Annual pressure oscillation from sea level to I00 mb in the northern hemisphere

Abstract

From climatological normals of about 250 upper air observatories in the northern hemisphere, the annual mean, the annual oscillation and the semi-annual oscillation in the geopotential height of 850, 700, 500, 300, 200 and 100 mb pressure levels have been worked out; while the features of semi-annual oscillation are discussed elsewhere (Asnani and Verma 1975). The characteristics of annual mean, and annual oscillation are presented here. At long and above 700 mb level the maximum occurs first at the polar latitudes and then at sub-tropical latitudes with a lag 300 of about 3 to 4 weeks. At and south of won the amplitude is maximum at 200-mb level; at higher latitudes, the amplitude increases upto 100-mb level, the last level of our analysis.

           The annual mean picture as well as the annual oscillation exhibit some special features over the Asian region.