扰动动能与平均动能转换率及其角动量涡旋输送与新疆暴风雪过程的关系

用1995年5月至1999年4月KWBC北半球500 hPa高度场5°×5°客观分析资料,应用谐波分析把等压面高度场沿纬圈作富利叶级数展开,计算逐日25°~80°N每隔5°纬度递增的沿纬圈的扰动动能与平均动能转换率(E)、角动量涡旋输送(RM),分析了E和RM的年、季分布特征及其与新疆暴风雪过程的关系.结果表明:E和RM具有显著的季节变化和周期性;E的正高值中心与新疆暴风雪过程有较好的关系,出现E正高值中心的日期作为预报指标日,其后3~6 d新疆将出现暴风雪天气过程,出现RM负低值中心的日期作为预报指标日,其后3~8 d新疆有暴风雪过程发生;当E的正高值中心和RM的负值中心同时出现时,更确定了新疆暴风雪过程出现的可能性.

The Conversion Rates of Perturbation Kinetic Energy into Mean Kinetic Energy and Angular Momentum Vortex Transferring in Relation to Snowstorm Processes in Xinjiang Region

Based on the 500 hPa height data of the Northern Hemisphere from 25° to 80° and from May 1995 to April 1999,the daily angular momentum vortex transferring data(RM) and the conversion rate(E)of perturbation kinetic energy into mean kinetic energy are calculated at an interval of five degrees of latitude.The relationship are studied between both the E and RM and the snowstorm weather process in Xinjiang Region.The result shows: E and RM have obvious cycles,seasonal variations and periodicity;the positive high value center of E and low value center of RM have good response to the snowstorm weather process in Xinjiang Region.At the same time the weather process will occur 3 to 6 days later in the region when the positive high value center or low value center appears and the day is regarded as an index date.The forecast accuracy of the snowstorm in Xinjiang Region will be raised when the positive high value center of E and the negative angular momentum vortex transfer center take place simultaneously.