Total deformation and its role in heavy precipitation events associated with deformation-dominant flow patterns

In this paper, it is elucidated that the total deformation （TD）, defined as the square root of the sum of squared stretching deformation and squared shearing deformation, is an invariant independent of the coordinate system used. An idealized flow field is then constructed to demonstrate the confluence effect of a non-divergent and irrotational deformation field on moisture transport. To explore the characteristics and role of TD, one heavy rainfall case that occurred in the middle and lower reaches of the Yangtze River （MRYR） over China, associated with a front with shear line, is analyzed using the Weather Research and Forecasting （WRF） model output data. It is found that right before the occurrence of precipitation, the effect of the confluence induced by deformation on moisture transport provides a favorable condition for precipitation. During the precipitation, both location and orientation of the zone of large TD coincide with the confluent shear line. The rainhands are nearly parallel with, and located lightly to the south of the zones of large TD and the confluent shear line. The TD in the lower troposphere increases in value as precipitation persists. When TD approaches its maximal value, the next 6-hour precipitation reaches its peak correspondingly. A tendency equation for TD is derived. The analysis of linear correlation and RMS difference between individual terms in the total deformation equation and the sum of the terms shows that the pressure gradient plays a major role in determining the local change of total deformation.     

THE APPLICATION OF ASSIMILATED AIRCRAFT DATA IN SIMULATING A HEAVY RAIN OVER SOUTH CHINA IN JUNE 2005

Regular and irregular observational data are used to analyze and simulate a torrential rain over the south of China on 18 – 24 June 2005. Since the regular data cannot depict the rainfall system fully, GRAPES model is used to simulate this process. Different data are assimilated for 12 hours by its simulating system and different analysis data are obtained. In order to analyze how well the model forecast has been improved with the addition of assimilated aircraft data, these different analysis data are used as the first-guess data to conduct two control numerical simulation tests. From these tests, it is proved that the model that adds aircraft assimilation data can simulate the main region of precipitation, which is more consistent with the observed precipitation than the model that does not, and that the accuracy rate is also improved. These numerical simulation tests not only show that it is necessary and capable to improve the modeling of this torrential rain process by using aircraft data, but also lays the foundation for forecasting heavy rains in the south of China based on aircraft data.     

1997年南宁市大雨以上降水特点分析

通过对南宁市１９９７年大雨以上降水过程（１７次）的统计分析,找出当年南宁市大雨以上降水的特点。     

南宁市大雨以上强降水的V-3θ结构特征及预报应用

统计分析了1988～2003年南宁市大雨以上强降水过程的V 3θ结构图,结果显示:降水前12～36h有95%的个例达到大雨以上强降水的前兆特征,就大气稳定度条件分析而言,这一结果已经起到较好的预警作用,配合其它动力条件、水汽条件的分析,对提高南宁市强降水的预报准确率有较好的参考价值,可以应用到日常预报业务中。     

用Shepard插值法作大雨过程预报

５，６月全州性大雨是红河州的关键性天气之一。大雨过程预报对红河州工农业生产有着重要的意义。在假定相似大气状况和过程产生的相似结果的基础上，将Ｓｈｅｐ－ａｒｄ插值法引入到大雨过程预报中，试用结果表明，效果显著。     

气象消息与通讯

鲁省大雨山东省境内连日大雨滂沱,滋阳、济宁、曲阜、昌邑、汶上、东平、邹县等二十余县,尽成泽国。(中央社北平七月二十三日哈瓦斯电)西藏南部发生水灾中央社印度西姆拉七月十六日路透电;据昨日息:西藏南部春比山谷带,于十日发生水灾,并有轻微地震,遇难者约二百人,亚东以南之数村,被大水冲没亚东与印度间之电报线亦被冲毁达六英里之遥。川省久旱逢甘雨四川境内本年六月份雨量之少,为前所未见,幸入月(七月)以来,几场大雨,扫除旱象,挽救农作,久旱逢甘霖,殊堪庆幸。兹将六,七月份川省境内之雨量摘录如下:成都六月46.9mm 七月份269.5mm(六月份之46.9mm 为成都近八年来同月雨量之最少者)。乐山六月78.1mm,七月264.8mm     

战争狂与地图的故事

1815年6月18日之夜,是拿破仑滑铁卢决战的前夕．窗外滚滚的雷声和着瓢泼大雨声,未能引起他的冷静思考。拿破仑拿着地图,仔细地研究了小城滑铁卢及其周围的地形、地物,分析了双方兵力的布署,制定了“详细周密”的作战方略．确信第二天的生死决战胜利在握。但是,拿破仑却没有从地图上读出道路状况之差,没有读出自己的阵地是地势低洼的田野,     

南宁市汛期大雨中短期预报消空法研究

通过分析本站近十年来大雨及以上降水天气过程的EC预报场的分布特征,发现其中的部分因子对预报南宁市大雨及以上降水有较好的消空作用.据此制作南宁市大雨预报系统,并给出南宁市大雨预报消空条件和2004年试用情况分析.