庐山2002—2010年夏季强降水特征分析

利用气象观测资料,对庐山2002—2010年夏季(7—9月)强降水(日降水量≥50 mm)进行了统计分析和天气系统分型,并对降水期间的气象要素变化、卫星云图及雷达回波特征进行了归纳分析。结果表明,(1)庐山夏季强降水日数平均每年为2.8 d,少约1 d,多达5 d。四类天气系统中台风占44%,西风带占32%,副热带高压边缘占16%,东风波占8%。(2)强降水过境时的要素变化,不同系统有不同的表现形式,台风影响时会出现降压、降温、增湿、风向旋转、风速增大以及较山下大几倍至几十倍的降水等要素变化;西风带系统影响时,会出现气温明显下降、气压前降后升的过程;副热带高压边缘影响时,前期高温、气压无明显波动,降水以午后到傍晚雷阵雨为主,常伴有短时强降水和强雷电;东风波系统影响时,要素反应弱,降水既有副热带高压边缘的强降水,又有台风性质的大降水。(3)台风系统云图主要表现为螺旋状结构和中尺度对流云团结构,雷达回波表现为混合型降水;西风带系统则呈东北—西南带状云系和带状回波分布;副热带高压边缘在午后到傍晚有一些分散的对流云团不断生消,较少移动,雷达图上午后到傍晚有分散的对流性回波发展;东风波自东向西移动,有带状云系相配合,带来明显的强降水,利用雷达也可以监测到南北向回波带自东向西移动。

CHARACTERISTIC ANALYSE OF 2002—2010 SUMMER HEAVY PRECIPITATION IN LUSHAN

The meteorological observation data are used to statistically analyze and classify the summer rainfall in Lushan,and then,to sum up the variations of meteorological factors,features of satellite cloud pictures and radar echo during precipitation.The results show that（1） Summer（July—September） heavy precipitation events in Lushan occur about 2.8 days per year,with the least 1 day and the most 5 days.Four types of weather system accompany with these heavy rain events,typhoon type（44%）,westerly type（32%）,subtropical high edge type（16%） and easterly wave type（8%）.（2） During heavy precipitation,pressure and temperature decrease,humidity and wind speed increase,and wind direction rotates.（3） For typhoon type,spiral-structure clouds and mesoscale convective clouds occur in satellite cloud pictures,while mixed precipitation appears in radar echoes;for westerly type,there are always northeast-southwest band clouds;for subtropical high edge type,some scattered convective clouds develop and disappear and seldom move during afternoon to evening,and scatter convective radar echo can be seen;and for easterly wave type,accompanied by belt cloud,the wave shifts from east to west and bring obviously heavy precipitation.A north-south orientation echo bands moving from east to west can also be monitored by radar.