Decadal Changes of Meiyu Rainfall Around 1991 and Its Relationship with Two Types of ENSO

Thursday, 18 December 2014
Jian Zhu1, Danqing Huang2, Yaocun Zhang2, Anning Huang2, Xueyuan Kuang2 and Ying Huang2, (1)Hohai University, Nanjing, China, (2)Nanjing University, Nanjing, China
Meiyu rainfall over Yangtze-Huaihe River valley (YHRV) is revealed to have a decadal change around 1991 with a seesaw-like distribution. This decadal change is closely associated with negative phase of preceding winter El Niño-Southern Oscillation (ENSO) Modoki (EM) in the pre-1991 epoch and positive phase of conventional ENSO (CE) in the post-1991 epoch. In the pre-1991 epoch, due to enhanced precipitation, solar radiation decreases, resulting in SST cooling over western North Pacific in Meiyu period. An anomalous anticyclone associated with the SST cooling suppresses precipitation over northern part of YHRV. Meanwhile, an anomalous cyclone accompanied with the anticyclone locates over East China Sea and brings more precipitation to the southern part of YHRV. In the post-1991 epoch, the persistent simultaneous warming in eastern equatorial Pacific and Indian Ocean leads to abundant moisture brought to southern China.