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Sandip K. Chakrabarti Ritabrata Sarkar Debashis Bhowmick Arnab Bhattacharya 《Experimental Astronomy》2017,43(3):311-338
Indian Centre for Space Physics has taken a novel strategy to study low energy cosmic rays and astrophysical X-ray sources which involve very light weight payloads up to about five kilograms on board a single or multiple balloons which are used for meteorological purposes. The mission duration could be anywhere from 3-12 hours. Our strategy provides extreme flexibility in mission preparation and its operation using a very economical budget. There are several limitations but our innovative approach has been able to extract significant amount of scientific data out of these missions. So far, over one hundred missions have been completed by us to near space and a wealth of data has been collected. The payloads are recovered and are used again. Scientific data is stored on board computer and the atmospheric data or payload location is sent to ground in real time. Since each mission is different, we present here the general strategy for a typical payload and provide some results we obtained in some of these missions. 相似文献
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HABIB Ammara CHEN Bin SHI Guangyu IWASAKA Yasunobu NATH Debashis KHALID Bushra TAN Saichun MAHMOOD Tariq JIAO Reguang NTWALI Didier 《大气和海洋科学快报》2019,(1):12-20
塔克拉玛干沙漠是亚洲沙尘气溶胶的重要源地。为探讨塔克拉玛干地区沙尘气溶胶的理化特性与时空变化,研究其环境与气候效应,本文分析了四个季节在中国敦煌(塔克拉玛干沙漠内)取得的探空气球观测数据,包括气溶胶的数浓度、粒径分布、质量浓度及在西风主导下的水平输送通量。气溶胶数浓度的垂直廓线显示,来自沙漠地区的矿物粒子对局地环境与气候有重要影响,且所有季节都存在长距离输送。粒子谱分布显示局地有大量粗粒子输入。结果说明,源于塔克拉玛干沙漠的沙尘气溶胶的背景输送有着重要的科学意义,需进一步研究其对东亚和西太平洋地区环境与气候的影响。 相似文献
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网格化历史耕地数据集能为历史时期耕地变化研究提供更精确的支持,并且为全球环境气候变化研究模型模拟提供驱动数据。本文综合考虑了中国历代土地利用开发的特点及自然人文因子对耕地的影响,设计了一套对中国耕地先分区再分层分配的网格化方法。基于国内3个主流区域耕地数据研究成果,采用上述方法建立了1820年(清仁宗嘉庆二十五年)和1936年(民国二十五年)中国10 km×10 km分辨率的耕地数据集,并绘制了分布图。本文还利用国内具有代表性的区域数据集对重建结果进行对比验证。结果表明,该方法可以保证耕地数量的权威性,并且建立具有区域性的高精度历史耕地数据集。 相似文献
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Sudip Jyoti Sahu Bibhash Nath Sharmi Roy Biswapati Mandal Debashis Chatterjee 《Environmental Earth Sciences》2012,65(3):813-821
Groundwater contaminated with arsenic (As), when extensively used for irrigation, causes potentially long-term detrimental
effects to surface soils. Such contamination can also directly affect human health when irrigated crops, such as rice, vegetable
and fruits, are used for human consumption. Therefore, an understanding of the leaching behavior of As in surface soils is
of high importance, because such behavior may increase the bioavailability of As in the soil horizon. In this study, we have
investigated the role of phosphate ions in leaching and bioavailability of As in the soil horizon, where drinking groundwater
contains elevated levels of As (≥50 μg/L). Soil and groundwater samples were characterized in the laboratory and measured
for physical and chemical constituents. The soils are generally neutral to slightly alkaline in character (pH range 7.5–8.1)
with low to moderate levels of free Fe2O3, Al2O3, CaCO3, organic carbon, and clay content. The measured electrical conductivity (mean 599 μS/cm) of the soils demonstrates their
non-saline nature. The Eh values (range −37 to −151 mV) of the groundwater indicate anoxic condition with low to moderate
levels of bicarbonate (range 100–630 mg/L) and phosphate (range 0.002–4.0 mg/L). The arsenic content (range 50–690 μg/L; mean
321 μg/L) in groundwater has exceeded both WHO recommended guideline values (10 μg/L) and the National safe drinking water
limit (50 μg/L). Regression analyses demonstrate that the bioavailability of As in the soil horizon is mainly controlled by
the composition of free Fe2O3 and CaCO3 content of the soils. However, application of P could increase bioavailability of As in the soil horizon and become available
to plants for uptake. 相似文献
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Natural Hazards - Flooding events in the Lower Benue valley of Nigeria are often associated with huge damage to properties and loss of life in the adjoining communities. Specific objectives of this... 相似文献
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M. Venkat Ratnam M. Roja Raman Sanjay Kumar Mehta Debashis Nath B.V. Krishnamurthy M. Rajeevan S. Vijaya Bhaskara Rao D. Narayana Rao 《Journal of Atmospheric and Solar》2011,73(7-8):731-740
To investigate the sub-daily variation in Tropical Easterly Jet (TEJ), a few special experiments have been conducted with mesosphere–stratosphere–troposphere (MST) radar located at Gadanki(13.5°N, 79.2°E) under Study on Atmospheric Forcing and Responses (SAFAR) campaign during 2008–2009. Large sub-daily changes in the TEJ characteristics are observed within a day in addition to day-to-day changes. Based on this observational study, three possible mechanisms for the sub-daily variations are proposed i.e., (1) motion of TEJ core, (2) large updrafts and downdrafts, and (3) strong wave activity. Interestingly, TEJ peak altitude is seen above the Cold Point Tropopause altitude for about 42% of the days. 相似文献