Interannual Time-Scale Relationship between Mongolia High and SST Anomaly in the North Pacific in Winter

The difference of sea level pressure (SLP) between the Mongolia high and the North Pacific has been regarded as an important reason to cause East Asian winter monsoon and its variation, but most of the interrelated studies are associated with interdecadal time scale. This study will reveal the relationship on interannual time scale between the Mongolia high and the sea surface temperature (SST) in the North Pacific in winter. The data analyses show that negative correlation between the Mongolia high and the Pacific Decadal Oscillation (PDO) is still evident on interannual time scale, and strong (weak) Mongolia high in winter is corresponding to negative (positive) phase of the PDO; interdecadal variation exists in this interannual negative correlation, and it generally appears in the period that the interdecadal correlation is not distinct. The data analyses also show that there is a high correlation belt between the winter Mongolia high index and the SST in the North Pacific from the northeastern Pacific to the tropical western Pacific, and both of its location and pattern are similar to the Interdecadal Pathway (IP) in the previous research. This correlation obviously exists in the period from the preceding spring to the corresponding winter, which demonstrates a fixed feature of the air－sea interaction in the Asia/North Pacific area, and it can be called air－sea interaction bridge (SAIB) in the middle latitudes of the North Pacific. It is also shown that the distribution of correlation coefficient expressing the SAIB varies with the season, which means that the interannual correlation of the air－sea interaction has seasonal variation characteristics. Since the SSTA mode is relatively stationary, the PDO and SST anomaly in the SAIB region could be the factor to predict the Mongolia high activity in winter (East Asian winter monsoon). Particularly in the earlier stage (especially in summer), positive SST anomaly in the SAIB region could have the indicative sense for the enhancement of Mongolia high (East-Asian monsoon) activity in winter.