Residual Circulations Calculated from Satellite Data: Their Relations to Observed Temperature and Ozone Distributions

Abstract

Monthly mean residual circulations were calculated from eight years of satellite data. The diabatic circulation is usually found to give a good approximation to the residual circulation, but this is not always the case. In particular, an example is shown at 60°S and 30 mb where the diabatic and residual circulations show very different annual variations. Correlations between the vertical component of the residual circulation and temperature and ozone were computed. They indicate that yearly variations of temperatures in the tropics are under dynamical control while at higher latitudes they are under radiative control, except during stratospheric warmings. Interannual variations in seasonal mean temperatures are shown to be under dynamical control everywhere. Correlations between the interannual variations in the seasonal means of the vertical component of the residual circulation and ozone mixing ratios are consistent with what would be expected from the ozone variations being due to differences in the ozone transport, although transport effects cannot easily be distinguished from photochemical effects above the altitude of the ozone mixing ratio peak. Finally, variations in total ozone are examined in comparison with residual circulations variations. A one to two month phase lag is seen in the annual variation in the total ozone at 60°N with respect to the maximum downward residual motions. This phase lag is greater at 60°N than at 60°S. There is evidence at 60°S of a greater downward trend in the mean zonal ozone maxima than there is in the minima. A decreasing trend in the maximum descending motion is seen to accompany the ozone trend at 60°S.