On the Distribution of Mean Static Stability and Mean Richardson Number in Tropical Atmosphere

[摘要] Mean tropospheric soundings over different regions of the tropical belt lying between 30°Nand S during different periods of the year are constructed and used to compute mean staticstability (SS) over all regions and mean Richardson number (Ri) over monsoon regions in differentisobaric layers. The results show that the vertical distribution of moist static stability based onvalues of equivalent potential temperature is remarkably similar in all regions, with high negativevalues near surface and high positive values in the upper troposphere, the level of transition fromnegative to positive value occurring at a level between about 700 and 500mb. However, theinvestigation reveals the following regional and seasonal characteristics in values of mean staticstability: (a) in any particular region, the lower troposphere is statically more unstable andinstability extends to greater heights during the summer than during the winter; (b) during aparticular season, the regions lying in the summer hemisphere show greater static instabilityextending to greater heights than those lying in the winter hemisphere: and (c) in any particularhemisphere, the atmosphere over the region/area lying near the equator is statically more unstablethan that lying away from the equator.The vertical distribution of Ri as judged by values in monsoon regions appears to exhibitsimilar variation with seasons and between regions as static stability.

[学科分类] 大气科学