Investigating air-sea interactions in the North Pacific on interannual timescales during boreal winter

Abstract

We study the air-sea interaction in a perspective of interannual timescale with wintertime observed sea surface temperature (SST), turbulent heat flux (THF) and sea level pressure (SLP) based on lead-lag correlation and regression. Being forced by the atmosphere, the ocean also has a response to the atmosphere, especially in the subarctic frontal zone (SAFZ) and the eastern North Pacific. The air-sea interactions in two regions are quite similar but associated with different patterns of atmospheric variability when SST leading SLP for one month. Since the SST changes in the eastern North Pacific and the equatorial east-central Pacific are synchronous in the dominant mode (EOF1) of the SST anomalies, the SLP responses to SST in the eastern North Pacific and central Pacific (CP) ENSO both show Pacific-North American (PNA) teleconnection pattern. The CP ENSO dominates the tropical influence on the air-sea interaction in the eastern North Pacific during November. Specifically, the response of Aleutian low to CP El Niño events leads to heat transport from ocean to atmosphere in the eastern North Pacific. In CP La Niña years, the air-sea heat exchange is affected by the combination of Aleutian low and lower troposphere westerlies.