SEASONAL VARIATIONS OF THE ANTARCTIC TROPOPAUSE

Computations of radiative cooling are made, and the conclusion is reached that the rate of cooling in the antarctic atmosphere is more than sufficient for the observed minimum temperatures to be attained in the lower stratosphere. In addition, the vertical distribution of radiative cooling is such as to give a positive lapse rate in the stratosphere and, ultimately, the disappearance of the tropopause. Synoptic data indicate that there may exist a tendency for a somewhat weaker meridional exchange of air in the winter season in the high latitudes of the southern hemisphere, as compared to the analogous exchange in the northern hemisphere. Insofar as a weaker meridional exchange will allow radiative cooling to operate more effectively in the antarctic, Court's explanation for the disappearance of the tropopause is accepted.