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Caroline Dolant Alexandre Langlois Benoit Montpetit Ludovic Brucker Alexandre Roy Alain Royer 《水文研究》2016,30(18):3184-3196
Currently observed climate warming in the Arctic has numerous consequences. Of particular relevance, the precipitation regime is modified where mixed and liquid precipitation can occur during the winter season leading to rain‐on‐snow (ROS) events. This phenomenon is responsible for ice crust formation, which has a significant impact on ecosystems (such as biological, hydrological, ecological and physical processes). The spatially and temporally sporadic nature of ROS events makes the phenomenon difficult to monitor using meteorological observations. This paper focuses on the detection of ROS events using passive microwave (PMW) data from a modified brightness temperature (TB) gradient approach at 19 and 37 GHz. The approach presented here was developed empirically for observed ROS events with coincident ground‐based PMW measurements in Sherbrooke, Quebec, Canada. It was then tested in Nunavik, Quebec, with the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR‐E). We obtained a detection accuracy of 57, 71 and 89% for ROS detection for three AMSR‐E grid cells with a maximum error of 7% when considering all omissions and commissions with regard to the total number of AMSR‐E passes throughout the winter period. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Arkoprovo Biswas 《Journal of the Geological Society of India》2016,88(4):493-502
Inversion of self-potential anomaly for 2-D inclined sheets of infinite horizontal extent has been studied. Least-square inversion and very fast simulated annealing global optimization has been used to model the five parameters of self potential anomaly. The method of least square and very fast simulated annealing global optimization method is compared and analyzed. Very fast simulated annealing can model the noisy and field data of self potential anomaly very precisely than linear inversion technique. However, time taken by very fast simulated annealing inversion is larger than linearized inversion. The comparative analysis has been done on synthetic data (noise free and noisy) and two field data from Bavarian woods anomaly, Germany and Surda anomaly, India to show the efficacy of both the methods. The estimated parameters were compared with those from previous studies using various global optimization algorithms, mainly neural network, genetic algorithm and particle swarm optimization on the same field data sets. It can be concluded that the global optimization algorithms considered in this study were able to yield compatible solutions with those from least-square methods. The present global optimization method is in good agreement with the other global optimization methods in terms of results and computation time. 相似文献
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Cloud — Aerosol interaction during lightning activity over land and ocean: Precipitation pattern assessment 总被引:1,自引:0,他引:1
Jayanti Pal Sutapa Chaudhuri Arumita Roy Chowdhury Tanuka Bandyopadhyay 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(3):251-261
The present study attempts to identify the land - ocean contrast in cloud - aerosol relation during lightning and non-lightning days and its effect on subsequent precipitation pattern. The thermal hypothesis in view of Convective Available Potential Energy (CAPE) behind the land - ocean contrast is observed to be insignificant in the present study region. The result shows that the lightning activities are significantly and positively correlated with aerosols over both land and ocean in case of low aerosol loading whereas for high aerosol loading the correlation is significant but, only over land. The study attempts to comprehend the mechanism through which the aerosol and lightning interact using the concept of aerosol indirect effect that includes the study of cloud effective radius, cloud fraction and precipitation rate. The result shows that the increase in lightning activity over ocean might have been caused due to the first aerosol indirect effect, while over land the aerosol indirect effect might have been suppressed due to lightning. Thus, depending on the region and relation between cloud parameters it is observed that the precipitation rate decreases (increases) over ocean during lightning (non-lightning) days. On the other hand during non-lightning days, the precipitation rate decreases over land. 相似文献
47.
