The three-dimensional distribution of atmospheric heating during the GWE
SCHAACK, TODD K.
JOHNSON, DONALD R.
- Publisher: Co-Action Publishing
The three-dimensional global distributions of time-averaged atmospheric heating for January, April, July and October 1979 are estimated from the ECMWF GWE Level IIIb data set. Heating rates are calculated through a vertical integration of the isentropic equation of mass continuity. Estimates of the vertical variation of heating are presented in isobaric coordinates through interpolation of the vertical profiles of heating from isentropic to isobaric coordinates. The horizontal distributions of heating and vertical profiles from various climatological regimes of the planetary circulation provide insight into the four-dimensional structure of the thermal forcing of the atmosphere. The large-scale structure of the heating distributions appears spatially and temporally consistent with known features of the global circulation and the seasonal evolution. Major features of the global distributions include the heating in regions of deep moist convection over South America, equatorial Africa, the ITCZ, the Asian monsoon circulation and the oceanic cyclone tracks of the Northern Hemisphere. The primary centres of heating migrate meridionally and zonally with changing seasons. The meridional migration is linked directly with the annual variation of the latitude of maximum incoming solar radiation. The zonal migration is linked with the planetary scale distribution of continents and oceans and the land-sea surface temperature distribution as determined by the surface energy balance and energy transport within the atmosphere itself. Throughout the tropical-subtropical regions, the strongest heating occurs above 600 mb in association with deep convection. Within the primary centres of heating associated with the Asian monsoon circulation, the maximum heating in the vertical profile is near 400 mb. Over the oceanic storm tracks of the Northern Hemisphere, heating occurs through most of the troposphere. The lower tropospheric heating is maximized in January and in that month is significantly stronger than the heating in the middle troposphere. In July there is negligible heating in the lower troposphere. Profiles from the high latitude continental regions such as central Asia and Canada are in close agreement showing cooling through most of the troposphere in winter and modest heating in summer. Profiles from desert regions over the Sahara and western Australia are also in close agreement showing a transition from low level heating to middle and upper level cooling. Cooling occurs throughout the free troposphere in regions of subtropical anticyclonic circulations over the eastern North and South Pacific Oceans.DOI: 10.1034/j.1600-0870.1990.t01-1-00001.x