2008年深圳洪涝灾害的气候背景和环流条件

用NCC/CMA资料分析了2008年6月深圳降水异常事件的成因,结果认为:2007年7月—2008年2月赤道西太平洋海表温度异常偏低、2008年前冬今春青藏高原积雪面积偏大是深圳异常降水事件的前期气候背景;2008年6月东亚阻塞高压的异常强大及乌拉尔山长波槽的异常加深发展,促进了经向环流异常增强;偏强的冷空气以阶梯槽的形式频繁入侵华南,为深圳异常降水事件提供了动力条件。副高西段较常年偏南,西伸脊点偏东;强劲的季风潮为深圳地区输送了巨大的水汽和热量;冷暖空气在华南地区的频繁交汇与维持是深圳异常降水事件的主要成因。上述多种因素的异常共同导致了深圳异常降水事件的发生。

The great floods in Shenzhen in 2008

The cause of unusual precipitation in Shenzhen in June of 2008 has been analysed by using NCC, CMA data. The results show that the early stage climate background of this unusual precipitation was due to abnormally low sea surface temperature in west Paciifie equator during July 2007- Feb.2008 and larger scale area of accumulated snow in Qinghui-Tibet Plateau during spring and last winter in 2008. Dynamic condition of this unusual precipitation was provided by abnormally strong east Asic blocking high and unusnal development of Ural long-wave trough during June 2008, the strengthening of latitudal circulation lead to stronger cold air invading south China as stepped trough. West part of subtropic high appeared to be unclined to south frequently and ridge point moved east appeared to be inclined to east and strong monsoon surge could transport huge vapor and heat. Frequent confluence and main-tenance of cold and warm airmasses in south China became the main cause of unusual rainfall in Shenshen. All above mentioned factors have caused the Shenshen unusual preapitation event in June of 2008.