南沙区2012年7—8月的持续高温过程分析

Analysis of a Sustained High-Temperature Process in July and August of 2012 in Nansha District,Guangzhou

利用南沙气象探测基地的地面常规观测资料对南沙的高温日进行了统计,并对2012年7—8月的高温天气过程做了分析,结果发现:南沙高温日数和持续高温出现最多的是2009年,持续高温以2 d最多,持续时间最长的为3 d;南沙高温主要在6—9月出现,集中出现在7月下旬—8月下旬,高温日出现最多的是8月;高温一般出现在15:00前后。2012年高温出现时副高一般断裂成块状或者脊线比较偏北,受热带气旋的影响较大;所有的高温日都受热带气旋外围下沉气流影响;当热带气旋位于南沙区偏东时,出现高温持续的时间较长,而且过程最高气温也较高。高温日当天08:00气温高、云量偏少、地面风速低、以西到西北风为主,湿度偏低。

Historical high-temperature days are statistically studied for the Nansha district of Guangzhou using the surface conventional observations from a local watch base and analysis is conducted of a high-tem- perature weather process for July and August of 2012. The results showed that 2009 is the year with the largest number of high-temperature days （2d at the most） and the longest sustained high-temperature duration （3d at the most）. In Nansha, high temperature mainly occurs from June to September, with the most concentrated period in late July to late August, and most of the high-temperature days occur in August with the time around 15：00 having the most occurrence. In the case of 2012, the high temperature was associated with a broken-off, lump-shaped subtropical high or northward-located ridge of the high, a pattern that exposed Nansha to large effect of tropical cyclones. All of the high-temperature days were affected by the down- draft at the periphery of tropical cyclones. When tropical cyclones were east of the district, high temperature usually lasted long and experienced relatively high maximum temperature of its life cycle. At 08：00 of the high-temperature days, air temperature was high, cloud amount was low, surface wind speed was small, the wind was mainly west to northwest, and the humidity was low.