A COMPARISON OF THE ROSSBY WAVE ACTIVITIES AND CIRCULATION FEATURES OF THE DROUGHT IN WINTER-SPRING OF 2011 AND IN SUMMER OF 2013 OVER MID-LOWER REACHES OF THE YANGTZE RIVER BASIN
XU Jin-ping
WANG Wen
CAI Xiao-jun
XU Zhi-li
XU Jin-xing
Abstract：Using the daily NCEP/NCAR reanalysis dataset and monthly OISST sea surface temperature data from 1981-2013,the formation mechanism of drought eventsin winter-spring 2011 and summer 2013 in the middle and lower reaches of the Yangtze River Region (MLRYR) is investigated.The results show that both the drought events have the following common points:(1) they were both affected by a strong East Asian monsoon,so the cold and warm air could not converge in the Yangtze River Basin,resulting in the lack of precipitation for this region;(2) the equatorial Pacific SST showed a pattern of "positive in the west versus negative in the east",which strengthened the Walker circulation and caused local Hadley circulation anomalies at the same time,making the MLRYR controlled by abnormal sinking airflow for a long time and the conditions insufficient for producing precipitation;(3) both the events were associated with Rossby waves from the Atlantic ocean.Influenced by NAULEA teleconnection pattern,Rossby wave energy propagated eastward to the east of Eurasian and Pacific region,an East Asia trough maintained in the vicinity of 120 °E for a long time,which strengthened the East Asian winter monsoon and further affected the precipitation of MLRYR in the winter-spring of 2011.With the mutual influence of the negative phases by teleconnections of Silk Road and EAP,the Rossby wave energy accumulated in the eastern Eurasian continent and the Pacific,resulting in WPSH extending abnormally westward,which strengthened the East Asian summer monsoon and further affected the precipitation of MLRYR in summer of 2013.
Keywords：mid-lower reaches of the Yangtze River BasindroughtRossby wavesteleconnection
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：8( 992-999 )