Variability of cloud liquid water and ice over South Asia from TMI estimates     

A. Bhattacharya  A. Chakraborty  V. Venugopal 《Climate Dynamics》2014,42(9-10):2411-2421

In this study, the Tropical Rainfall Measurement Mission based Microwave Imager estimates (2A12) have been used to compare and contrast the characteristics of cloud liquid water and ice over the Indian land region and the ocean surrounding it, during the premonsoon (May) and monsoon (June–September) seasons. Based on the spatial homogeneity of rainfall, we have selected five regions for our study (three over ocean, two over land). Comparison across three ocean regions suggests that the cloud liquid water (CLW) over the orographically influenced Arabian Sea (close to the Indian west coast) behaves differently from the CLW over a trapped ocean (Bay of Bengal) or an open ocean (equatorial Indian Ocean). Specifically, the Arabian Sea region shows higher liquid water for a lower range of rainfall, whereas the Bay of Bengal and the equatorial Indian Ocean show higher liquid water for a higher range of rainfall. Apart from geographic differences, we also documented seasonal differences by comparing CLW profiles between monsoon and premonsoon periods, as well as between early and peak phases of the monsoon. We find that the CLW during the lean periods of rainfall (May or June) is higher than during the peak and late monsoon season (July–September) for raining clouds. As active and break phases are important signatures of the monsoon progression, we also analysed the differences in CLW during various phases of the monsoon, namely, active, break, active-to-break and break-to-active transition phases. We find that the cloud liquid water content during the break-to-active transition phase is significantly higher than during the active-to-break transition phase over central India. We speculate that this could be attributed to higher amount of aerosol loading over this region during the break phase. We lend credence to this aerosol-CLW/rain association by comparing the central Indian CLW with that over southeast Asia (where the aerosol loading is significantly smaller) and find that in the latter region, there are no significant differences in CLW during the different phases of the monsoon. While our hypothesis needs to be further investigated with numerical models, the results presented in this study can potentially serve as a good benchmark in evaluating the performance of cloud resolving models over the Indian region.  相似文献   

A high strain‐rate constitutive model for sand and its application in finite‐element analysis of tunnels subjected to blast     

William Higgins  Tanusree Chakraborty  Dipanjan Basu 《国际地质力学数值与分析法杂志》2013,37(15):2590-2610

The paper presents a constitutive model for simulating the high strain‐rate behavior of sands. Based on the concepts of critical‐state soil mechanics, the bounding surface plasticity theory and the overstress theory of viscoplasticity, the constitutive model simulates the high strain‐rate behavior of sands under uniaxial, triaxial and multi‐axial loading conditions. The model parameters are determined for Ottawa and Fontainebleau sands, and the performance of the model under extreme transient loading conditions is demonstrated through simulations of split Hopkinson pressure bar tests up to a strain rate of 2000/s. The constitutive model is implemented in a finite‐element analysis software Abaqus to analyze underground tunnels in sandy soil subjected to internal blast loads. Parametric studies are conducted to examine the effect of relative density and type of sand and of the depth of tunnel on the variation of stresses and deformations in the soil adjacent to the tunnels. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

String cosmology with Brans-Dicke theory     

Subenoy Chakraborty  Alakananda Gupta 《Astrophysics and Space Science》1996,239(1):65-70

In this paper string cosmology has been developed in the presence of Brans-Dicke scalar field coupled to Einstein gravity. Solutions are obtained for both geometric andp-string models and physical situations are discussed.  相似文献   

Quasi-spherical collapse with cosmological constant     

Ujjal Debnath  Soma Nath  Subenoy Chakraborty 《Monthly notices of the Royal Astronomical Society》2006,369(4):1961-1964

The junction conditions between static and non-static space–times are studied for analysing gravitational collapse in the presence of a cosmological constant. We have discussed about the apparent horizon and their physical significance. We also show the effect of cosmological constant in the collapse and it has been shown that cosmological constant slows down the collapse of matter.  相似文献   

A Study of an Inhomogeneous Bianchi-I Model in Lyra Geometry     

Farook Rahaman  Subenoy Chakraborty  Jayanta Kr. Bera 《Astrophysics and Space Science》2002,281(3):595-600

