The association between latitudinal temperature gradient and eddy transport Part III: the southern hemisphere

We describe the mean transfer of sensible heat in the transient eddies at 850 hPa, the mean 500 hPa temperature gradient for the years 1980-1988, and the three-month running means of their zonal averages. The flux intensified during the period and its peak drifted south by 5°lat. The 500 hPa meridional temperature gradients did not vary systematically in their subtropical winter peak, but their mid-latitude summer peak weakened somewhat. Correlations between the zonally averaged heat flux and the temperature gradients show that when the seasonal mean flux was strong in latitudes lower than 4008-45"8, the gradients tended to be steep in the subtropics and weak to the south, and conversely when the flux was weak. The same link between flux and gradients is observed in the northern hemisphere, where chiefly the heat flux in the quasi-stationary waves in winter is associated with the temperature gradients. The gradients (thermal winds) in higher and lower latitudes are therefore negatively correlated in both hemispheres. The quasi-stationary waves in the southern hemisphere carry almost no sensible heat poleward, and the transient eddy flux north of 45°S thus serves the same function through the year as does the total eddy heat flux -especially its stationary component -in the northern hemisphere during the colder part of the year.