IMPACT OF ENSO ON THE PRECIPITATION OVER CHINA IN WINTER HALF YEAR
LI Tian-ran
ZHANG Ren-he
WEN Min
Abstract：The impact of ENSO on the precipitation over China in winter half year is investigated by using observed and reanalysis datasets in 1979-2010.The results show that positive precipitation anomalies with statistical significance appear over southern China in El Ni(n)o episodes,which are caused by the enhanced warm and humid southwesterliesalong the East Asian coast in the lower troposphere.The enhanced southwesterlies transport more water vapor to southern China,and the convergence of water vapor over southern China increases the precipitable water and specific humidity in the atmosphere.In La Ni (n)a episodes,no reverse precipitation anomalies with statistical significance appear over southem China.Although atmospheric elements are changed reversely,they are not statistically significant as those in El Ni (n)o periods.The possible physical mechanism of the asymmetric impact of ENSO cycles on the precipitation over southern China is investigated by analyzing the intraseasonal oscillations (ISOs) in El Ni(n)o and La Ni (n)a,respectively,in winter half year.By comparing the characteristics of ISOs in El Ni(n)o and La Ni(n)a,a physical mechanism is proposed to explain the asymmetric responses of the precipitation over China toENSOin winter half year.In El Ni(n)o episodes,over westem North Pacific (WNP) and South China Sea (SCS)the ISOs are inactive and exert little effect on the water vapor transport and convergence,inducing the positive precipitation anomalies with statistical significance over southern China in El Ni(n)o episodes.In La Ni(n)a episodes,however,the ISOs are active,which weaken the interannual variation signals of ENSO over WNP and southern China and lead to the insignificance of the interannual signals related to ENSO.Therefore,the asymmetric responses of precipitation over China to ENSO in winter half yearare possibly caused by the difference of intraseasonal oscillations over WNP and SCS between El Ni(n)o and La Ni(n)a.
Keywords：climatecharacteristics of precipitation over ChinaENSOintraseasonal oscillationwinter half
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：10( 1-10 )