基于美国国家大气研究中心(NCAR)开发的通用地球系统模式(CESM),本文设计了nudging次表层海温的同化方案,进行了后报实验。对1982-2011年后报结果的分析表明,通过nudging同化,模式对ENSO现象有一定的模拟和预报能力,对赤道太平洋SST、纬向风、降水等海洋、大气要素等的后报结果与GODAS和NCEP再分析资料较接近,可以较好地重现历次厄尔尼诺和拉尼娜事件中异常东传的过程,超前1、3、6个月时,模式预报的Nio3指数与CPC指数的相关性分别达到0.88、0.81、0.70。但模式同时也表现出一定的春季预报障碍,秋季起报的后报效果最好,春季最差。对1982/1983和1997/1999两个厄尔尼诺事件的分析表明,模式后报的纬向风、热通量、风应力等大气变量的响应较实际滞后,而海洋的变化与实际情况相似,这与我们的同化方案设置有关,即模式只同化了次表层海温,进而强迫大气的响应,从而导致大气的变化较滞后。
An ENSO forecast system based on the Community Earth System Model (CESM) released by the Nation- al Center for Atmospheric Research (NCAR) is developed. We use a simple sub-surface sea temperature nudging scheme to generate realistic SST distribution. Hindcast results for the period 1982--2011 show a high predictabili- ty of ENSO. All past El Niflo and La Nifia events,including the strong 1997/1998 warm episode, are successfully predicted with SST, zonal wind and precipitation matching well with GODAS and NCEP datasets. The correlation coefficient of Niflo3 index scores 0. 88,0.81 and 0. 70 at the 1-, 3-and 6-month lead time respectively. However, the model shows a "spring prediction barrier" with the best predictability in autumn and the worst in spring. The com- parisons of zonal wind,heat flux, SST anomaly, wind stress and sub-surface temperature of 1982/1983 and 1997/ 1999 demonstrate that the atmospheric response is latter than that of the ocean, which is in contrast with observing and reanalysis data. This is due to the ocean-only data assimilation scheme, which forces a delayed atmospheric re- sponse.