WMOD00426

• Title: Desert Research Institute Fields Operations - 1994 NOAA/UTAH Field Program - Final Report
• Date: 11/1/1994
• Weather Modification - Doc Type: Report

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I. Introduction

The continuing research under the cooperative Atmospheric Modification Research
Program (AMP) between the National Oceanic and Atmospheric Administration (NOAA)
and the state of Utah included a winter field program from 15 January through 15 March
1994. The emphasis of this program on the Wasatch Plateau in central Utah was the
documentation of the transport and dispersion of silver iodide (Agl) cloud seeding
aerosols from ground-based generators. The Utah Department of Water Resources
(UDWR, 1994) described the,plan for the field program which included participation by
numerous other agencies, including the Desert Research Institute (DRI).
The DRI participated in a number of the 1994 field activities including mobile
microwave radiometer operations, Ka-Band radar operations, rawinsonde operations, the
collection of time sequential snow samples for analysis of silver, the archiving of pertinent
satellite and synoptic weather data, and the deployment of two remotely-controlled
generators for dispensing Agl. These activities were aimed at describing the spatial
distribution of supercooled cloud liquid as in Huggins (1994), describing the spatial
distribution of cloud ice from scanning radar data, and verifying the presence of cloud
seeding material in snowfall at the project's primary target site. Radar data are also
expected to contribute to transport and dispersion studies through the analysis of radar
returns resulting from chaff being released from seeding generator sites. The upper air
soundings were used to provide initiation input for the mesoscale modeling aspect of the
program (Heimbach, 1993), as well as data for deriving atmospheric retrieval coefficients
for microwave radiometric data and important information on the stability of the
atmosphere during the release of seeding material. The 1994 NOAA/Utah project area
and primary instrumentation sites are shown in Fig. 1.
Overall the DRI work contributed to the scientific objectives of the NOAA/Utah
Project, which are: 1) to describe the spatial and temporal distributions of supercooled
liquid water (SLW) in winter clouds over Utah's mountains and the factors controlling
the SLW; 2) to understand how silver iodide cloud seeding material may be delivered
from ground generators to the winter cloud regions containing SLW; 3) to gain a better