MEAN MERIDIONAL CIRCULATION AND ANGULAR MOMENTUM BALANCE IN THE YEAR OF 1950

Utiliziug the latitudinal mean of upper meridional wind of 1950 given by Buchrs5 and Stan and White6,mean meridional circulation has been studied.Fig.1-3 (fig.1 for whole year,fig.2 for winter,fig.3 for summer) reveal three cells:two direct cells in low and high latitudes respectively and one indirect cell in middle latitudes.The average jet straam of 1950 is situated in the middle cell.The yearly average equatorial convergence zone is at about 50°N.From winter to summer all the three cells shift northward.The Hadley cell of winter hemisphere extends to summer hemisphere.The intensity of these cells seems to be stronger in winter than in summer.Angular momentum balance for the latitudes 10°N-70°N for the year 1950 was also studied,and figure for stream lines for the transfer of angular momentum was constructed (fig.5).The most interesting feature in this figure is that through the surface separating easterlies and westerlies the stream lines are vertical.Thus it indicates that the angular momentum generated in the easterlies is transported to the westerlies not in horizontal direction,but transported to upper westerlies in low latity.ides by vertical motion.Then from there it is tzansfered to middle latitudes.The mechanism of such transfer is as follows:In Hadley cell the upward motion in equatorial region and southern tropics carries more angular momentum due to earth's rotation,while the downward motion in northern tropics and subtropics carries less angular momentarn due to earth's rotation.Thus in the mean angular momentum generated in easterlies is transported to upper levels.Finally the mechanism of maintenance of zonal circulation was discussed.conclusion is this:In middle arid high latitudes gross disturbances ate of primary importance while in low latitudes mean meridional cirulation is important in maintaining zonal circulation.