On The Diagnosis Of The Influence Of Different SST Patterns On The Winter Air Temperature Of China

By using the monthly mean data at 160 observational stations of China and NCAR/NCEP reanalysis data, the generalized equilibrium feedback assessment (GEFA) method, combined with the methods of EOF analysis, correlation analysis and composite analysis are used to explore the different influence of SST on the cold-northeast/warm-southwest pattern (CNE-WSN) of the winter temperature in 2009/2010 and other typical years, and its possible mechanism. The main conclusions are the following:(1)According to the analysis of stability and sensitivity of the feedback factor B to the main ocean variability modes (CNE-WSN pattern), it is found that B is stable when the sample is longer than 96 months, and not sensitive to the sample selection.(2)The 2009/2010 winter air temperature oscillation mode between northern and southern parts of China is closely related to the corresponding sea surface temperature anomalies (SSTA) and its related atmospheric circulation anomalies. The above-mentioned air temperature mode, exhibiting a warming in Northeast China and a cooling in Southwest China, is significantly forced by the El Nino mode and the North Atlantic SSTA mode, which has three poles. Under the influence of SSTA modes, the ground northerly flow transported cold air to north and northeast China, resulting in low temperatures in the region. Meanwhile, the mid-latitude westerlies are intensified, and the polar cold air had been entrenched in high latitude and cannot affect the Southwest, resulting in the warming of the Southwest.(3) According to the analysis of the temperatures of China in 1965/1966 and 2000/2001 (CNE-WSN positive phase years), it is found that the 1965/1966 winter temperature anomaly is significantly influenced by the equatorial middle-east Pacific El Nino mode, warm tropical northwest Indian ocean mode, and cool south Indian ocean mode.2000/2001 winter temperature anomaly is significantly forced by the warm high latitude north Pacific SST mode, cold tropical-subtropical western Pacific mode, and the north Pacific warm-west/cold-east mode. Under the influence of SSTAs, the deepened East Asian trough is conducive to cold air, and the strengthened subtropical high brings warmth to the southwest.(4) According to the analysis of 1988/1989 and 2007/2008 (CNE-WSN positive phase years), it is found that 1988/1989 and 2007/2008 winter temperature anomaly is significantly forced by the equatorial middle-east Pacific La Nina mode and the tropical Pacific east-warm/west-cold mode. The atmospheric circulation anomalies in the positive and negative phase years of CNE-WSN are almost opposite to each other, but they are all accompanied by the Asian trough weakening. The weakened East Asian trough prevents the cold air from influencing the northern region.(5)The analysis shows the contribution of sea surface temperature mode depends not only on the size of the response coefficient, but is also related to the intensity of the SST anomalies. CNE-WSN positive phase years are forced by different main SST modes, but the negative phase years are forced by the La Nina mode.