冬季乌拉尔山月平均阻塞形势的统计分析和数值试验

根据冬季（１２，１，２月）乌拉尔山地区月平均阻塞形势集中出现的范围和强度定义了一个阻塞指数。相关分析表明：乌拉尔山月平均阻塞与中国月平均气温有较大的负相关关系；它和全球海表温度之间存在三个明显的高相关海区；北太平洋热带东部海区，北大西洋热带和中纬度海区以及阿留申群岛西南方的海区。应用两层原始方程谱模式，在以上３个海区上空加入理想的非绝热孤立热源强迫分别做数值试验。结果表明：３个海区上空的非绝热孤立

NUMERICAL EXPERIMENTS ON AND STATISTICAL ANALYSIS OF MONTHLY MEAN BLOCKING OVER THE URALS IN WINTER

The present paper has defined a blocking index in terms of the range and intensity of the monthly mean blocking over the Urals in winter(December, January and February). Correlation analysis indicates that monthly mean blocking over the Urals has a pretty large anticorrelation with the monthly mean temperature in China. Between the blocking index and the global SST there exist three Significant correlation regions.eastern part of the Northern tropic Pacific, Northern tropic Atlantic and midlatitute sea region,and the South-west Aleutians. Using the spectral model of a two-level primitive equation, numerical cxperiments have been conducted on the above-three sea regions after steady diabatic isolated heatsource forcings have been added. Results show that the heatsourceforcings in the three sea regions have an effect upon the Ural blocking through exciting the quasistationary Rossby wavetrain. The dynamic diagnosis of the numerical experiments indicates that the heatsource forcings have intensified the cut-off low in the upperstream and downstream doughs of the Ural blocking region ;and the LF enstrophy of tam and downstream doughs of the Ural blocking region; andthe LF enstrophy of the blocking region comes mainly from the interactions of the LF eddies themselves.