The interannual relationship between anomalous precipitation over southern China and the south eastern tropical Indian Ocean sea surface temperature anomalies during boreal summer

Abstract

AbstractThe relationship between anomalous precipitation in the Guangxi Autonomous Region and Guangdong Province (GG) and sea surface temperature anomalies (SSTA) over the south eastern tropical Indian Ocean (SETIO) during the boreal summer is investigated using observational data, reanalysis data and the atmospheric linear baroclinic model. It is demonstrated that the anomalous precipitation in GG (PGG) has a significantly negative correlation with the SSTA in SETIO. The warm SSTA in SETIO could induce below normal PGG in at least three ways. First, the warming over SETIO can cause two cyclonic circulations along the tropical Indian Ocean and easterlies from the tropical central Pacific though Matsuno‐Gill responses. The easterlies have the advantage of maintaining the anomalous negative vorticity in GG. Second, the water vapour diverges from SETIO and converges in GG. Finally, the anomalous ascent motion in SETIO is enhanced, which favours the strengthening of the anomalous local Hadley circulation over East Asia. The anomalous local Hadley circulation causes the anomalous descent motion in GG. All these anomalous circulations could favour below normal rainfall in GG and vice versa. This suggests the SSTA over SETIO could be a monitor of PGG.