On the relationship between the winter Eurasian teleconnection pattern and the following summer precipitation over China

Abstract

The Eurasian teleconnection pattern (EU) is an important low-frequency pattern with well-known impacts on climate anomalies in Eurasia. The difference of low-level v-winds in several regions in the Eurasian mid–high latitudes is defined as the EU index (EUIV). In this study, the relationship between the winter EUIV and precipitation in the following summer over China is investigated. Results show that there is a significant positive (negative) correlation between the winter EUIV and the following summer precipitation over North China (the Yangtze River–Huaihe River basins). Meanwhile, an interdecadal variability exists in the interannual relationship, and the correlation has become significantly enhanced since the early 1980s. Thus, the proposed EUIV may have implications for the prediction of summer precipitation anomalies over China. In positive winter EUIV years, three cyclonic circulation anomalies are observed—over the Ural Mountains, the Okhotsk Sea, and the subtropical western North Pacific. That is, the Ural blocking and Okhotsk blocking are inactive, zonal circulation prevails in the mid–high latitudes, and the western Pacific subtropical high tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China, and significant positive (negative) precipitation anomalies over North China (the Yangtze River–Huaihe River basins), and vice versa. Further examination shows that the SST anomalies over the Northwest Pacific and subtropical central North Pacific may both contribute to the formation of EUIV-related circulation anomalies over the western North Pacific.