WMOD00590

• Title: Analysis and Classification of Mesoscale Cloud and Precipitation Systems
• Date: 8/1/1983
• Weather Modification - Doc Type: Report

of storm and near-storm conditions in two-dimensional models of

Orville and Kopp (1977), Murray (1970), Hane (1973), Ogura and Chen
(1977) and Soong and Ogura (1980). Three-dimensional models have
furthered our understanding of the roles of shear, low-level conver-
gence, and mesoscale vortices (e.g., Betts et al., 1976; Miller and
Pearce, 1974; Wilhelmson, 1974; Schlesinger, 1975; Moncrieff and
Miller, 1976; Kreitzberg and Perkey, 1977; Klemp and Wihelmson, 1978;
Cotton and Tripoli, 1978; Anthes and Warner, 1978; Clark, 1979;
Brown, 1979; Fritsch and Chappell, 1980a). _ Recent simulations of
mature supercell storms in three-dimensional time-dependent models
show that mesoscale vortices associated with tornadic activity and
strong vertical shear can be predicted in reasonably good agreement
with Doppler radar observations. Klemp and Rotunno (1982) simulated
the fine scale structure of low-level storm-scale vorticity fields
and interactions of the downdraft outflow with updrafts along a gust
front. Simulations by Tripoli and Cotton (1980) and Simpson et ale
(1982) of much less vigorous tropical cumulus and cumulonimbus clouds
further show the important role of low-level convergence, lifting and
vertical wind shear in controlling the intensity, duration and amount
of convective development and precipitation.

Numerical modeling efforts which simulate cloud-environment
interaction on the meso-y to meso-a scales span the range of grid
domains from 2 to 2500 km and have grid spacings from 0.2 to 100 km
with time steps from 1 s to 0.1 h. The large range of scales pro-
vides good background from which one must select the most appropriate
scale for study in mesoscale triggering of convective cloud develop-
ment. Modeling results show that on scales of 20 to 40 km, much
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