Impact of inferred latent heating rates on predictions of convective storms
Date
1991-11-08
Authors
Henry, Sandra L. Grant, author
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Abstract
A localized ordinary thunderstorm system occurred during the Convective Initiation and Downburst Experiment (CINDE) , in the Denver, Colorado area on 29-30 July 1987. The three-dimensional, nonhydrostatic version of the Regional Atmospheric Modeling System (RAMS) , developed at Colorado State University, was utilized in this case to investigate the impact of forced latent heating rates on short-range (12 hours or less) quantitative precipitation forecasts (QPFs). This was accomplished by using estimated convective precipitation rates , in a modified Kuo-type convective parameterization scheme, to determine the vertical-distribution of latent-heating rates. The inferred heating rates were then used, instead of the model predicted heating rates, to guide the model to a more desirable state. The sensitivity of the model to a variety of precipitation rates and the impact of the duration of simulation time are also examined. The 12 hour simulation with no forced heating failed to predict any precipitation in the northeast Colorado region. On the other hand, while the 24 hour simulation with no forced heating did predict precipitation in the northeast area of interest, the precipitation was positioned too far north of the observed precipitation area and the intensity was too small. In general, 12 hour simulations that used forced heating rates, for a one hour period during the simulation, produced the most improved precipitation forecasts. However, the results were extremely sensitive to the various precipitation rates used to obtain the forced heating rates, with weaker values having no impact at all and the strongest rates producing the most improved forecast.
Description
November 8, 1991.
Also issued as author's thesis (M.S.) -- Colorado State University, 1991.
Also issued as author's thesis (M.S.) -- Colorado State University, 1991.
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Subject
Convective clouds
Rainstorms