【作者】 廖向花；

【导师】 周毓荃； 王式功；

【作者基本信息】 兰州大学 ， 气象学， 2010， 硕士

【摘要】 为提高重庆冰雹天气的分析预报能力,加强多源气象资料在重庆冰雹天气过程中的应用,本文利用重庆34个区县较长序列的县志资料、34个气象站灾情资料、MICAPS常规天气资料,研究了重庆近50年的冰雹气候特征,摸清了其时空分布规律；首次对重庆冰雹天气过程进行了划分,总结了有利于重庆冰雹天气发生的环流分型和主要环境形势特征,同时给出了冰雹移动主要路径。利用2008-2009年的多普勒雷达资料和FY-2C卫星及反演产品等遥感资料,初步研究了2008-2009年的典型冰雹个例,探讨多普勒雷达和卫星反演产品在重庆冰雹天气预测分析方面的应用,得到一些识别冰雹云的指标,便于人影防雹业务中的应用；同时,利用多源气象资料深入细致的分析了2008年6月5日一次典型冰雹天气过程的热力、动力天气背景、雷达回波特征及冰雹云系的宏微观结构特征、发展演变规律以及产生的物理机制。主要研究内容和结论如下：重庆冰雹天气的气候统计特征分析表明：重庆冰雹在空间上存在东多西少的特征,东北部山区是冰雹频发地；近50年冰雹具有“少-多-少-多”的非均匀周期变化趋势,80年代后明显增多；年变化呈“双峰型”分布,高峰期为4-5月和7-8月,6月相对较少。重庆冰雹天气以局地对流为主,系统性对流次之,产生系统性对流天气的环流背景分为三类,即低涡型、西北气流型和高空低槽型,其中西北气流型是主要影响系统,约占62%。研究得出重庆冰雹移动路径共9条,绘制了冰雹路径图并提出了人工防雹的对策建议,以提高人影作业的科学性和有效性。利用MICAPS常规天气资料、卫星云图及反演产品、多普勒雷达资料等对2008年6月5日发生在重庆的一次超级单体风暴进行了综合分析。结果表明,该超级单体是在典型的“上层干冷、下层暖湿”的大气垂直结构下产生的,产生风雹的区域正好位于低空急流出口区及中低层风速辐合区。在多普勒雷达产品中表现为典型钩状回波、低层有界弱回波区和“穹隆”、中气旋、阵风锋等超级单体特征。分析还发现,垂直累积液态水(VIL)的突然跃增一般比冰雹降落时间提前2-3个体扫,该产品对冰雹预报具有一定的指示意义。另外,本文利用FY2C卫星反演参数产品对此次风雹过程进行了分析,初步认为,云粒子有效半径能比较细致的反映中小尺度的云微物理结构,其大值区与冰雹落区较为一致,对冰雹落区的分析具有一定的意义；云中大于36μm的粒子越多、所占比重越大,降雹的可能性就越大。利用雷达回波识别冰雹云应综合分析,从回波强度、回波顶高、VIL值及特征、冰雹指数、速度场特征等全方位考虑。其监测预警主要指标为：①回波强度大于50dbz；②回波顶高大于11km；③VIL值大于44 kg/m2以上；④VIL存在≧15kg/m2的明显跃增且跃增后VIL≥50kg／m；⑤冰雹指数出现连续几个实心三角标志；⑥具有强的风速辐合或者中气旋。其中,VIL值的跃增特征及高值能提前2-3个体扫对冰雹天气进行预测,对冰雹的短时临近预报及人工防雹时机的选择具有较高的应用价值。探讨了卫星反演产品在重庆冰雹方面的应用,初步给出了卫星反演产品识别冰雹云的特征参数,其监测预警主要指标为：①云顶高度＞9km,云顶温度＜-30℃；②有效粒子半径＞36μm；③云光学厚度＞30；④液水含量＞700g/m2。特别是有效粒子半径产品,出现有效粒子半径很大且大粒子所占比重很高时,降雹可能性大。本文相关分析研究有助于加深对重庆冰雹天气特征的全面认识、提高冰雹预测能力和人工防雹作业条件的识别能力。更多还原

