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281.
局地云量变化气候效应的数值模拟 总被引:3,自引:3,他引:3
本文用统计得到的东半球夏季平均云量资料,利用改进的云-辐射计算模式,在三维有限区域模式中模拟局地云量变化的气候效应。模拟结果表明,高原地区和热带辐合带云量变化造成的气候效应都主要表现在青藏高原地区。在低反照率时,高原地区云量减少使该地区地表加热,引起高低空气压系统加强;高反照率时结果相反。热带辐合带云量减少会引起青藏高原地区降温和气压系统减弱。 相似文献
282.
283.
王廷秀 《南京气象学院学报》2017,9(4):391-394
本文简要讨论Gronwall不等式的研究进展,并给出关于如下的一类非线性Volterra积分不等式的一个结果:w(u(t))≤g(t))+∑i=1n∫αi(t0)αi(t)fi(t,s)∏j=1mHij(u(s))Gij(maxs-h≤ξ≤s u (ξ))ds. 相似文献
284.
This paper retrieves the yearly and monthly mean 0.75μm aerosol optical depth(AOD) of 41 A-class solar radiation stations over China from 1979 to 1990,and analyzes the spatial and temporal distribution of AOD over China mainland.The data employed are daily direct solar radiation and sunshine duration,as well as the TOMS version-7 ozone observation data in the same time.The results indicate that the Siehuan Basin is the largest center of yearly mean AOD over China.and the other two larger centers lie in Wuhan City and the South Xinjiang Basin,separately.AOD values are also relatively larger in the middle-and-lower reaches area of Changjiang River.Shandong Peninsula and coastal area of Guangdong Province:while in Yunnan Province,coastal area of Fujian Province.most parts of Northwest and Northeast China,AOD values are relatively smaller.The distribution of AOD varies with different months.In most parts of China.the maximum of AOD occurs in spring season;but the minimum varies in different regions,From 1979 to 1990.in the Qinghai-Xizang Plateau,West Siehuan Basin,North Guizhou Province.most areas of the middle-and-lower reaches of Changjiang River,Shandong Peninsula and west part of South Xinjiang Basin.AOD shows an increasing trend.But in Northeast China,most part of Northwest China,Yunnan-Guizhou Plateau,western Guangxi Region and the coastal areas of East China,AOD shows decreasing tendency.Generally,the seasonal variation characteristics of AOD in China can be classified into four typical models,i.e.,mono-modal types A and B,bimodal and Poly-modal. 相似文献
285.
人工触发闪电与降雨倾泻 总被引:1,自引:3,他引:1
根据人工触发阀电后雨量猛增的观测事实,利用一个简单的静电模式计算了闪道附近雨滴的重力碰并增长,结果指出,闪电后降雨猛增必须满足一定的条件,除了要求较高的离子浓度(〉10^14/m^3)外,还取决于闪电所引起的电场变化和闪电被触发后闪道附近环境电场强度的特性。 相似文献
286.
对流和层状云系电活动,对流及降水特性的相关分析 总被引:27,自引:11,他引:27
通过对6次不同云系电特性、回波、对流及降水特性的综合分析,探讨了它们之间的相关性。结果表明:除不稳定能量外,-10℃层和0℃层高度以及他们之间的高度差、0℃层与云顶的高度差也是表征雷暴动力和电特性的重要参量;雷暴云起电过程对冰相作用有较强的依赖性;雷暴中的电活动与对流活动成正相关,闪电多发生在30dBz强回波高度大于-10℃层高度时段内,强烈的电活动与强降雨有很好的对应关系,而与一般性降雨对应关系较差;在雷暴消散期,闪电可能会影响雷暴的特性 相似文献
287.
288.
Weakening of Interannual Variability in the Summer East Asian Upper-tropospheric Westerly Jet since the Mid-1990s 总被引:3,自引:1,他引:3
In this study,we found that the intensity of interannual variability in the summer upper-tropospheric zonal wind has significantly weakened over Northeast Asia and the subtropical western North Pacific(WNP) since the mid-1990s,concurrent with the previously documented decrease of the westerly jet over North China and Northwest China.Corresponding to this weakening of zonal wind variability,the meridional displacement of the East Asian westerly jet(EAJ) manifested as the leading mode of zonal wind variability over the WNP and East Asia(WNP-EA) before the mid-1990s but not afterward.The energetics of the anomalous pattern associated with the meridional displacement of the EAJ suggests that barotropic energy conversion,from basic flow to anomalous patterns,has led to the weakening of the variability in the EAJ meridional displacement and to a change in the leading dominant mode since the mid-1990s.The barotropic energy conversion efficiently maintained the anomalies associated with the variability in the EAJ meridional displacement during 1979-1993 but acted to dampen the anomalies during 1994-2008.A further investigation of the energetics suggests that the difference in the patterns of the circulation anomaly associated with either the first leading mode or the meridional displacement of the EAJ,i.e.,a southwest-northeast tilted pattern during 1979-1993 and a zonally oriented pattern during 1994-2008,has contributed greatly to the change in barotropic energy conversion. 相似文献
289.
Yong Ge Sanping Li V. Chris Lakhan Arko Lucieer 《International Journal of Applied Earth Observation and Geoinformation》2009
The existence of uncertainty in classified remotely sensed data necessitates the application of enhanced techniques for identifying and visualizing the various degrees of uncertainty. This paper, therefore, applies the multidimensional graphical data analysis technique of parallel coordinate plots (PCP) to visualize the uncertainty in Landsat Thematic Mapper (TM) data classified by the Maximum Likelihood Classifier (MLC) and Fuzzy C-Means (FCM). The Landsat TM data are from the Yellow River Delta, Shandong Province, China. Image classification with MLC and FCM provides the probability vector and fuzzy membership vector of each pixel. Based on these vectors, the Shannon's entropy (S.E.) of each pixel is calculated. PCPs are then produced for each classification output. The PCP axes denote the posterior probability vector and fuzzy membership vector and two additional axes represent S.E. and the associated degree of uncertainty. The PCPs highlight the distribution of probability values of different land cover types for each pixel, and also reflect the status of pixels with different degrees of uncertainty. Brushing functionality is then added to PCP visualization in order to highlight selected pixels of interest. This not only reduces the visualization uncertainty, but also provides invaluable information on the positional and spectral characteristics of targeted pixels. 相似文献
290.