Recent changes in the spatio-temporal characteristics of monsoon intraseasonal oscillations     

Joseph  Susmitha  Sahai  A. K.  Shabu  Hindhiya  Chattopadhyay  R.  Kaur  Manpreet 《Theoretical and Applied Climatology》2022,147(1-2):251-264

Theoretical and Applied Climatology - Monsoon intraseasonal oscillations (MISOs) define a significant proportion of intraseasonal variability of the Indian summer monsoon. In the backdrop of...  相似文献   

Application of criteria and indicators in community based sustainable mangrove management in the Sunderbans,India     

Debajit Datta  P. Guha  R.N. Chattopadhyay 《Ocean & Coastal Management》2010,53(8):468-477

Management of mangroves in a sustainable ecological as well as economic way is a difficult proposition and needs multi-disciplinary intervention. This paper highlights the importance of criteria and indicators to evaluate the status of performance of communities in managing their mangroves sustainably. The framework developed on the basis of 6 principles, 12 criteria, 36 indicators and 47 verifiers had been applied for assessment of Eco-Development Committees of the Sunderbans, India. Results show the presence of a highly positive correlation between performance of the committees and condition of the mangrove environment. Level of implementation of legal and institutional management strategies to protect mangroves proves to be the essential pre-condition in achieving sustainability. The study further demonstrates the effectiveness of the developed framework in the context of community forestry since the methodology was designed to be simple and flexible so as to apply it in forest management unit level without any major difficulty.  相似文献   

North Indian heavy rainfall event during June 2013: diagnostics and extended range prediction     

Susmitha Joseph  A. K. Sahai  S. Sharmila  S. Abhilash  N. Borah  R. Chattopadhyay  P. A. Pillai  M. Rajeevan  Arun Kumar 《Climate Dynamics》2015,44(7-8):2049-2065

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Assessment of the spatio-temporal distribution of soil properties in East Kolkata wetland ecosystem (A Ramsar site: 1208)     

S Pal  S Manna  A Aich  B Chattopadhyay  S K Mukhopadhyay 《Journal of Earth System Science》2014,123(4):729-740

The present investigation was made to characterize spatial and temporal variations in soil properties and to evaluate possible differences that could be dependent on the tannery effluent discharges, municipal sewage discharges, vegetation cover, soil settlement rate, crop rotation, etc. Soil total organic matter (TOM), cations like, Sodium (Na), Ammonium (NH₄), Potassium (K), Calcium (Ca) and Magnesium (Mg) contents in the bank soils and bottom sediments were recorded from seven different characteristic sites in East Kolkata wetland ecosystem, a Ramsar site (Ramsar site No. 1208). The profile maps were constructed by geostatistical methods to describe the spatial distribution as well as temporal variations of all the factors to identify the influences of composite wastewaters. The work was initiated to identify causes and consequences of the waste dumping in the concerned region for the past hundred years and thereby to suggest necessary precautionary measures to prevent further loss of soil quality.  相似文献   

Recording and analyzing geospatially accurate structural data through ‘digital mapping’ technique: A case study from the Canisp Shear Zone,NW Scotland     

A. Chattopadhyay  R. E. Holdsworth  K. J. W. McCaffrey  R. W. Wilson 《Journal of the Geological Society of India》2010,75(1):43-59

Spatial accuracy of structural data is an important factor for construction of a properly scaled model of crustal structures. Digital Geological Mapping methods can add the required spatial accuracy to the data, and also can improve the versatility of the geological/structural map in many ways, which are difficult to achieve through conventional mapping techniques. The present paper describes the methodology of digital mapping and discusses its applicability in structural analyses in the Canisp Shear Zone (CSZ) — a reactivated continental basement structure in the Precambrian Lewisian Gneiss complex of NW Scottish Highland. The CSZ is reinterpreted as a major dextral transpressional shear zone developed during Laxfordian deformation. It overprinted an earlier Inverian shear zone fabric, and was later reactivated and/or overprinted by brittle shearing of different phases and different scales. Spatial analyses within the ArcGISTM environment has helped bring out the geological relationships between different types of structural data in the shear zone, highlighting the partitioning of deformation into zones of high and low strain. A kinematic interpretation based on the geospatial data analysis, combined with conventional stereographic projection technique, is presented.  相似文献   

Structural evolution of a gneiss dome in the axial zone of the proterozoic South Delhi Fold Belt in central Rajasthan     

Dhruba Mukhopadhyay  Nandini Chattopadhyay  Tapas Bhattacharyya 《Journal of the Geological Society of India》2010,75(1):18-31

