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

-?
/I' '7
~'feV~ '

OI"t'1
"::;;e.~ 1

~

quently analyzed for silver content by an atomic absorption spectrophotometer.

1. 3.4

Replica Analysis and Identification of Silver Iodide Ice Nuclei

$

Several thousand snow crystal replicas were collected on plastic-coated glass
~ slides ana' an-alyzed for'"c.rystal habltini:elation-to'seeding. Originally, an
elec microscope technique was employed for identifying silver iodide par-
ides which were located at the center of snow crystals, and had thus served
as ice nuclei. However, this technique was expensive and during the 1968-69
season a new less expensive technique was developed and used with significant
results.

1. 3.5

Radar and Radiosonde Measurements

Throughout the project a radar balloon tracking facility was operated at Mt.
Harris (20 nmi west of the target) for obtaining upper wind measurements at
1 to 3 hour intervals. A 403 MHZ radiosonde system was used initially, and
after January 1967, 1680 MHZ radiosonde information was available from
Mt. Harris at 3 to 6 hour intervals. PPI photographs from Mt. Harris were
also valuable analysis aids, as was AGe vertical-pointing data from a GPG-1
radar, located between the AgI release site and the target area. The measure-
ments from the radiosondes and tracked balloons were used extensively in all
analyses. In fact, it was found to be absolutely mandatory to have frequent
measuremerits of this type for satisfactory analysis under the two main experi-
mental designs employed in the Park Range Project.

......,

1. 3. 6

Diffusion Tests

~

In order to adequately analyze for seeding effect, a reliable description of
the diffusive characteristics of the released seeding material is required.
This was difficult as no adequate model of diffusion was known to exist for
mountainous topography. Thus, a large number of diffusion tests were made
using both ground and airborne releases of phosphorescent partiCles and
silver iodide tracers. Lithium stearate was used as an inert tracer in sev-
eral dual tracer tests. Plume tracking downwind was made by aircraft, and
also at the surface in the target area.

1. 4 Analysis Procedures

The analysis procedures for 1968-69 were considerably different than for
previous years, due to the major change in experimental operations design,
and also due to the availability of a numerical model of orographic flow and
precipitation. In years prior to the 1968-69 season, the analysis emphasis
was on power spectral procedures using pulsed seeding data, along with
analyses of snow crystal type, ice nuclei count, and snow samples collected
for obtaining silver concentration. The analysis procedures for 1968-69

...,

.

4