The inhomogeneous Bianchi-I model based on Lyra's geometry has been studied in the cosmological theory in presence of a massless inhomogeneous scalar field whose potential has a flat part. The field equations are solved using separation of variables and it is shown that one of the time part of the field equations are solvable for any arbitrary other cosmic scale function. Solutions for a particular form of cosmic scale (time part) is presented. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Estimation of Raft Settlement Based on Linear Elastic Finite Element Analysis     

Bhartiya  Priyanka  Chakraborty  Tanusree  Basu  Dipanjan 《Geotechnical and Geological Engineering》2022,40(6):2907-2919

Geotechnical and Geological Engineering - A detailed parametric study based on linear-elastic three-dimensional finite element (FE) analysis with proper raft–soil interaction is performed for...  相似文献   

Hazardous air pollutants and flooding: a comparative interurban study of environmental injustice   总被引：1，自引：0，他引：1  

Sara Grineski  Timothy W. Collins  Jayajit Chakraborty  Marilyn Montgomery 《GeoJournal》2015,80(1):145-158

  相似文献   

Structure and stability of rotating fluid disks around massive objects. I. Newtonian formulation     

D. K. Chakraborty  A. R. Prasanna 《Journal of Astrophysics and Astronomy》1981,2(4):421-437

In this paper we have presented a very general class of solutions for rotating fluid disks around massive objects (neglecting the self gravitation of the disk) with density as a function of the radial coordinate only and pressure being nonzero. Having considered a number of cases with different density and velocity distributions, we have analysed the stability of such disks under both radial and axisymmetric perturbations. For a perfect gas disk with γ= 5/3 the disk is stable with frequency (MG/r³)^1/2 for purely radial pulsation with expanding and contracting boundary. In the case of axisymmetric perturbation the critical γ_c for neutral stability is found to be much less than 4/3 indicating that such disks are mostly stable under such perturbations. On leave of absence from Government College, Jagdalpur 494005.  相似文献   

General relativistic analysis of structure and stability of charged fluid disks around compact objects     

A. R. Prasanna  D. K. Chakraborty 《Journal of Astrophysics and Astronomy》1981,2(1):1-27

In this paper we give a detailed general relativistic formulation of the study of structure and stability of charged fluid disks around compact objects like black holes neglecting the self-gravitation of the disk itself. Having presented the general equations for equilibrium as well as for perturbations we solve explicitly the cases of rigidly and differentially rotating thin disks, with constant charge density and zero pressure, confined to the equatorial plane of the black hole. By using normal mode analysis we have analysed the stability of such disks under purely radial perturbations and find that the disks are generally stable. On leave of absence from Government College, Jagadalpur 494005  相似文献   

Analysis of temporal sar and optical data for rice mapping     

Indrani?ChoudhuryEmail author  M.?Chakraborty 《Journal of the Indian Society of Remote Sensing》2004,32(4):373-385

This study investigates the potential of multi-temporal signature analysis of satellite imagery to map rice area in South 24 Paraganas district of West Bengal. Two optical data (IRS ID LISS III) and three RADARSAT SAR data of different dates were acquired during 2001. Multi-temporal SAR backscatter signatures of different landcovers were incorporated into knowledge based decision rules and kharif landcover map was generated. Based on the spectral variation in signature, the optical data acquired during rabi (January) and summer (March) season were classified using supervised maximum likelihood classifier. A co-incidence matrix was generated using logical approach for a combined “rabi-summer” and “kharif-rabi-summer” landcover mapping. The major landcovers obtained in South 24 Paraganas using remote sensing data are rice, water, aquaculture ponds, homestead, mangrove, and urban area. The classification accuracy of rice area was 98.2% using SAR data. However, while generating combined “kharif-rabi-summer” landcovers, the classification accuracy of rice area was improved from 81.6% (optical data) to 96.6% (combined SAR-Optical). The primary aim of the study is to achieve better accuracy in classifying rice area using the synergy between the two kinds of remotely sensed data.  相似文献