WMOD00296 ‎(2)‎

• Contract/Permit #: 14-06-D-5640
• Title: Park Range Atmospheric Water Resources Program Final Report
• Date: 9/30/1969
• Weather Modification - Doc Type: Report

The second pertinent snow sampling problem is that contamination is a real
problem. The collection equipment and materials, personnel vehicles, and
analysis facility and personnel must be completely physically separated
from any personnel, equipment, or vehicles that are ever used in any phase
of the nuclei or tracer generation process. The results of the first season's
neutron activation silver analyses were made suspect by contamination,
even though what was thought to be adequate safeguards against contamina-
tion had been enforced. The sometimes puzzling results of the sample anal-
yses of other programs can possibly also be attributed to contamination of
the .samples at some stage of the procedure. The total material we are look-
ing for in several seasons of sampling and tracer experiments is probably
less than the dust under one's findernail, so contamination is a very real
problem to be rigidly guarded against. Also, care must be taken to guard
against pollution or dilution of a sample by blowing or drifting snow.

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2. 9 Snow Sensor Network

The snow sensor network as of the conclusion of the project consisted of
eighteen sensor locations as located in Figure 12. The instrumentation con-
sisted of an 9.ptical sno~ rate sensor which int~grate's-the pu~~pr?~~~d
by_snow-cry~~al~_.fallin!L!hrough ~a ~~ght bea.~_-phptC?.s:.(;ll_~!!. At al1'but
Three sites moaified weighing bucket gauges were also used. These con-
sisted of standard weighing gauges with the collection area doubled over
the standard eight inch diameter gauge.

The weighing bucket sensor with a standard alter type wind shield definitely
tends to underestimate the actual snowfall. Figure 13 is a comparison of
the seasonal record of accumulative snowfall as indicated by the weighing
bucket snow sensor and the measured special snow course values. After
five seasons experience with the complete series of special snow course
measurements there is no reason to believe the snow course values are over-
estimates of precipitation. In fact, they are the most accurate measures of
accumulated snowfall available; but the time resolution of the measurements
does not make them suitable for the determination of a short period snowfall
total.

JJ

The USDA Soil Conservation Service (SCS) operated a network of five tele-
metered snow pillows and EG&G operated a sixth in support of the project.
Also, a network of 25 snow qourses were read approximately weekly by the
SCS in support of the project. The network was rounded out by the two
existing stream gauges with long periods of record, and eight additional
gauges installed and operated by the U. S. Geological Survey and the USDA
Rocky Mountain Range and Forest Experiment Station.

During routine operations the network was serviced on approximately a
weekly schedule. The optical rate sensors operate more reliably if the
batteries are not operated past seven days. Section 2. 9. 1 describes the

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