The Uniqueness Of Oceanic Processes Near California And Their Possible Effects On PDO Short Cycles

This study explores the characteristics of interannual and(inter)decadal air-sea interaction related to Pacific Decadal Oscillation(PDO)over the different regions of the North Pacific based on the relationship between turbulent heat flux anomalies and sea surface temperature(SST)anomalies during 1958-2018.On the interannual scale,the atmosphere drives directly SST anomalies over the Kuroshio-Oyashio Extension(KOE),it is mainly the abnormal wind speed in the atmosphere that controls the turbulent heat flux,which may force the SST anomalies.The SST anomalies,which may be determined by the internal dynamic processes of ocean,force atmosphere circulation over the equatorial central and eastern Pacific.On the(inter)decadal scale,it shows SST anomalies are mainly drived by atmospheric circulation over the north center of PDO.But ocean is very important in forming SSTAs off California coast,and this phenomenon exists in both DJF and JJA.Further analysis shows that the SST period off California coast is about 12 years,and the area off California coast is one of the key areas of quasi-12 a oscillation of PDO.The upwelling of the equatorial central Pacific and the meridional wind stress anomalies in the subtropical eastern North Pacific are the other two important parts in the quasi-12 a oscillation of PDO.The cold(warm)SST off California coast may correspond to the anticyclone(cyclone)circulation above it,with the northeastly(southwestly)anomalies in the subtropical eastern North Pacific,and significant easterly(westerly)anomalies in the central North Pacific and the central equatorial Pacific.These wind stress anomalies maybe caused by the cold(warm)SST off California coast,is superimposed on the climatology wind,which could cause cold(warm)SST anomalies in the subtropical eastern North Pacific and warm(cold)SST anomalies in the central North Pacific.Meanwhile,the anomalous warm(cold)water in the western equatorial Pacific moving eastward along the thermocline and upwelling in the central equatorial Pacific are accompanied.