Preliminary Analysis Of Pacific Ssta And Winter Northern Hemisphere Atmospheric Circulation Anomalies Relations

The relationship between sea surface temperature anomaly in Pacific and the circulation of Northern Hemisphere is the focus of air-sea interaction research in recent years. The SSTA in Pacific contributes to Remote Response in mid-latitude atmosphere, and is connected with climate changes in global. The cycling of ENSO is typical phenomena of large scale in Pacific air-sea interaction system.Results of recent observation and numerical experiments show that prominent difference exists between air-sea interaction in tropical and in mid-latitude, and work is not enough related to the impact of persistent SSTA on the circulation considering different district in Pacific. By use of NOAA SST and atmosphere circulation datasets, the relation between SSTA in Pacific and anomaly in circulation is studied.Various statistical research reveals that there is significant correlation between North Hemisphere Circulation and SSTA in West Wind Drift region, as well as in tropical eastern Pacific, which are the two key regions in Pacific. The frequency analysis of area-averaged SSTA time series in key regions indicates that the power spectrum peaks is centered at 2-4yr annual oscillation, and there is also long temporal scale oscillation such as quasi decadal oscillation revealed by Wavelet Analysis. Singular Value Decomposition (SVD) analysis shows significant correlation exists between Pacific SSTA pattern similar to peak-mature phase of El Nino event and Remote Response Pattern of PNA and WP in 500 hPa geopotential height, which is further confirmed by SVD analysis between SSTA and 850 hPa wind fields.On base of results above, composite model of SSTA in Pacific and circulation anomaly are constructed for analysis their evolution. During mature phase of El Nino usually in winter, positive SSTA dominates in tropical eastern ocean and negative SSTA dominates in West Wind Drift District in mid-latitude ocean, correspondingly the PNA index of 500 hPa geopotential height is positive which means the Aleutian Low gets strong, and the situation is somewhat inversely during La Nina phase of SSTA. Numerical experiments are set up for analysis impact of SSTA in two key regions on atmosphere circulation.Under perpetual winter condition IAP R15L9 AGCM is set up for sensitive experiments of Pacific SSTA without seasonal variability. The circulation of positive PNA index pattern is prominent in the case of persistent forcing of negative SSTA in West Wind Drift region or positive SSTA in tropical eastern Pacific, which is the typical SSTA Pattern during El Nino peak-mature phase. And the results is somewhat inversely forced by SSTA of opposite sign in distribution.