WMOD00472

• Title: Estimation of Cloud Liquid Water in Winter Storms on the Mogollon Rim
• Date: 5/1/1993
• Weather Modification - Doc Type: Report

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Figure 1. - Mogollon Rim of Arizona with locations of ground instruments employed In the 1987
experiments (Super et aI., 1989).

periods would assume robustness of the equation. Useful applicability requires that the
operative processes be stationary and that historical information used in developing the MLR
equation cover a broad spectrum of, in this study, cloud behavior. If these conditions are
generally satisfied and substantial variance (generally more than 50 percent) is explained by
the regession, extrapolation in time can produce useful estimates. Because one seldom knows
the extent to which regression prerequisites are satisfied, the applicability of a regression equa-
tion is not completely known. However, lengthy historical data sets and a thorough knowledge
of the operative physical processes improve estimation of the applicability of regressions.

The link from the 1987 experiments to a lengthy historical study period was the availability of
twice-daily soundings for the 10 winters of 1978-1988 for DRA (Desert Rock), INW (Winslow),
and TUS (Tucson). Those soundings had been employed in precipitation modeling for the
Mogollon Rim. They were used here as a source for independent variables in the appli<:ation of
the MLR procedure.

Initial data analysis focused on the comparison between sounding locations of like sounding
variables (time matched by no more than one hour's difference) of temperature, relative
humidity, wind direction, and wind speed, each at 50-mb levels up to 500 mb. A demonstrable
relationship should exist between like variables of concern for say, TUS and CYR, if TUS is to
act as a substitute for CYR information. Such relationships were of particular interest in the
case of CYR versus INW variables because a lengthy record existed for INW and its near
proximity to the rim at about 120 km, suggested it might well serve as a surrogate fc)r CYR.
Soundings from CVR were considered to best represent conditions over the rim. Either singly or

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