Tropospheric temperatures and Southern Hemisphere circulation

This note documents improvements in the Southern Hemisphere midlatitude circulation associated with a revised convective scheme that was implemented in a version of the NCAR Community Climate Model. Perpetual July and January runs are performed for a standard control and an experiment with a revised convective parameterization. The most notable result is a warmer troposphere at all latitudes that is closer to the observed than to the control. Since the warming is greatest in the tropics, the equator-to-pole temperature gradient is increased in both July and January. As a consequence, the midlatitude u wind maximum is stronger at both times of the year in the lower and mid-troposphere. Midlatitude eddy heat increases somewhat, but greatest changes are seen in large increases of poleward eddy momentum transport. -from Authors