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51.
湖南省2001年夏秋季对流云降水潜力数值模拟结果 总被引:5,自引:0,他引:5
应用对流云数值模式模拟了2001年7~9月湖南省三个探空站0000和1200(世界时)462个对流云降水算例.模拟结果表明(1)其中53天的198个算例属于有利人工增雨的天气形势,133个算例的可播度大于零,54个算例的增雨率大于零;(2)7~9月天气形势有利于人工增雨日的算例,对流云平均含水量为575万吨,平均降水效率11.4%;(3)8月降水潜力大于7月,9月降水潜力最小.这表明即使大旱的2001年湖南省夏秋季对流云仍然有一定的增雨潜力. 相似文献
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The Influence of Vegetation Cover on Summer Precipitation in China: a Statistical Analysis of NDVI and Climate Data 总被引:18,自引:0,他引:18
This study provides new evidence for the feedback effects of vegetation cover on summer precipitation in different regions of China by calculating immediate (same season), and one-and two-season lagged correlations between the normalized difference vegetation index (NDVI) and summer precipitation. The results show that the correlation coefficients between NDVI in spring and the previous winter and precipitation in summer are positive in most regions of China, and they show significant difference between regions. The stronger one-and two-season lagged correlations occur in the eastern arid/semi-arid region, Central China,and Southwest China out of the eight climatic regions of China, and this implies that vegetation cover change has more sensitive feedback effects on summer precipitation in the three regions. The three regions are defined as sensitive regions. Spatial analyses of correlations between spring NDVI averaged over each sensitive region and summer precipitation of 160 stations suggest that the vegetation cover strongly affects summer precipitation not only over the sensitive region itself but also over other regions, especially the downstream region. 相似文献
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A. Gelencsér A. Hoffer G. Kiss E. Tombácz R. Kurdi L. Bencze 《Journal of Atmospheric Chemistry》2003,45(1):25-33
Current climate models seem to underestimate the flux of solar energy absorbed by the global troposphere. All of these models are constrained with the assumption that cloud droplets consist of pure water. Here we demonstrate in a simple laboratory experiment that aromatic hydroxy-acids which are found in continental fine aerosol can react with hydroxyl radicals under typical conditions prevalent in cloud water influenced by biomass burning. The reactions yield colored organic species which do absorb solar radiation. We also suggest that the products of such reactions may be humic-like substances whose presence in continental aerosol has been confirmed but their source mechanisms are still much sought after. We also attempt to give a first order estimate of the enhancement of water absorption at a visible wavelength under atmospheric conditions. 相似文献
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The effect of elevated nitric acid concentrations on cloud particle number concentrations and sizes of mixed phase cirrus cloud (containing both supercooled liquid and frozen ice particles) is studied using a detailed multicomponent condensation model. Our model calculations suggest that high nitric acid volume mixing ratios (VMRs), corresponding to upper tropospheric measurements, can increase the ice crystal number concentrations substantially especially in the case of freezing of non-activated solution droplets (as opposed to freezing of supercooled cloud droplets). This is due to increased droplet sizes caused by nitric acid absorption and the resulting uptake of water. 相似文献
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