WMOD00496

• Title: LOREP 1993 Summary Report: Airborne Measurements of Meteorological Variables, Atmospheric Particles and Sulfer Hexafluoride
• Date: 3/1/1996
• Weather Modification - Doc Type: Report

Denver. A remote weather station was located near the Jackson Creek site which provided a record
of wind, temperature and humidity during seeding operations. Three mountain-top icing stations
were established to provide critical information for seeding decision making. Each station had
temperature, relative humidity, wind speed, wind direction, and icing sensors. Data were collected
at 5-minute intervals and transmitted once per hour through GOES satellite. To complete
measurements a rawinsonde system collected data including pressure, temperature, relative humidity,
wind speed and direction from the surface to 10 Ian.
A Cooperative Agreement between the U. S. Bureau of Reclamation and the National
Oceanic and Atmospheric Administration provided the NOAA King Air research aircraft, equipped
for cloud microphysical investigation, for the two-month field program. The instrumented aircraft,
with a flight crew of two pilots plus a scientific observer, was deployed along Grizzly Ridge at
altitudes between 2590 m and 4115 m (8,500 and 13,500 feet mean sea level (MSL)). Wind
direction was from the south or southwest for all flights.
The aircraft made ten research flights as part of the program. The first flight was for test
purposes and to familiarize the pilots with the area while in Visual Flight Rules (VFR) conditions.
We observed tracer gas concentrations on these flights that ranged between 5 and 330 pptv.

2. OBJECTIVES

The State of California Department of Water Resources lists the scientific objectives of
program in order of importance as:

I. Evaluate the accuracy of targeting seeding effects using a combination of
rawindsonde data, mountaintop wind, temperature, and icing information,
tracer releases, and ground and aircraft microphysics observations.

2. Document the changes in crystal concentration, habit, degree of rime, and
change in integrated water during experimental seeding using ground and
aircraft microphysics data.

3. Compile precipitation data for the target and covariate gauge sites for
randomized seed, no-seed days. These data will be used in statistical evaluation
of seeding effects.

3. DATA COLLECTION

3.1 Methods of collection

The airborne data collection platform was a Beechcraft King Air Model C-90, twin-engine
turbo-prop, described in further detail by Wellman et al. (1989). The research aircraft was fully
suited for operation under instrument flight rules and was equipped for flight into known icing
conditions. The aircraft operations and aircraft were based in Reno, NY, at the Reno-Cannon
International Airport, not far from the target area. Ground based operations, other than aircraft, data
collection sites, and results are thoroughly described in the Lake Oroville Runoff Enhancement

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