Relationship Between Soil Temperature in May over Northwest China and the East Asian Summer Monsoon Precipitation

This study investigates the relationship between the soil temperature in May and the East Asian summer monsoon (EASM) precipitation in June and July using station observed soil temperature data over Northwest China from 1971 to 2000. It is found that the memory of the soil temperature at 80-cm depth can persist for at least 2 months, and the soil temperature in May is closely linked to the EASM precipitation in June and July. When the soil temperature is warmer in May over Northwest China, less rainfall occurs over the Yangtze and Huaihe River valley but more rainfall occurs over South China in June and July. It is proposed that positive anomalous soil temperature in May over Northwest China corresponds to higher geopotential heights over the most parts of the mainland of East Asia, which tend to weaken the ensuing EASM. Moreover, in June and July, a cyclonic circulation anomaly occurs over Southeast China and Northwest Pacific and an anticyclonic anomaly appears in the Yangtze and Huaihe River valley at 850 hPa. All the above tend to suppress the precipitation in the Yangtze and Huaihe River valley. The results also indicate that the soil temperature in May over Northwest China is closely related to the East Asia/Pacific (EAP) teleconnection pattern, and it may be employed as a useful predictor for the East Asian summer monsoon rainfall.