WMOD00285 ‎(2)‎

• Title: Feasibility Study of Wintertime Cloud Seeding to Augment Arizona Water Supplies
• Date: 1/1/1987
• State: AZ
• Weather Modification - Doc Type: Report

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and representative precipitation mean, obtained by employing non-missing
station values (in a group) and only requiring that at least one station
be non-missing. Employing a number of stations in means generally leads
to precipitation estimates more representative of "truth" and with lower
variance (e.g., Klazura et al., 1985; Molanou, 1980).

After examination of the available records, a typical winter for each of
dry, normal and wet years was selected for illustration of results of
analyses. Specifically, the winter of 1982-83 was chosen as represen-
tative of a typical wet period, 1981-82 as a normal winter and 1980-81
as representative of a dry winter.

Precipitation amount categories were selected for analyses. These are
meaningful to weather modification in the sense that small events appear
to be modified by cloud seeding by greater percentage amounts than large
events (Medina and Super, 1985). Small events also generally occur with
higher frequencies. for most event analyses performed, cases included
in the various categories were those which accompanied non-missing
rawinsonde data collected at 1200 Z since the precipitation measurements
were taken at 1800 hours, local (one station at 1700). It is felt that
the 1200 Z sounding is most representative of the 24 hour precipitation
despite the temperature inversion problem. Precipitation amounts were
grouped as follows, employing English units for reader familiarity:

Precipitation categories (in)

o.
0.025
0.05
0.20
0.30
0.40
0.50
0.60
0.70
0.80

pcp = o.
< pcp ( 0.025
< pcp ( 0.05
< pcp ( 0.20
< pcp ( 0.30
< pcp ( 0.40
< pcp ( 0.50
< pcp ( 0.60
< pcp ( 0.70
< pcp ( 0.80
< pcp

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