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  • Author or Editor: William R. Kuhn x
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Frank Haurwitz
William R. Kuhn


The planetary radiation for the Southern Hemisphere troposphere has been calculated from climatological data for January and July. Zonally averaged profiles of cooling/heating rates are presented. In addition, calculations have been made for selected latitudes and longitudes to illustrate the variation from the mean zonal rates. The outgoing planetary radiation and the zonally averaged net flux divergence are also discussed.

The heating/cooling rate calculations show that maximum cooling occurs in the mid-troposphere and is larger over the oceans than the continents, with longitudinal variations reaching 1C day−1. Results are similar to those of Katayama for the Northern Hemisphere with the exception that we find significant heating at the base of the cirrus clouds.

The hemispheric distribution of outgoing flux agrees qualitatively with that derived from satellite measurements. The annual longitudinally averaged results agree closely with those of Sasamori et al. except in the vicinity of the polar front where our outgoing fluxes are about 25 ly day−1 smaller while in the polar latitudes our results are larger by a comparable amount. Many of the variations are directly attributable to cloud cover and the need for additional cloud data is exphasized.

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C. Bruce Baker
William R. Kuhn
, and
Edward Ryznar


Direct normal and diffuse solar irradiances and 500 nm aerosol optical depths measured at the University of Michigan departed far from normal on 26 October 1982, when it is concluded that the main stratospheric cloud from the El Chichon volcanic eruption arrived at the 42°N latitude of the radiation measurement facility. For clear-sky data analyzed through 19 January 1983, direct solar is about 25% less than normal and diffuse solar is about 85% greater. For the same aerosol optical depths and solar zenith angles, the ratio of diffuse to direct is about 30% greater for about 0.3 cm of precipitable water but nearly the same for 0.9 cm. Aerosol optical depths are nearly three times greater for wind directions that naturally advect the cleanest air. The effect of circumsolar irradiance on the methods used to measure direct normal and diffuse irradiances cause the former to be overestimated and the latter to be underestimated.

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