东亚寒潮高压的位涡诊断研究

A DIAGNOSTIC STUDY OF BUDGET OF POTENTIAL VORTICITY FOR COLD WAVE-RELATED ANTICYCLONE IN EAST ASIA

用位势涡度方程对１９８０年１月２６－３０日东亚寒潮高压的演变做了诊断研究，表明高压中心地区低层是低值位涡区，位涡值随高压增强（减弱）而变小（变大）；随着高压的发展加强，位涡最小值由对流层中层降到近地面层，随着高压的减弱，最小值中心又上升；对流层高层的位涡值随着地面高压的增强而加大，反映高空冷槽、地面高压同时在发展。位涡收支方程各项对高压发展、减弱有着不同的作用。作用最大的是地转风水平平流项和地转偏差风的散度项，其次是地转偏差风的平流项和辐射项，扭转项和热成风偏差项均甚小，可忽略不计。

A diagnostic study is made of a cold wave-related anticyclone in East Asia,for 26-30 January 1980,by using the potential vorticity equations. The results show that atthe initiation stage in the vicinity of anticyclonic centre there is a low potential vorticityarea where it decreases(increases)with the intensification(descension)of the high;when the high developing it descends from the middle troposphere to the nearer groundlayer,when the high decaying it ascends from the lower troposphere;while the poten-tial vorticity in upper troposphere increases with the intensification of surface high. The various terms in the potential vorticity equations have made very different con-tributions to the evolution of the anticyclone. The first contribution comes from thegeostrophic advection of potential vorticity and the divergence term of geostrophic devia-tion wind.The secondary are the advection of geostrophic deviation wind and radiationheating(cooling).The twisting term and thermal wind term could be ignored.