The structural geometry of the Anasagar gneiss dome in the axial zone of the South Delhi Fold Belt is controlled by polyphase folding. It is classified as a thrust-related gneiss dome and not as a metamorphic core complex. Four phases of deformation have affected both the gneiss and the enveloping supracrustal rocks. D₂ and D₃ deformations probably represent early and late stages of a progressive deformation episode in a simple shear regime combined with compression. The contact between the gneiss and the supracrustal rocks is a dislocation plane (thrust) with top-to-east sense of movement which is consistent with the vergence of the D₂ folds. The thrust had a ramp-and-flat geometry at depth. At the present level of exposure it is a footwall flat (that is, parallel to the gneissosity in the footwall), but it truncates the bedding of the hanging wall at some places and is parallel at others. The thrusting was probably broadly coeval with the D₂ folds and the thrust plane is locally folded by D₂. D₂ and D₃ folds have similar style and orientation as the first and second phases respectively of major folds in the Delhi Supergroup of the South Delhi Fold Belt and these are mutually correlatable. It is suggested that D1 may be Pre-Delhi in age. Available geochronological data indicate that the emplacement of the Anasagar gneiss predated the formation of volcanic rocks in the Delhi Supergroup and also predated the main crust forming event in the fold belt. The Anasagar gneiss and its enveloping supracrustal rocks are probably older than the Delhi Supergroup.  相似文献   

Pilgrim dark energy in f(T,T G ) cosmology     

Surajit Chattopadhyay  Abdul Jawad  Davood Momeni  Ratbay Myrzakulov 《Astrophysics and Space Science》2014,353(1):279-292

We work on the reconstruction scenario of pilgrim dark energy (PDE) in f(T,T _G ). In PDE model it is assumed that a repulsive force that is accelerating the Universe is phantom type with (w _DE f(T,T _G ) models and correspondingly evaluate equation of state parameter for various choices of scale factor. Also, we assume polynomial form of f(T,T _G ) in terms of cosmic time and reconstruct H and w _DE in this manner. Through discussion, it is concluded that PDE shows aggressive phantom-like behavior for s=?2 in f(T,T _G ) gravity.  相似文献   

Generalized second law of thermodynamics in QCD ghost f(G) gravity     

Surajit Chattopadhyay 《Astrophysics and Space Science》2014,352(2):937-942

Considering power-law for of scale factor in a flat FRW universe we reported a reconstruction scheme for f(G) gravity based on QCD ghost dark energy. We reconstructed the effective equation of state parameter and observed “quintessence” behavior of the equation of state parameter. Furthermore, considering dynamical apparent horizon as the enveloping horizon of the universe we have observed that the generalized second law of thermodynamics is valid for this reconstructed f(G) gravity.  相似文献   

Prospects of hard X-ray polarimetry with Astrosat-CZTI     

T. Chattopadhyay  S. V. Vadawale  A. R. Rao  S. Sreekumar  D. Bhattacharya 《Experimental Astronomy》2014,37(3):555-577

Astrosat is the first Indian satellite mission dedicated for astronomical studies. It is planned for launch during 2014 and will have five instruments for multi-wavelength observations from optical to hard X-rays. Cadmium Zing Telluride Imager (CZTI) is one of the five instruments aiming for simultaneous X-ray spectroscopy and imaging in the energy range of 10 keV to 100 keV (along with all sky photometric capability unto 250 keV). It is based on pixilated CZT detector array with total geometric area of 1024 cm². It will have two-dimensional coded mask for medium resolution X-ray imaging. The CZT detector plane will be realized using CZT detector modules having integrated readout electronics. Each CZT detector module consists of 4 cm × 4 cm CZT with thickness of 5 mm which is further pixilated into 16 × 16 array of pixels. Thus each pixel has size of 2.5 mm × 2.5 mm and thickness of 5 mm. Such pixilated detector plane can in principle be used for hard X-ray polarization measurements based on the principle of Compton scattering by measuring azimuthal distribution of simultaneous events in two adjacent pixels. We have carried out detailed Geant4 simulations for estimating polarimetric capabilities of CZTI detector plane. The results indicate that events in the energy range of 100 keV to 250 keV, where the 5 mm thick CZT detector has significant detection efficiency, can be used for polarimetric studies. Our simulation results indicate the minimum detectable polarization (MDP) at the level of ～ 10% can be achieved for bright Crab like X-ray sources with exposure time of ～500 ks. We also carried out preliminary experiments to verify the results from our simulations. Here we present detailed method and results of our simulations as well as preliminary results from the experimental verification of polarimetric capabilities of CZT detector modules used in Astrosat CZTI.  相似文献   

An effective quintessence field with a power-law potential     

M. Khurshudyan  B. Pourhassan  R. Myrzakulov  S. Chattopadhyay 《Astrophysics and Space Science》2015,356(2):383-391

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