RADIATION MODELS OF MIDLATITUDE SYNOPTIC FEATURES

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  • 1 Department of Meteorology, University of Wisconsin, Madison, Wis.
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Abstract

Balloon-borne radiation sonde measurements during 1964 and 1965 are used to form composite, three-dimensional radiative cooling models for the following midlatitude synoptic features: stationary front; nascent cyclone; warm sector cyclone; occluded cyclone; and anticyclone. Composite water vapor distributions for the same synoptic features are used to model the pattern of atmospheric warming by solar radiation.

Thickness tendency analyses of the 1000-500-mb layer for four synoptic features show that radiative cooling and warming may account for 10–30 percent of the observed maximum thickness tendency. The radiative thickness change components are of the same order of magnitude as the latent and the sensible heating terms.

The nascent cyclone case shows a radiatively induced vorticity tendency of 6 × 10−10 sec−2. This compares with a total expected vorticity tendency between 10−9 and 10−10 sec−2. The nascent cyclone, warm sector cyclone, and anticyclone cases show positive cyclonic development from radiative effects, while the occluded cyclone case shows negative cyclonic development.

Abstract

Balloon-borne radiation sonde measurements during 1964 and 1965 are used to form composite, three-dimensional radiative cooling models for the following midlatitude synoptic features: stationary front; nascent cyclone; warm sector cyclone; occluded cyclone; and anticyclone. Composite water vapor distributions for the same synoptic features are used to model the pattern of atmospheric warming by solar radiation.

Thickness tendency analyses of the 1000-500-mb layer for four synoptic features show that radiative cooling and warming may account for 10–30 percent of the observed maximum thickness tendency. The radiative thickness change components are of the same order of magnitude as the latent and the sensible heating terms.

The nascent cyclone case shows a radiatively induced vorticity tendency of 6 × 10−10 sec−2. This compares with a total expected vorticity tendency between 10−9 and 10−10 sec−2. The nascent cyclone, warm sector cyclone, and anticyclone cases show positive cyclonic development from radiative effects, while the occluded cyclone case shows negative cyclonic development.

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