【Abstract】 The climate characteristics and the spatiotemporal distribution of hail in Chongqing in nearly 50 years have been analyzed in order to improve the weather analysis and forecast the hail over Chongqing, to strengthen multi-source meteorological data in Chongqing hail of application, with a long series of historical meteorological records from 34 counties of Chongqing and MICAPS conventional weather chart from 34 meteorological stations in Chongqing.For the first time hail weather processes are sorted; The beneficial circulation background and main environmental field characteristics are summarized; and the motion pathes of hail are given.In addition, by using doppler radar data and FY2C satellite retrival products between 2008 and 2009 years, we analyse all typical examples of hail during this period, explores the application in the hail forecasting and analysis in Chongqing with Doppler radar and satellite retrieval products.At the same time, we analyse intensively some characteristics of a typical case of hail on June 5,2008,such as the thermal structures, dynamic background and physical mechanism, radar echo characteristics, the hail cloud macro-and micro-physical structures and the evolution regulation.The main research contents and results are as follows.In the paper we analyze the statistical characteristics of the climate in Chongqing hail. The results show that the hail of chongqing in eastern is more than in western.northeast of the most frequent; the hail days vary is heterogeneous in the past 50 years,and has significant increasing after 1980s; inter-monthly variation of hail shows the double peaks, one peak from April to May and the other from July to August. The analysis also shows that hail weather focus on local convection and systematic convection takes second place. The circulation background of systematic convection has three types including cold vortex, northwest airflow and upper trough, the northwest airflow is about 62%. In addition, this study also gives nine motion paths of hail and puts forward some ways to improve the effectiveness of weather modification.Using CINRAD-SA Doppler radar data and MICAPS conventional weather chart, as well as FY2C Satellite retrival products, a supercell storm occurring in Chongqing on June 5,2008 is analyzed. The result shows that the super-cell storm generated by the mechanism of the typical "the upper-level is dry and cold, as well as the low-level is warm and wet", and hail shooting region is located in the export zones of low-level jet and wind convergence area. There are many supercell features of Doppler radar echoes, such as hookecho, bounded weak echo region, vault, meso-cyclone, gust front and etc. We also find that the vertical integration of liquid water content(VIL) increasing abruptly is ahead of two or three volume scan, this result has certain indicating significance on hail forecasting.On the other hand, the paper makes an assay of the supercell storm based on the retrival products of FY2C satellite, and we think that the products of cloud effective particle radius can carefully describe the meso and small scale cloud microphysical structure, its great value is consistent with hail shooting area, and the result is important to hail forecasting.Radar echo identification of hail cloud should be comprehensively analysed, from the aspacts of echo intensity, high echo top, VIL values and characteristics, hail index, velocity field characteristics of all-round consideration. The key indicators of monitoring and warning are as follows:echo intensity is greater than 50dbz; tall of echo top is over 11km; the VIL value is greater than 44 kg/m2; the VIL value-added is more than 15kg/m at a volume scan and then the VIL value is over 50kg/m; Hail index products are solid triangles during a few consecutive sweeps; there are some strong wind convergence or mesoscale cyclone.In addition, the abrupt increasing of vertical integration of liquid water content(VIL) is ahead of two or three volume scan, this result has certain indicating significance on hail forecasting and timing of artificial hail suppression operations.In the paper we first explore the application of satellite retrieval products in Chongqing hail and initially give some identification Hail feature parameters. The monitoring and warning key indicators are as follows:cloud top height is over 9km, cloud top temperature is below-30℃;cloud effective particle radius is over 36μm; cloud optical thickness is over 30; liquid water path is over 700g/m. In particular, the cloud effective particle radius product is most useful, and the possibility of hailfall is large, on the condition that the cloud effective particle radius is very great and the proportion of big particles is very high.These correlation studies are beneficial to deepen our comprehensive knowledge of hail climate characteristics in Chongqing, to improve the hail forcasting ability and to enhance the capability of identifying operating conditions of artificial hail suppression, as well as to expand the application fields of satellite retrieval products.更多还原