD KUMAR VERMA 《Journal of Earth System Science》2013,122(3):677-698

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Existence of torsional surface waves in an earth’s crustal layer lying over a sandy mantle     

SUMIT KUMAR VISHWAKARMA  SHISHIR GUPTA 《Journal of Earth System Science》2013,122(5):1411-1421

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Lime muds and their genesis off-Northwestern India during the late Quaternary     

V PURNACHANDRA RAO  A ANIL KUMAR  S W A NAQVI  ALLAN R CHIVAS  B SEKAR  PRATIMA M KESSARKAR 《Journal of Earth System Science》2012,121(3):769-779

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