Estimating Rainfall in Regions of Active Convection

Arnold Gruber National Environmental Satellite Service, NOAA, Washington, D.C. 20233

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Abstract

An attempt to estimate rainfall in convectively active regions using Kuo's parameterization scheme has been made. The precipitation in this model is given by P = lQ1t, where P is the precipitation per unit time, l the fraction of a synoptic area covered by deep active convection, Q1 the mount of condensation heating according to moist adiabatic ascent, and Δt a time parameter related to the precipitating lifetime of the convective elements.

Investigation of the above equation when P, l and Q1 were available indicated that an appropriate time parameter was 30 min and that the main contribution to the precipitation comes from the l parameter.

A case is presented where l is obtained from satellite observations. The resulting precipitation estimate appears quite reasonable. The potential for estimating precipitation over the tropical means is pointed out.

Abstract

An attempt to estimate rainfall in convectively active regions using Kuo's parameterization scheme has been made. The precipitation in this model is given by P = lQ1t, where P is the precipitation per unit time, l the fraction of a synoptic area covered by deep active convection, Q1 the mount of condensation heating according to moist adiabatic ascent, and Δt a time parameter related to the precipitating lifetime of the convective elements.

Investigation of the above equation when P, l and Q1 were available indicated that an appropriate time parameter was 30 min and that the main contribution to the precipitation comes from the l parameter.

A case is presented where l is obtained from satellite observations. The resulting precipitation estimate appears quite reasonable. The potential for estimating precipitation over the tropical means is pointed out.

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