【摘要】 1311号强台风尤特登陆后给广东带来持续性大范围强降水,对流降水特征十分显著。文章分析了"尤特"影响期间大尺度环流背景,重点讨论了此次持续性强降水过程中大气层结问题。发现低空急流向广东输送强的暖平流,是广东大气层结不稳定得以持续维持的根本原因。进一步分析发现,低空急流本身并不是"暖"的,当"尤特"趋向陆地时,陆地上的暖气团在"尤特"环流强迫下向南传播扩散,低空急流穿越这一暖区时温度升高才具备"暖"的特性。温度诊断方程结果进一步证实这一点。通过个例反查,在许多登陆后造成连续强降水的台风过程中均发现了这一特征。因此,台风登陆引起环境温度场的演变以及与低空急流的配置需引起业务预报上的重视。更多还原

【Abstract】 Severe Typhoon Utor(No.1311) brings sustained heavy rainfall with extremely strong convective storms to Guangdong after it makes landfall.Based on the observation and the NCAR FNL data,characteristics of large-scale circulation,especially of the atmospheric stratification during the extreme event are studied.It is found that,the maintenance of the instable stratification is mainly due to the warm advection to Guangdong transferred by the low-level jet.Further study reveals a truth that,the low-level jet,originally cold over the sea,is warmed and blows to Guangdong when it moves across a warm air mass,which is forced from the land to the upstream region of Guangdong by the outer circulation of "Utor" while it is approaching Guangdong.The result of temperature diagnosis function confirms it.Similar phenomena are found in many cases which result in sustained torrential rain events after typhoons land.Therefore,the variation of the temperature field and the low-level jet caused by the landfall of typhoon should be paid more attention to in forecasting operations.更多还原