Ananya Roy 《The Professional geographer》2016,68(2):313-321
Recently, in geography and related disciplines, there has been a call to generate conceptual frameworks from the Global South. Such a call does not imply cataloging the diversity and plurality of the world but rather requires new understandings of relationalities and transformations. In this article, I contribute to these ongoing endeavors by thinking from Asia. In doing so, I interpret Asia not as a bounded geographical location but instead as interconnected space. In particular, I pay attention to how such interconnections reference Asian models of development, thereby creating a politics of futurity. A study of the making of Asian futures allows a broader understanding of the renewal of development in a rearranged south–north world. 相似文献
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Roy T. Churchwell Steve Kendall Stephen C. Brown Arny L. Blanchard Tuula E. Hollmen Abby N. Powell 《Estuaries and Coasts》2018,41(1):280-292
River deltas along Alaska’s Beaufort Sea coast are used by hatch-year semipalmated sandpipers (Calidris pusilla) after leaving their terrestrial natal sites, but the drivers of their use of these stopover sites on the first “hop” of fall migration are unknown. We quantified sandpiper temporal distribution and abundance as related to food resources at three river deltas during the beginning of their fall migration (post-breeding period) to compare the habitat quality among these deltas. We conducted population counts, sampled invertebrates, and captured birds to collect blood samples from individuals for triglyceride and stable isotope analyses to determine fattening rates and diet. Patterns of sandpiper and invertebrate abundance were complex and varied among deltas and within seasons. River deltas were used by sandpipers from late July to late August, and peak sandpiper counts ranged from 1000 to 4000 individuals, of which 98% were hatch-year semipalmated sandpipers. Isotopic signatures from blood plasma samples indicated that birds switched from a diet of upland tundra to delta invertebrate taxa as the migration season progressed, suggesting a dependence on delta invertebrates. Despite differences in diet among deltas, we found no differences in fattening rates of juvenile sandpipers as indicated by triglyceride levels. The number of sandpipers was positively associated with abundance of Amphipoda and Oligochaeta at the Jago and Okpilak-Hulahula deltas; an isotopic mixing model indicated that sandpipers consumed Amphipoda and Oligochaeta at Jago, mostly Chironomidae at Okpilak-Hulahula and Spionidae at Canning. Regardless of the difference in sandpiper diets at the Beaufort Sea deltas, their similar fattening rates throughout the season indicate that all of these stopover sites provide a critical food resource for hatch-year sandpipers beginning their first migration. 相似文献
50.
T. P. S. Rawat Madhuparna Roy G. B. Joshi 《Journal of the Geological Society of India》2018,91(1):25-31
Sonrai basin, located along the southwestern margin of Bundelkhand Granite-Gneiss Complex (BGC) is known for its base metal and phosphorite mineralization. Uranium mineralization of appreciable grade and thickness was reported in Pisnari block in the northern part of this basin during sub-surface exploration activity in 1976-97. This was in the form of uranium-bitumin association within fractures in the carbonate-terrigenous sediments of Gorakalan shale, Rohini carbonate and Bandai sandstone of Sonrai Formation of Bijawar Group. Similar mineralization was also noted within the lower chloritic shale member of Solda Formation of the same Group. During subsequent drilling activity at a later phase (2005-09), uranium rich zones within Rohini carbonate and chloritic shale members were corroborated by the interception of mineralized bands in two boreholes drilled near Pisnari. Petrographic study of radioactive core samples reveal that uranium mineralization is closely associated with globular carbonaceous matter and sulphides along the fractures. Uranium is either adsorbed in carbonaceous matter or occurs as ultrafine inclusions of coffinite within carbonaceous matter. An additional phase of secondary uranium mineral (uranophane) is also noted in one of the boreholes. The uranium minerals, in association with sulphides, fill up moderately dipping fractures (approximately 15o towards North) which are oblique to the core axis of the inclined borehole and thus, the mineralization is characterized as hydrothermal fracture-controlled vein type mineralisation. C-HN- S analysis of carbonaceous matter occurring in close association with the uranium minerals reveal heterogeneity in composition with respect to carbon and sulfur. The present paper aims at discussing the geological, petrological and radiometric aspects of this mineralization, so as to enhance the understanding of the same. 相似文献