Ductile Shear Zones: From Micro‐ to Macro‐scales. Edited by: Soumyajit Mukherjee and Kieran. F. Mulchrone. Wiley‐Blackwell,Chichester, 2016. No. of pages: xii + 306. Price: US$175.00. ISBN: 978‐1‐118‐84496‐0 (hardcover).     

Dripta Dutta 《Geological Journal》2016,51(3):504-504

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Evaluating Environmental Sensitivity of Arid and Semiarid Regions in Northeastern Rajasthan,India          下载免费PDF全文

Srimoyee Dutta  Gargi Chaudhuri 《Geographical review》2015,105(4):441-461

Arid regions of Rajasthan in India are characterized by harsh environments, fragile ecosystems, and limited water resources and arable lands. Desertification is one of the major land‐degradation problems in these regions. Recent changes in the regional climatic regime and the low availability of water in this northwestern state of India, pose the threat of desertification in the agriculturally productive part of the state. This study aims to delineate the environmentally sensitive areas to desertification in the districts of Jhunjhunun and Sikar in Rajasthan, India. It uses geospatial data from various sources, and combines them to calculate an environmental sensitivity index (ESI), which will allow the quantification of the area's vulnerability to desertification. The study uses the analytical hierarchical process (AHP) to assign respective weights to individual factors for each index calculation. Land‐cover maps and socio‐economic data have been used to understand their relationship with ESI. Results showed that 13 percent and 45 percent of the study area are under highly sensitive and moderately sensitive zones, respectively. Mapping and monitoring of environmentally sensitive areas in such arid regions are critical to sustainable use and planning of natural resources namely water and land‐cover and are helpful in determining priority actions and their successful implementation.  相似文献   

Water Level Retrieval Using SARAL/AltiKa Observations in the Braided Brahmaputra River,Eastern India     

Amit Kumar Dubey  Praveen Gupta  Subashisa Dutta  Raghvendra Pratap Singh 《Marine Geodesy》2015,38(3):549-567

In this study, water level retrieval over the Brahmaputra river was done using different retracking algorithms for the 40 Hz waveform data of SARAL/AltiKa satellite. Water level was retrieved at 10 different locations of the river to evaluate the performance and accuracy of Ka band altimeter over the braided river system. Different retracking algorithms such as ice-1, ice-2, threshold, and beta parameter were used to retrieve water levels. A correlation and error analysis between the in-situ and satellite altimetry derived river levels was carried out for all the stations. Performance and accuracy analysis has established that water level can be retrieved with less than 40 cm root mean square error (RMSE) for most of the braided reaches of the river. The statistical analysis have found that Beta parameter algorithm has performed best in most of the cases amongst the different retracking algorithms used in this study. The water levels derived from 10 different locations were used to generate water surface elevation profiles for the monsoon and nonmonsoon periods. The water levels and the water surface profiles derived from satellite altimetry indicate the potential use of altimeters for the parameterization and calibration of river hydrological, hydrodynamic and sediment transport models.  相似文献   

Significant Results of Research on Gondwana Flora and Fauna     

P.M. Dutta  D.P. Das  G. Ahmed 《Gondwana Research》1999,2(4):661

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Thermonuclear X-ray burst of MXB 1658-298 with <Emphasis Type="Italic">NuSTAR</Emphasis>     

Rahul Sharma  Abdul Jaleel  Chetana Jain  Biswajit Paul  Anjan Dutta 《Journal of Astrophysics and Astronomy》2018,39(1):16

MXB 1658-298 is a transient Low-Mass X-ray Binary (LMXB), which shows eclipses, dips and bursts in its light curve. This source has undergone three active periods separated by long quiescent phases. The latest phase of enhanced X-ray emission was observed during 2015–2016. We have analysed broadband data from Swift/XRT and NuSTAR observations carried out in 2015. During NuSTAR observation, one thermonuclear X-ray burst took place. The X-ray emission during the burst was brighter by a factor of \(\sim 200\), compared to the pre-burst emission. This work focuses on the spectral analysis of MXB 1658-298 during the persistent and the burst phases using NuSTAR observation of 2015. We have also determined the temperature and radius evolution during the burst using the time-resolved spectroscopy. The burst phase shows mild Photospheric Radius Expansion (PRE).  相似文献   

VHF radar observations of gravity waves at a low latitude     

G. Dutta  B. Bapiraju  P. Balasubrahmanyam  H. Aleem Basha 《Annales Geophysicae》1999,17(8):1012-1019

Wind observations made at Gadanki (13.5°N) by using Indian MST Radar for few days in September, October, December 1995 and January, 1996 have been analyzed to study gravity wave activity in the troposphere and lower stratosphere. Horizontal wind variances have been computed for gravity waves of period (2–6) h from the power spectral density (PSD) spectrum. Exponential curves of the form e^Z/H have been fitted by least squares technique to these variance values to obtain height variations of the irregular winds upto the height of about 15 km, where Z is the height in kilometers. The value of H, the scale height, as determined from curve fitting is found to be less than the theoretical value of scale height of neutral atmosphere in this region, implying that the waves are gaining energy during their passage in the troposphere. In other words, it indicates that the sources of gravity waves are present in the troposphere. The energy densities of gravity wave fluctuations have been computed. Polynomial fits to the observed values show that wave energy density increases in the troposphere, its source region, and then decreases in the lower stratosphere.  相似文献   

