The impact of northern Indian Ocean rivers on the Bay of Bengal using NEMO global ocean model     

Srivastava Atul  Gera Anith  Momin Imran M.  Mitra Ashis Kumar  Gupta Ankur 《海洋学报(英文版)》2020,39(3):45-55

The effect of river runoff over the northern Indian Ocean(NIO) especially over the Bay of Bengal(Bo B) has been studied using global Nucleus for European Modelling of the Ocean(NEMO). Two sensitivity experiments, with and without river runoff are conducted and the influence of river runoff on the Indian Ocean hydrography,stratification and circulation features are studied. It is found that due to river runoff surface salinity over the northern Bo B decreases by more than 5 and the East India Coastal Current strengthens by 2 cm/s during post monsoon season. The fresh river water reaches up to 15°N in the Bo B and is the main cause for low salinity there.Sea surface temperature in the northwestern Bo B increases by more than 0.2℃ due to the river runoff in summer monsoon while surface cooling upto 0.2℃ is seen in north-west part of Bo B in winter season. The seasonal mixed layer depth in the region is found to be dependent on river runoff. The effect of vertical shear and Brunt Vaisala frequency on stratification is also examined. The ocean water becomes highly stratified up to 3 035 m due to the river runoff. It is found that the energy required for mixing is high in the northern and coastal Bo B.  相似文献   

Collapsing supra-massive magnetars: FRBs,the repeating FRB121102 and GRBs     

Patrick Das Gupta  Nidhi Saini 《Journal of Astrophysics and Astronomy》2018,39(1):14

Fast Radio Bursts (FRBs) last for \(\sim \) few milli-seconds and, hence, are likely to arise from the gravitational collapse of supra-massive, spinning neutron stars after they lose the centrifugal support (Falcke & Rezzolla 2014). In this paper, we provide arguments to show that the repeating burst, FRB 121102, can also be modeled in the collapse framework provided the supra-massive object implodes either into a Kerr black hole surrounded by highly magnetized plasma or into a strange quark star. Since the estimated rates of FRBs and SN Ib/c are comparable, we put forward a common progenitor scenario for FRBs and long GRBs in which only those compact remnants entail prompt \(\gamma \)-emission whose kick velocities are almost aligned or anti-aligned with the stellar spin axes. In such a scenario, emission of detectable gravitational radiation and, possibly, of neutrinos are expected to occur during the SN Ib/c explosion as well as, later, at the time of magnetar implosion.  相似文献   

Identification of Suitable Natural Calibration Test Site for the Calibration of IRS Optical Sensors     

Shailendra S. Srivastava  Yogdeep Desai  K. S. S. Sekhar  V. R. Bhavsar  Shambhu Singh Tak  Maneesha Gupta  N. K. Vyas  K. V. S. Badarinath  B. Kartikeyan 《Journal of the Indian Society of Remote Sensing》2016,44(3):307-319

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An efficient application of fusion approach for hot spot detection with MODIS and PALSAR-1 data     

Tasneem Ahmed  Shweta Gupta  Balasubramanian Raman 《国际地球制图》2016,31(7):715-738

Hot spot detection with satellite images, especially with synthetic aperture radar (SAR) images is still a challenging task. Several researchers have used TM/optical data for identification of hot spot but the use of SAR data is very limited for this type of application. The fusion of SAR data with TM/optical data may add additional information which in turn will lead for enhancement of detection capability of the hot spot. Therefore, this study explores the possibility of fusion of Moderate Resolution Imaging Spectroradiometer (MODIS) and Phased Array L-band Synthetic Aperture Radar (PALSAR) satellite images for the hot spot detection. Image fusion is emerging as a powerful tool where information of various sensors can be used for obtaining better results. For this purpose, vegetation greenness and roughness information which is obtained from MODIS and PALSAR satellite images, respectively, are used for fusion, and then, a contextual-based thresholding algorithm is applied to the fused image for hot spot detection. The proposed approach comprises of two steps: (1) application of genetic algorithm-based scheme for image fusion of MODIS and PALSAR satellite images, and (2) classification of the fused image as either hot spot or non-hot spot pixels by employing a contextual thresholding technique. The algorithm is tested over the Jharia Coal Field region of India, where hot spot is one of the major problems and it is observed that the proposed thresholding technique classifies the each pixel of the fused image into two categories: hot spot and non-hot spot and the proposed approach detects the hot spot with better accuracy and less false alarm.  相似文献   

Effect of sensor modelling methods on computation of 3-D coordinates from Cartosat-1 stereo data     

Mritunjay Kumar Singh  R.D. Gupta  Snehmani  Anshuman Bhardwaj  Ashwagosha Ganju 《国际地球制图》2016,31(5):506-526

The orbital and the rational polynomial coefficients (RPC) models are the two most commonly used models to compute a three-dimensional coordinates from an image stereo-pair. But it is still confusing that with the identical user provided inputs, which one of these two models provides more accurate digital elevation model (DEM), especially for mountainous terrain. This study aimed to find out the answer by evaluating the impact of used models on the vertical accuracy of DEM extracted from Cartosat-1 stereo data. We used high-accuracy photogrammetric DEM as the reference DEM. Apart from general variations in statistics, surprisingly in a few instances, both the DEMs provided contrasting results, thus proving the significance of this study. The computed root mean square errors and linear error at 90% (LE90) were lower in case of RPC DEM for various classes of slope, aspect and land cover, thus suggesting its better relative accuracy.  相似文献   

