WMOD00297 ‎(2)‎

• Project Name: Project Skywater
• Title: Project Skywater - Fiscal Years 1975-78 Report
• Prepared By: US Department of Interior Bureau of Reclaimation
• Date: 3/1/1979
• Weather Modification - Doc Type: Report

(8) Changes in raindrop size distributions within a given storm
result in significant changes in the R vs. Z relationships.

(9) Changes in the average R vs. Z relationships between storms
are greater than changes within a given storm.

(10) Of the various R vs. Z relationships used with the radar
measurements, the greatest improvement in radar surface rainfall
estimates resulted from relationships derived from the PMS
measurements.

(11) Relationships derived from correlations between measurements
of the low-response surface gages and the high-response radar
result in radar estimates of surface rainfall which are relatively
inaccurate.

(12) The gage/radar relationships derived from measurements in
gage clusters result in radar surface rainfall estimates which are
slightly improved over those derived from an identical number of
gage measurements spaced evenly throughout the network. Although
confidence cannot be given, statistical considerations indicate
that the area representiveness of the individual gage measurements
is minimized in the gage cluster arrangements and, therefore,
results in relationships which are likely to be more accurate.

(13) Although this study did not investigate the possibility of
further improving the surface rainfall estimates from those
obtained from the various R vs. Z relationships, the results
indicate that the reliability of radar rainfall estimates will not
necessarily be improved by adjusting the radar estimates by a
single GT/RT ratio value. This is due to the high probability
that the exponent of the gage vs. radar comparison equation
differs significantly from the value of 1.

(14) No significant degradation in radar estimates of surface
rainfall over a large area results with the less frequent acquisi-
tion rate of 0.2 rim.

CONTRACTORS: Kansas-Colorado-Nebraska
CONTRACT NO. 14-06-0-7544 (Memorandum of Understanding)
PRINCIPAL INVESTIGATOR: Not appplicable
PERIOD: July 1,1974, to September 30,1978
FUNDING: None

The States of Kansas, Colorado, and Nebraska, and the Bureau of
Reclamation signed a Memorandum of Understanding to acquire and

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