Preserved lignin structures in early eocene Surat lignites,Cambay Basin,Western India     

Suryendu Dutta  Sanket Bhattacharya  Monalisa Mallick  Ashish Chandra Shukla  Ulrich Mann 《Journal of the Geological Society of India》2012,79(4):345-352

Lignite samples from Vastan and Tadkeshwar lignite mines, Cambay Basin have been analysed to elucidate lignin precursor using thermochemolysis-gas chromatography-mass spectrometry. The thermochemolysis products of lignites are characterized by monomethoxy-, dimethoxy-, and trimethoxybenzene derivatives originated from p-hydroxyphenyl, guaiacyl, and syringyl units of lignin polymer, respectively. The other compounds obtained in thermochemolysates of studied lignites are some resin derived C₁₅ sesquiterpenoids, with a series of fatty acid methyl esters and n-alkanes/alkenes. The methylated guaiacyl and syringyl derivatives originate from the cleavage of β-O-4 linkages and subsequent methylation of acidic hydroxyl groups of preserved lignin. Gymnosperm lignin is characterized mainly by guaiacyl derivatives whereas angiosperm lignin yields some syringyl-type compounds in addition to guaiacyl-type compounds. By analogy with the lignin structure of modern trees, the abundant occurrences of syringyl derivatives in the thermochemolysis products of Surat lignites clearly demonstrate that the palaeofloral community was dominated by angiosperms during the deposition of these lignites.  相似文献   

Role of convective and microphysical processes on the simulation of monsoon intraseasonal oscillation     

Dutta  Ushnanshu  Chaudhari  Hemantkumar S.  Hazra  Anupam  Pokhrel  Samir  Saha  Subodh Kumar  Veeranjaneyulu  Chinta 《Climate Dynamics》2020,55(9-10):2377-2403

Climate Dynamics - The study explores the role of ice-phase microphysics and convection for the better simulation of Indian summer monsoon rainfall (ISMR) and monsoon intraseasonal oscillation...  相似文献   

Assessment of Late Blight Induced Diseased Potato Crops: A Case Study for West Bengal District Using Temporal AWiFS and MODIS Data     

Sujay Dutta  Suresh K. Singh  Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2014,42(2):353-361

Remote sensing technology becomes an effective and inexpensive technique for detecting disease in vegetation. In this study, an attempt has been done to discriminate healthy and late blight affected crop using remote sensing based indices such as NDVI and LSWI. NDVI and LSWI spectral profiles between healthy and late blight affected crop shows large difference. Mean difference in reflectance between two acquired dates Jan. 10 and 29, 2009 crop clusters varied from 31.28 % in red band, 7.7 % in NIR band and 6.23 % in SWIR bands in healthy crops while in late blight affected crops it is ?15.5 % in red, 44.4 % in NIR and ?14.61 % in SWIR bands. Negative percentage differences in reflectance indicate reflectance increases from Jan. 10, 2009 to Jan. 29, 2009, while positive difference indicate decrease in reflectance between the two dates. Since potato is an irrigated crop, these differences in reflectance are attributed to prevalent disease at that time. It is found that severely affected areas are Bardhman, Arambag, Bishnupur, Ghatal and Hugli taluka with crop damage areas are 4036.66, 1138.68, 2025.23, 469.15, and 380.08 ha, respectively.  相似文献   

Measuring daytime CO2 fluxes from the inter-tidal mangrove soils of Indian Sundarbans     

Abhra Chanda  Anirban Akhand  Sudip Manna  Sachinandan Dutta  Indrani Das  Sugata Hazra  K. H. Rao  V. K. Dadhwal 《Environmental Earth Sciences》2014,72(2):417-427

The aim of this research was to measure the rate of carbon dioxide (CO₂) exchange between the soil and atmosphere in the inter-tidal forest floor of the Indian Sundarbans mangrove ecosystem and to study its response with soil temperature and soil water content. Soil CO₂ effluxes were monitored every month at two stations (between April, 2011 and March, 2012); one situated at the land–ocean boundary of the Bay of Bengal (outer part of the mangrove forest) and the other lying 55 km inshore from the coast line (inner part of the mangrove forest). The static closed chamber technique was implemented at three inter-tidal positions (landward, seaward and bare mudflats) in each station. Fluxes were measured in the daytime every half an hour by circulating chamber headspace air through a sampling manifold assembly and a closed-path non-dispersive infrared gas analyser. The fluxes ranged between 0.15 and 2.34 μmol m^?2 s^?1 during the annual course of sampling. Effluxes of higher magnitude were measured during summer; however, it abruptly decreased during the monsoon. CO₂ flux from the forest floor was strongly related to soil temperature, with the highest correlation found with temperature at 2 cm depth. No such significant relationship between soil water content and CO₂ efflux could be properly ascertained; however, excessively high soil water content was found to be the only reason which hampered the rate of effluxes during the monsoon. On the whole, landward (LW) sites of the mangrove forest emitted more than the seaward (SW) sites. Q ₁₀ values (obtained from simple exponential model) which denote the multiplicative factor by which the efflux rate increases for a 10 °C rise in temperature ranged between 2.07 and 4.05.  相似文献