Local and Remote Factors Affecting the SST–Precipitation Relationship over the Western North Pacific during Summer

Abstract

he western North Pacific (WNP) monsoon variability plays an important role in East Asian climate, and it highlights the importance of understanding atmosphere?ocean interaction determining WNP variability. A key characteristic of atmosphere?ocean interaction is the local relationship between sea surface temperatures and precipitation (SST?P), which over the WNP exhibits a weak and negative correlation; this indicates that atmospheric variations lead to SST anomalies. This study investigates the underlying physical causes of this relationship, and it suggests that the inverse SST?P relationship over the WNP results from a local anomalous lower-tropospheric anticyclone or cyclone. A strong and negative SST?P correlation corresponds to a strong cyclonic/anticyclonic anomaly, while a weak SST?P relationship is related to a weak circulation anomaly. This study suggests that the remote effects play a crucial role in forming the inverse SST?P relationship over the WNP, while local SSTs tend to result in a positive SST?P correlation and partially offset the remote effects. Furthermore, the negative SST?P relationship over the WNP tends to be associated with rapid transitions of SST anomalies in the equatorial central and eastern Pacific, implying that atmosphere?ocean interaction over the WNP during summer may be affected by and in turn modify the evolution of ENSO.