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Sandip Giri Sudip Manna Abhra Chanda Avirup Chowdhury Anirban Mukhopadhyay Sarbari Chakraborty Sugata Hazra 《Journal of the Indian Society of Remote Sensing》2016,44(1):59-66
Potential fishing zones (PFZ’s) are those regions where the fishes aggregate due to an abundance of food and they are demarcated by tracing those regions in the ocean, where a sharp sea surface temperature (SST) gradient along with optimal chlorophyll (Chl) concentration co-exists at a given time. In this regard, Indian National Centre for Ocean Information Services (INCOIS) disseminates the daily PFZ forecasts in Bay of Bengal and Arabian Sea to aid the fishermen community. The present study is an endeavor to develop a local spatial model derived Potential Fishing Zone (PFZ) in the northern Bay of Bengal (nBoB) lying adjacent to the West Bengal coast. Satellite derived SST and chlorophyll data obtained for two consecutive winter seasons of 2010–11 and 2011–12 were used to generate line density (LD) raster. Shapefiles of INCOIS predicted PFZs were overlaid on these LD raster to extract the corresponding pixel values. Histogram ranges of the extracted pixels were fixed and same values lying in the LD raster of both SST and chlorophyll other than INCOIS PFZs were detected by a spatial model in ERDAS. The PFZs thus derived were validated against the ground fish catch data and it was observed that good fish catch was seen in the model derived additional PFZs also. The catch per unit effort (CPUE) values was found to be very close to that of the CPUE value of PFZ advisories of INCOIS. However, the CPUE in the non PFZ areas were significantly lower than the former two categories. 相似文献
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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
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Ocean Dynamics - Since the 2004 Indian Ocean tsunami and particularly after the 2011 Tohuku tsunami, there has been a significant increase of computer simulation using real-time data; however,... 相似文献
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C M Kishtawal P K Pal M S Narayanan S K Manna O P Sharma Sangeeta Agarwal H C Upadhyaya 《Journal of Earth System Science》1993,102(4):507-519
The impact of moisture anomalies on the circulation of the south-west Indian monsoon has been studied with a general circulation model. Newtonian relaxation is adopted to subject the model atmosphere under sustained moisture anomalies. The impact of negative anomalies of moisture was seen as a divergent circulation anomaly, while the positive anomaly was a stronger convergent anomaly. Although the humidity fields display a resilient behaviour, and relax back to normal patterns 1–2 days after the forcing terms in humidity are withdrawn, the circulation anomalies created by the moisture variation keeps growing. A feedback between positive moisture anomalies and low level convergence exists, which is terminated in the absence of external forcings. 相似文献
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Acta Geotechnica - This paper presents a comparative experimental study highlighting the differences in load transfer mechanism between the connected and disconnected piled raft systems. Scaled... 相似文献
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蓬莱附近 海区水下地形的星载合成孔径雷达遥感 总被引：3，自引：0，他引：3
本文依据山东蓬莱附近海区１９９２年４月１９日的ＥＲＳ－１ＳＡＲ图像，分析了该海区的水下地形并探讨了水下地形雷达成像机理。分析结果显示，ＳＡＲ图像较好地揭示了该海区四人洲、潮待洲、新井洲等水下地形。研究指出，流经水下地形的潮流对海洋表面波的水动力调制是水下地形ＳＡＲ成像的主要机理。 相似文献
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With the advent of mining activities at Raniganj coalfield in India, the natural topography has been defaced in some elongated tracts by either excavation or dumping. This paper deals with opencast mining induced defaced topography of Raniganj coalfield, which needs to be reclaimed properly right after mining. This paper investigated intensity of defacing topography, magnitude of topographic deformations through a number of ex-situ measurement. Consequences of these topographic deformations are also investigated in this study. Through a number of ex-situ measurement based on Geographical Information System (GIS) techniques, generating contour and profiling them over the spoil dumps and excavated lows using fine resolution digital elevation data (Remote Sensing image), a total 132 (85 are abandoned and 47 are working) patches of defaced topography have been identified, which covers 43.26 sq km. surface area. Some working opencast quarries are more than 95 m deep, with an area of more than 2.4 sq km and dumped ridges are more than 60 m high (peak), with area more than 1.5 sq km. In case of abandoned mine (more than 20 years) some quarries are more than 28 m deep with area 0.99 sq km. and some of dumped ridges are more than 28 m high (peak), with area 0.29 sq km. These kinds of defaced surface remain for a long time, such quarries contain acidic logged water and spoil dump leads to acid mine drainage and erosion of loose soil particle. It deteriorates the entire land, water system of the region. The study suggests restoring land right after mining and the area made to be ecologically conformable. 相似文献
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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