Interdecadal change of the relationship between the tropical Indian ocean dipole mode and the summer climate anomaly in China

The interdecadal change of the relationship between the tropical Indian Ocean dipole (IOD) mode and the summer climate anomaly in China is investigated by using monthly precipitation and temperature records at 210 stations in China and the NCEP/NCAR reanalysis data for 1957-2005. The results indicate that along with the interdecadal shift in the large-scale general circulation around the late 1970s, the relationship between the IOD mode and the summer climate anomaly in some regions of China has significantly changed. Before the late 1970s, a developing IOD event is associated with an enhanced East Asian summer monsoon, which tends to decrease summer precipitation and increase summer temperature in South China; while after the late 1970s, it is associated with a weakened East Asian summer monsoon, which tends to increase (decrease) precipitation and decrease (increase) temperature in the south (north) of the Yangtze River. During the next summer, following a positive IOD event, precipitation is increased in most of China before the late 1970s, while it is decreased (increased) south (north) of the Yangtze River after the late 1970s. There is no significant correlation between the IOD and surface air temperature anomaly in most of China in the next summer before the late 1970s; however, the IOD tends to increase the next summer temperature south of the Yellow River after the late 1970s.