WMOD00281

• Title: Application of a Simple Local-Scale Numerical Model in the Study of Altered Climate Impacts on Watershed Precipitation
• Prepared By: J. G. Medina
• Date: 1/1/1989
• State: AZ
• Weather Modification - Doc Type: Report

The model utilizes thresholds for a number of
other parameters such as average relative humidity for
key layers that indicate whether a sounding is "dry" or
"wet" and thus whether a full computation should be
performed. Some analysis on the sensitivity of these
parameters has been performed to improve model
capability, but additional work is needed.

4. ~ESULTS AND DISCUSSION

Sounding data from MM4 runs were available
for January 1979. Consequently, results included
herein of model applications are for this time period
only, for both geographical areas studied. Matthews
et al. (these proceedings) discusses meteorological
features of the MM4-produced soundings.

Precipitation data to be used for model
verification and improvement were obtained for
24 gauges in or near the Delaware River watershed
and 11 gauges on the Mogollon Rim. Daily mean
values were developed for each of the two groups of
gauges. The model was configured to estimate daily
mean values for two groups of points (in the model
domains) that correspond to the gauge locations.

Figures 4 through 6 respectively show
contoured results (51 by 48 grid points for the
Delaware and 45 by 35 grid points for Arizona) of
model-estimated monthly sums for January 1979 for
the Mogollon Rim with DRA, INW, and TUS
sounding data as input to the model; Mogollon Rim
with MM4-generated sounding data as input; and the
Delaware River watershed with PIT sounding data.

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II
d
4?
66
"
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U
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:16
II
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Zll
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11
.
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II

Fig. 4, Model-produced Arizona precipitation for
January 1979 with DRA, INW, and TUS soundings as
model input (contours in inches).

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II II

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U
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u

Fig. 5. Model-produced Arizona precipitation for
29 days of January 1979 with MM4-produced
soundings as model input (contours in inches).

11 13 15 17 1921 2J 25 'Zl 29 31

...3
...1
J9
J7
J6
33
31
29
27
25
2J
21
19 '9
17 17
15 15
13 13
11 11
9 9
7 7
5 5
3 3
1
1 3 5 7 9 11 13 15 17 19 21 2J 25 27 29 31 33 :E

Fig. 6. Model-produced Delaware River watershed
precipitation for January 1979 with PIT soundings as
model input (contours in inches).

The orographic nature of the model-produced
precipitation on the Mogollon Rim (Figs. 4 and 5) is
clearly evident with the highest terrain obtaining the
greater amounts of precipitation. Comparing results in
Figures 4 and 5 suggests the main effect of MM4-
produced soundings is a general increase in the
precipitation amount.