摘要
An analysis of the Ishii ocean heat content(OHC) in the tropical Indian Ocean from the surface to 700-m depth shows that the OHC changes dramatically on the interannual timescale in the Indian Ocean.The first mode of empirical orthogonal function(EOF1) of the OHC shows that there is a strong air-sea interaction pattern in the Indian Ocean with a positive(negative) loading in the east and a negative(positive) loading in the west.This seesaw oscillation pattern influences the summer precipitation in China with a North-South reversed distribution.Composite analysis shows that during a positive(negative) OHC episode,an anomalous cyclonic(anticyclonic) circulation over the western Pacific and South China weakens(enhances) the monsoonal northward flow in the lower troposphere;meanwhile,anomalous meridional circulation connects the descending(ascending) branch over the Southeast Indian Ocean and the ascending(descending) branch in South China as well as a descending(ascending) branch over North China.Analysis of the mechanism behind these features suggests that(1) the accumulation of OHC-induced vorticity is related to the wave activity over the mid-latitudes and that(2) the meridional teleconnection induced by the Indo-Pacific air-OHC interaction appears over East Asia and the western Pacific.Both of these patterns can cause summer precipitation anomalies in China.
An analysis of the Ishii ocean heat content （OHC） in the tropical Indian Ocean from the surface to 700-m depth shows that the OHC changes dramatically on the interannual timescale in the Indian Ocean. The first mode of empirical orthogonal function （EOF1） of the OHC shows that there is a strong air-sea interaction pat- tern in the Indian Ocean with a positive （negative） loading in the east and a negative （positive） loading in the west. This seesaw oscillation pattern influences the summer precipitation in China with a North-South reversed distri- bution. Composite analysis shows that during a positive （negative） OHC episode, an anomalous cyclonic （anti- cyclonic） circulation over the western Pacific and South China weakens （enhances） the monsoonal northward flow in the lower troposphere; meanwhile, anomalous merid- ional circulation connects the descending （ascending） branch over the Southeast Indian Ocean and the ascending （descending） branch in South China as well as a descend- ing （ascending） branch over North China. Analysis of the mechanism behind these features suggests that （1） the accumulation of OHC-induced vorticity is related to the wave activity over the mid-latitudes and that （2） the me- ridional teleconnection induced by the Indo-Pacific air-OHC interaction appears over East Asia and the west- ern Pacific. Both of these patterns can cause summer pre- cipitation anomalies in China.
基金
supported by the National Basic Research Program of China(973 Program):The impact of Southern Ocean-Indian Ocean air-sea processes on East Asia and the global climate change(Grant No.2010CB950300)
National Foundation of the Indian Ocean Opening Voyage Project(Grant Nos. 41149903 and 41049908)
the Knowledge Innovation Project for Distinguished Young Scholar of the Chinese Academy of Sciences (Grant No.KZCX2-EW-QN203)
the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX2-YWQ11-02)
the National Natural Science Foundation of China (Grant No.40906010)
