摘要
利用1981-2013年长江中下游地区90个气象观测站的逐日气温和降水资料、NCEP/NCAR逐日再分析资料及ERSSTv4海温资料,对2013年夏季发生于长江中下游地区的异常高温干旱事件基本特征及其可能影响机制进行了讨论。结果表明:(1)降水量较同期偏少49.43%,7月中、下旬出现旱情并逐步发展,8月上、中旬旱情最为严重,整体呈现中到重旱,局部地区达到特旱,气温偏高5℃以上;(2)受负EAP/PJ(东亚太平洋型/东亚日本型)遥相关型影响,西太平洋副热带高压(下称西太副高)面积偏大、西伸脊点异常偏西、强度偏强,长期控制长江流域,是诱发此次高温干旱的直接成因;东亚夏季风偏强、副热带西风急流偏北,致使长江流域暖湿空气偏强而冷空气不足,加之下沉气流影响,不利于形成降水。(3)8月第1候至第2候,受负"Silk Road"(丝绸之路)遥相关型影响,源自北大西洋的Rossby波沿急流波导区向东频散至东亚-太平洋地区,加强了负EAP/PJ遥相关型中高纬度两个高度异常中心,对其形态的维持与发展起着重要作用,将西太副高的异常发展推向鼎盛时期;(4)西太平洋暖池区海温异常偏高是负EAP/PJ遥相关型长期维持的重要原因;而7月北大西洋海温异常偏高与西风急流异常偏北密切相关,是影响东亚季风系统各成员配置的又一可能成因。
Based on the daily temperature and precipitation data of 90 stations from 1981 to 2013 in the middle and lower reaches of Yangtze River（ MLRYR） in China,the NCEP/NCAR daily reanalysis data and monthly NOAA Extended Reconstructed Sea Surface Temperature v4（ ERSSTv4） data,the general characteristics and effect mechanism of the continuous hot-dry weather occurred in MLRYR during the summer of 2013 had been investigated. The results were shown as follows：（ 1） The rainfall was less 49. 43% than the historical average. A drought was started in the middle and last dekad of July and then developed gradually,the most severe drought was happened in the first and middle dekad of August while the whole MLRYR was caught in moderate to severe drought,some local areas of MLRYR were reached special drought with the daily mean temperature on the high side 5 ℃.（ 2） Affected by the negative phase of EAP（ East Asia Pacific）/PJ（ Pacific Japan） teleconnection,WPSH（ western Pacific subtropical high） was larger,stronger and the position was westward than normal,controlled MLRYR for a long time,which was one of the most direct reasons for why the heat wave and drought happened. Because of the strong EASM（ East Asian summer monsoon） and northward EASWJ（ East Asian subtropical westerly jet）,the warm-moist and cold-dry air did not match in MLRYR,combined with the descending motion effects,which was not conducive to the formation of precipitation.（ 3） By the influence of ＂Silk Road＂teleconnection from August 1 st to 2 nd pentad,Rossby waves originated from the North Atlantic along the westerly jet stream waveguide dispersed to East Asia-Pacific region,enhanced two height anomaly centers at middle and high latitude of the negative phase of EAP/PJ teleconnection,which played an important role in the maintenance and development of its morphology,and prompted the abnormal development of the WPSH to the peak period.（ 4） The high SST anomaly in the warm pool of the Western Pacific is the main rea
出处
《高原气象》
CSCD
北大核心
2017年第6期1595-1607,共13页
Plateau Meteorology
基金
国家自然科学基金项目(41275091)
关键词
长江中下游地区
夏季高温干旱
遥相关型
Rossby波作用量
Middle and lower reaches of Yangtze River Basin
summer drought and heat wave
teleconnectionpatterns
rossby wave action
