近60年华北春季干旱特征及其与北大西洋海表温度的关系
投稿时间:2020-02-19  修订日期:2020-04-08  点此下载全文
引用本文:
摘要点击次数: 59
全文下载次数: 0
作者单位E-mail
臧迪 南京信息工程大学 489645692@qq.com 
郑有飞 南京信息工程大学  
张顾炜 南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心 kobezane24@hotmail.com 
基金项目:国家重点研发计划(2017YFA0603804);国家自然科学基金项目(41575085,41430528)
中文摘要:利用观测统计分析和CAM 5.3数值模拟相结合的方法,本文基于标准化降水蒸散指数(standardized precipitation evapotranspiration index, SPEI)分析了1955-2018年华北地区春季干旱特征,并重点探讨了北大西洋产生的影响,得到的主要结论如下。华北春季干旱的主要空间分布型为全区一致型,近60年春季华北存在22年偏旱和14年偏涝。华北春季偏旱年主要的大气环流特征是大陆暖高压增强,高空西风急流减弱和华北位于下沉运动区中。观测分析和数值模拟结果均表明,春季北大西洋海温偏暖容易导致华北地区发生干旱:当春季北大西洋为关键海区偏暖,其上空高度场被抬升,激发了一条自北大西洋经欧亚大陆至华北地区的“+ - +”的波列,其波列中心分别位于北大西洋、欧洲大陆-西亚和西北-华北地区上空,这条波列最终导致了西北-华北上空大陆高压增强,华北位于高压底部,上空高度场抬升,西风急流减弱,引发下沉运动,导致空气绝热增温,同时,西风急流减弱导致西南暖湿气流减弱,水汽不易到达华北地区,不利于降水产生,高温少雨有利于干旱发生;当北大西洋偏冷时,波列中心发生了“翻转”,由“+ - +”转变为“- + -”,此时大陆高压减弱,西风急流增强,不利于干旱发生。
中文关键词:华北地区  春季干旱  北大西洋  波列
 
Characteristics of Spring Drought in North China Over the Recent 60 Years and Its Relationship with Sea Surface Temperature in North Atlantic
Abstract:Based on the standardized precipitation evapotranspiration index (SPEI), this study used statistical observational analysis and numerical simulations (CAM 5.3) to analyze the characteristics of spring drought in North China (NC) from 1955 to 2018 and the impacts of North Atlantic (NA). The results showed that the main spatial distribution pattern of spring drought in NC was uniform in the whole region, and there were 22 drought years and 14 flood years in recent 60 years. The main atmospheric circulations of the NC spring drought years were the enhanced continental high, the weakened upper westerly jet and the downward movement in NC. Besides those, both observational analysis and numerical simulation results showed that warm sea surface temperature (SST) in NA could cause the spring drought in NC. The mechanism is as follows: warm SST in NA can lead a ‘ - ’ wave train like ‘Silk Road Pattern’ with its center above NA, Europe-Western Asia and NC; this wave train would enhance the continental high over NC which could cause the downward movements; the downward movements are not conducive to precipitation and will lead to the air adiabatic heating; in addition, NC lies to the south of the upper anticyclone circulation which lead NC is controlled by the northeast airflow which means the warm and humid airflow from the southwest is weakened. In summary, the wave train cause the high temperature and less rain in the NC which is conductive the drought. When the SST in NA gets cold, the center of the wave train would be reversed which would cause the continental high over NC weakened.
keywords:North China, Spring drought, North Atlantic, Wave trains
  查看/发表评论  下载PDF阅读器