Biosafety assessment of municipal wastewater after treatment by <Emphasis Type="Italic">Serratia</Emphasis> sp. ISTVKR1     

A. Gupta  I. S. Thakur 《International Journal of Environmental Science and Technology》2018,15(10):2095-2106

The previously described potent biodegrading bacterial strain Serratia sp. ISTVKR1 isolated from sludge of Vasant Kunj Sewage Treatment Plant (VK STP) was used for the study of detoxification of municipal wastewater contaminants with the help of in vitro bioassays conducted on human liver cancer cell line HepG2. The strain has previously been shown to reduce wastewater contaminant load as revealed by a sevenfold reduction in COD and removal of some organic contaminants in the GC–MS analysis of wastewater post-72-h bacterial treatment. Cytotoxicity, genotoxicity and dioxin-like behavior of real municipal wastewater (collected from inlet of VK STP) was assessed before and after bacterial treatment using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline comet and 7-ethoxyresorufin-O-deethylase (EROD) assays, respectively. The bacterial strain was inoculated into MSM broth (pH = 7.2) containing 50% v/v filter-sterilized influent of VK STP and incubated up to 240 h at 30 °C and 130 rpm. Physicochemical and toxicological analyses were performed for the culture samples. The results of bioassays revealed an increase in cell viability by 40.16% and a reduction in the % EROD activity by 58.4% in the 240-h bacteria-treated sample as compared to the 0-h sample. Genotoxicity as indicated by tail moment (TM) and olive tail moment (OTM) was found to reduce by five- and threefold, respectively, after 240-h bacterial treatment. The results of the study confirmed the potency of the bacterial strain in detoxification of wastewater contaminants.  相似文献   

Holocene tectono-geomorphic evolution of Haryana plains,Western Ganga plain,India     

Pitambar Pati  Vivekanand Acharya  Aditya Kumar Verma  Narendra Kumar Patel  Rajendra Prasad Jakhmola  Chinmay Dash  Vijay Sharma  Ankit Gupta  Brahm Parkash  Arun Kumar Awasthi 《Arabian Journal of Geosciences》2018,11(13):361

Haryana plain is the drainage divide between the Ganga plain in the east and the Indus plain in the west. Being a part of the Himalayan foreland, its geomorphology, sedimentation processes, and tectonism are broadly controlled by the Himalayan tectonics. Soil and geomorphological mapping in Haryana plain bring out geomorphic features such as paleochannels, various active drainage patterns, and landforms such as old fluvial plains, floodplains, piedmonts, pediments, terminal fans, and eolian plains. Based on the degree of soil development, and Optical stimulated luminescence (OSL) ages, the soil-geomorphic units were grouped into six members (QIMS-I to VI) (Quaternary Indus Morphostratigraphic Sequence) of a morphostratigraphic sequence: QIMS-VI 9.86–5.38 Ka, QIMS-V 5.38–4.45 Ka, QIMS-IV 4.45–3.60 Ka, QIMS-III 3.60–2.91 Ka, QIMS-II <?2.91–1.52 Ka, and QIMS-I <?1.52 Ka. OSL chronology of different geomorphic features suggests six episodes of tectono-geomorphic evolution in the region since 10 Ka. Neotectonic features such as nine faults, two lineaments, and five fault-bounded tectonic blocks have been identified. Independent tilting and sagging of the blocks in response to neotectonics have resulted in modification of landforms, depositional processes, and hydro-geomorphology of the region. Major rivers like the Yamuna, the Ghaggar, and the Sutlej show different episodes of shifting of their courses. Lineament controlled few extinct channels have been recorded between 20 and 25 m depth below the surface in the ground-penetrating radar (GPR) profiles. These buried channels are aligned along the paleo-course of the Lost Saraswati River interpreted from the existing literature and hence are considered as the course of the lost river. Seven terminal fans have been formed on the downthrown blocks of the associated faults. The Markanda Terminal Fan, the first of such features described, is indeed a splay terminal fan and was formed by a splay distributary system of the Markanda River. Association of three terminal fans of different ages with the Karnal fault indicates the segment-wise development of the fault from west to east. Also, comparison with other such studies in the Ganga plain to further east suggests that the terminal fans formed by streams with distributary drainage pattern occur only in semiarid regions as in the present area and thus are indicators of semiarid climate/paleoclimate. Though the whole region is tectonically active, the region between the Rohtak fault and Hisar fault is most active at present signified by the concentration of earthquake epicenters.  相似文献   

Proterozoic Orogens of India — A Critical Window to Gondwana     

Saibal Gupta 《Journal of the Geological Society of India》2018,91(2):249-249

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Evaluation of spatial probability of landslides using bivariate and multivariate approaches in the Goriganga valley,Kumaun Himalaya,India     

Kumar  Sandeep  Gupta  Vikram 《Natural Hazards》2021,106(3):2461-2478

Natural Hazards - In this study, new hybrid artificial neural network (ANN) models were used for predicting the groundwater resource index. The salp swarm algorithm (SSA), particle swarm...  相似文献   

Foreword     

Alok K. Gupta 《Journal of Earth System Science》1990,99(1):1-4

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