NUMERICAL STUDY OF THE SHORT-TERM CLIMATIC OSCILLATION FORCED BY EL NINO DURING NORTHERN WINTER

<正> Using a nine-layer global spectral model, numerical schemes with two different SST distributions inJanuary (control case and abnormal case) have been tested to study the climatic effect, propagation charateris-tics and the maintenance mechanism of the short-term climatic oscillation caused by El Nino during northernwinter. The main results are as follows: (1) During northern winter, there exist two wave trains because ofthe influence of El Nino. One is similar to PNA pattern, and the other is similar to EUP pattern. (2) ThePNA-like wave train caused by the anomalous SST forcing in central and eastern equatorial Pacific Ocean is dueto the response of ultralong wave and long wave components of Rossby mode, and the EUP-like wave traincrossing Eurasia is mainly due to the wave component of Rossby mode. (3) During northern winter, the warmwater region in central equatorial Pacific Ocean is the source of forced wave trains. (4) In northern winter,the energy source for maintaining the short-term climatic oscillation is from the interaction between eddies, andbetween eddy and zonal flow.