Abstract
The interdecadal change in the relationship between the East Asia-Pacific (EAP) teleconnection pattern and rainfall over East China during boreal summer (June–August) was investigated using observation and reanalysis datasets during 1951–2018. As proposed in a previous study, summer rainfall in the Yangtze-Huaihe River (YH-R) valley is below (above) normal when a positive (negative) EAP event occurs. Based on the close relationship with the rainfall anomalies, the EAP teleconnection pattern has been widely used in the prediction of summer rainfall variations in the YH-R valley. However, we found that the rainfall anomalies in the YH-R basin associated with the EAP pattern were weaker and less evident after the late 1980s. This finding indicates a decreased relationship between the EAP pattern and YH-R basin summer rainfall after the late 1980s, and a decrease in the quality and skill of seasonal predictions of YH-R basin summer rainfall related to the EAP pattern. This pronounced weakening in the YH-R summer rainfall-EAP pattern connection is attributed to the northeastward displacement of the Japanese action center of the EAP pattern after the late 1980s, which caused weaker anomalous vertical motion and moisture transportation over the YH-R valley. The present research reveals that the interdecadal expansion in the size of the Indo-Pacific warm pool in the late 1980s is likely responsible for the northeastward shift in the Japanese action center of the EAP teleconnection pattern by modulating anomalous convective activities and the northward propagation of the EAP pattern.
Highlights
The present analysis reveals that the and the East Asia-Pacific (EAP) teleconnection pattern experienced an obvious interdecadal shift in the late weakening relationship between the EAP pattern and the Yangtze-Huaihe River (YH-R) basin summer rainfall
Before the late 1980s, the summer rainfall in the YH-R valley tended to be less than resulted from the notable northeastward displacement of the Japanese action center of normal during positive EAP years, whereas after the late 1980s, the rainfall–EAP pattern the EAP pattern after the late 1980s
Compared with the first subperiod, in which the Japanese action center was located along the conventional Meiyu band stretching from the YH-R valley to the area south of Japan, this action center had an obvious northeastward shift in the second subperiod, with vorticity anomalies confined around Japan
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Over East China, the summer (June–August (JJA)) rainfall anomaly is an important climate change variable that causes severe droughts and floods [1]. The catastrophic flood that occurred in the Yangtze River valley in the summer of 1998 resulted in immense damage to the local economy, society, and people’s lives [2]. It is important to improve the understanding of summer rainfall variability over East China, which may contribute to reductions in damage and losses caused by anomalous droughts and floods
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