Meridional heat transport by the atmosphere and the ocean: analysis of FGGE data

Abstract

The annual mean meridional heat transport by the atmosphere is evaluated by using FGGE (First GARP Global Experiment) level IIIb data. The transport by the atmosphere-ocean system is estimated using satellite radiation observations from the Nimbus 7 ERB (Earth Radiation Budget) experiment. The annual mean transport by the ocean is obtained as the difference between the two values. The latitudinal distribution of transport by the total system exhibits good symmetry between the two hemispheres, with maximum poleward transport of 5.9 × 10¹⁵ W around 35° latitude N and S. Atmospheric and oceanic contributions to the transport exhibit large differences between the two hemispheres. In particular, in the subtropics of the northern hemisphere, the ocean carries more heat poleward than in the same latitude of the southern hemisphere. The poleward transport by the ocean at20°–30°N evaluated in this study is about 3 × 10¹⁵ W, which is smaller by 0.5–1 × 10¹⁵ W than that found by Carissimo et al. but larger by 1–2 × 10¹⁵ W than recent estimates based on surface heat balance. The difference between the results of this study and Carissimo et al. comes from differences in estimates of the heat and moisture transport by mid-latitude atmospheric transient eddies.