WMOD00405

• Title: Thermodynamic Features Affecting Convective Cloud Growth and Dynamic Seeding: A Comparitive Summary of HIPLEX Soundings 1975-1977
• Date: 7/1/1981
• Weather Modification - Doc Type: Report

related to convective cloud development on the High Plains. Previous

studies by Hirsch (1971) showed that the GPCM-diagnosed cloud tops and
radar echo tops had a correlation coefficient of 0.82 (sample of 40 cases).
Similar studies by Simpson and Wiggert (1971) showed that their model

also had reasonably good correlations. Appendix 1.1 provides more

detailed information regarding model vs. aircraft verification analyses.

e. Predicted Convective Intensity vs. Observed Cloud Types

Model analyses of conditions on days having satellite observations of

clear, cumulus, cumulus congestus, and cumulonimbus at the three primary

HIPLEX sites (MLS, GLD, BGS) were compared. These subjective visual
cl assifi cations of satell ite photos showed that many of the model..

diagnosed lapse rates, moisture, and cloud properties varied in a manner

consistent with the increasing intensity of the four cloud types. These
variations agreed with theoretical expectations. Table 4 presents a set
of these cases where convective cloud sample statistics of cloud-top areas
were derived from digital satellite observations (Reynolds et a.l., 1978)
from 1976 and 1977 HIPLEX field seasons. The digital imagery were analyzed
using a man-computer interactive video display system (ADVISAR)1J which

permitted the manual selection of appropriate clouds and elimination of

contamination problems of cirrus and nonconvective clouds. These cases

were selected and analyzed independently from the subjective photographic
interpretation of the four cloud types. In this sample of 49 days,
multiple regression analyses were performed to determine linear relation-
ships between model-analyzed thermodynamic variables and cloud properties,

1/ All Digital Video Imaging System for Atmospheric Research at Colorado
State University.

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