2018年南京梅雨异常及环流分析
投稿时间:2019-12-12  修订日期:2020-02-25  点此下载全文
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作者单位E-mail
金琼 南京市气象局 jinqiong1985@163.com 
戴竹君 南京市气象局 daizhujun99@163.com 
李聪 南京市气象局  
李菁 南京市气象局  
基金项目:华东区域气象科技协同创新基金合作项目
中文摘要:利用自动站降水数据和NCEP/NCAR再分析资料,结合江苏入、出梅指标对2018年南京梅雨进行讨论,并且分析导致当年南京梅雨异常的环流因子,结果表明:1)当年入梅偏晚、出梅正常,梅雨分布不均匀,总量偏少,其中南部异常偏少8成;2)前期南支槽活动频繁,副热带高压相比同期偏南,季节北跳偏迟,且南亚高压主体偏强,位置偏东偏北,易导致入梅偏迟;3)入梅后,副热带高压大幅度北抬,南亚高压东伸明显,加之东北冷涡活动弱,使得冷暖气流交汇偏北,因此江苏沿江地区梅雨量偏少;4)南京地区的梅雨量与6-7月副热带高压的南北跨度具有显著的负相关;5)东亚夏季风偏强时,同年南京中北部地区的梅雨量很可能偏少,对梅雨预报有一定的指示意义。
中文关键词:梅雨,副热带高压,季节北跳,南亚高压,南北跨度,强东亚夏季风
 
Characteristics and associated Circulation Analysis of anormaly Meiyu in 2018 in Nanjing
Abstract:Based on the index of Jiangsu Meiyu, this paper analyzes the characteristics of Meiyu precipitation in Nanjing in 2018 and the associatied circulation causing the anormaly Meiyu, using the daily precipitation data of Nanjing and daily NCEP/NCAR reanalysis data. The results show as follows: 1) The Meiyu in Nanjing in 2018 was characterized with the later beginning date, the nonuniform distribution of Meiyu precipitation in space, and the significantly less amount of Meiyu precipitation (which was 80% less than the climatic mean in the southern Nanjing); 2) The previous trough in westerlies was active, and it causes the Northwest Pacific subtropical high (NPSH) south than normal. In case of that, the seasonal northward of NPSH is late, which results in the late beginning date of Meiyu. Meanwhile, the South Asia high (SAH) in 2018 which is stronger and northeastward than climatic mean is favor to a late beginning of Meiyu. 3) During the period of Meiyu, the ridge of NPSH jumped to north sharply and the SAH was so stronger and northeast than the climatic mean. These mentioned circulation together with the weak activities of northeast China cold vortex led to northward of the meeting between cold air and warm air, as well as significantly less rainfall during Meiyu period in the region along the Yangtze river. 4) The amount of Meiyu precipitation in Nanjing shows negative correlation with the north-south span of the NPSH from June to July. 5) In the years of strong East Asia summer monsoon, the Meiyu precipitation in middle and north of Nanjing is less than the climatic mean. This is useful for the forecast of Nanjing Meiyu.
keywords:Meiyu, Northwest Pacific subtropical high, seasonal northward, South Asia high, north-south span, strong East Asia summer monsoon
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