西风急流对一次华南早春极端暴雨影响的分析  

Impact of the Subtropical Westerly Jet on a Heavy Rainstorm in Early Spring in Southern China

作　　者：李杨 孙即霖[1] 时晓曚 

机构地区：[1]中国海洋大学物理海洋实验室&海洋-大气相互作用与气候实验室,山东青岛266100 [2]青岛市气象局,山东青岛266003

出　　处：《海洋湖沼通报》2018年第1期18-26,共9页Transactions of Oceanology and Limnology

基　　金：国家自然科学基金(41276012);国家自然科学重点基金(41430963)资助

摘　　要：利用MICAPS站点降水数据和NCEP再分析资料对2014年3月30-31日发生在广东的一次极端降水过程进行了分析。结果表明,副热带北大西洋东部上空200hPa扰动在南支西风急流中的传播对本次极端降水的触发具有重要影响。降水发生前,副热带北大西洋东部高空不稳定槽发展,扰动信号进入南支西风急流并沿其向下游传播。阿拉伯海上空暖平流使印度上空的脊得到加强,脊前冷平流导致脊前位于华南上空的槽加深,从而导致降水区上空急流最大风速中心断裂,形成有利于极端降水发生的高层大气环流形势——急流入口区的右侧,涡度平流随高度增加和强的辐散中心引发强烈的上升运动,配合低层气旋式切变与充分的水汽供应,导致了此次极端降水的发生。An extreme heavy rainfall processed in southern China on 30 Match, 2014, is investigated using MICAPS rainfall data and NCEP reanalysis data. The results showed that the eastward propaga- tion of disturbance troughs originated from eastern subtropical north Atlantic at 200hPa within subtrop- ical westerly jet played a key role in this heavy rainstorm. The unstable troughs in upper level over eastern subtropical north Atlantic developed before the precipitation began, and this kind of disturbing signal propagated eastward within the subtropical westerly jet. Persistent warm advection over Arabian Sea intensified a ridge over India, and cold advection in front of this ridge deepened the trough over southern China. It caused interrupt of maximum wind speed center in jet over precipitation area, which was conducive to the formation of circulation pattern of extreme precipitation. The rainfall area was corresponded to the right side of the entrance region of the jet, where the vorticity advection increased with height and the center of divergence led to strong ascending motion, resulting in this extreme heavy rainfall cooperated with cyclonic shear of low level and abundant supply of water vapor.

关 键 词：副热带西风急流 华南早春暴雨 深厚对流 Rossby波导 

分 类 号：P44[天文地球—大气科学及气象学]