WMOD00472

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

There are 12 different possible cloud types for detennination by the SFM, including "clear" and
"unknown" as two of the classifications. The other 10 types are stratus, stratocumulus,
cumulus, nimbostratus, altocumulus, altostratus, cirrostratus, cirrus, cirrocumulus, and
cumulonimbUs. Cloud type is selected for a particular layer according to the lapse rate of
equivalent potential temperature and layer average temperature. No adjustments were made
to this process in the adaptation for Arizona.

Modeling results

Adaptation of the SFM included alteration of the input routines to iteratively handle 80undings
that had been interpolated for processing by the LSPM (Local-Scale Orographic PrElcipitation
Model). Once the model was operable, parameter settings were detennined by fitting the 1987
CLW measurements through trial model runs with CVR soundings. The CLW values employed
were the usual 7-h means used in the previous regressions. The CVR soundings used were
those that properly matched the CLW values.

Given in table 2(a) are MLR results obtained with SFM estimates as one of the independent
variables. Prior to MLR application, the model was individually applied to CVR, INW, and TUS
soundings. With SFM estimates on CVR soundings and INW 750-mb wind speed as
independent variables, a multiple correlation of 0.72 was obtained. As a single independent
variable, the model estimates from CVR soundings yielded a correlation value of 0.59. The 0.59
value was also obtained with the independent variables SFM estimates on TUS soundings and
INW 750-mb wind speed, as indicated in table 2(b). The multiple correlation was slightly lower
with the variables, model estimates from INW soundings, and INW 750-mb wind speed. The
correlation was 0.49 with only the model estimates from TUS as the independent variable.

Table 2. - Multiple regression results with SFM estimates as an independent
variable and HJ CLW as the dependent variable1.

Independent
variables

Multiple
correlation

Root mean
Adjusted R2 squared error

(a)

XI: S-F model results on CVR soundings
X2: INW 750-mb wind speed

0.72 0.52 0.040
Regression equation: Y' = -0.0211+0.1419X1+0.OO44X2

(b)

XI: S-F model results on TUS soundings
X2: INW 750-mb wind speed

0.59 0.35 0.045
Regression equation: Y' = -0.0098+0.149OX1+O.0037X2

lDependent variable - the HJ CLW estimate is defined in table 1.

SUMMARY AND DISCUSSION

The primary purpose of task 1 of this study was to determine a method or mE!thods for
estimation of CL W content in winter clouds on the Mogollon Rim. The technique had to be
applicable to historical sounding data for estimation of CL W during that period. The rationale

15