1977年1月500mb的大气环流及动能转换关系

1977年1月是北半球中纬大陆地区近年来最严寒的一个月。利用500 mb逐日资料,进行了天气学和能量学的研究,所得结果如下: (1)这个月极区经常出现高压,而且阿拉斯加高压脊特别强而稳定。由于极区高压,高纬西风动量大量地往中纬输送,造成高纬强东风。 (2)对于这个月月平均基本气流,进行正压不稳定度判据的检定,发现存在接近正压不稳定的条件。同时,有供给涡动发展的能量。 (3)这个月涡动中,最活跃的是n=3波,寒潮爆发主要是同3波盛行期相联系。3波之所以异常活跃,是由于从2波接受异常多的能量。 (4)2波输出能量较往年多一倍以上,主要输送给3波,对3波发展起着重要作用。 对这些结果进行了物理上的联系和讨论。

ON THE GENERAL CIRCULATION AND BAROTROPIC ENERGETICS AT 500 MB LEAVEL DURING JANUARY 1977

January 1977 was unusual cold throughout the mid-latitude continental region in the Northern Hemisphere. By using 500 mb level daily data of the January, the general circulation and barotropic energetics were investigated. Based on the study of 500 mb level circulation, it was pointed out that the cold January might be related to the following aspects:(1)There was often a high pressure over the polar cap, and the ridge in Alaska was very strong and steady. (2) The u-momentum transport from high latitudes to middle latitudes for the January was so abnormally large that anomalous east wind occured in high latitudes. (3) The monthly averaged basic air current was approximately the barotropic instable condition which was measured by the meridional gradient of absolute vorticity. The nonlinear wave-zonal and wave-wave exchanges of kinetic energy for the January was measured over the latitude belt from 17.5°N to 77.5°N.The monthly averaged values of these quantities were compared with the normal ones. According to the analysis of barotropic energetics it was shown that the severe cold January might be related to the following aspects: (1)n=3 wave kinetic energy was excessively strong. (2) The outbreak of severe cold wave was most closely associated with 3 wave development. (3) Wave of wave number 3 received much more energy from n=2 wave through wave-wave interaction. (4) The mag-nitude of energy transporting from n=2 wave to all other waves for the January was about twice as much as the normal one. The interrelationship of the above phenomena was discussed.