WMOD00455

• Contract/Permit #: 14-06-D-6842
• Title: Research and Development Technique for Estimating Airflow and Diffussion Parameters Related to the Atmospheric Water Resources Program
• Date: 9/1/1969
• Country: United States
• Weather Modification - Doc Type: Report

5) Establish modeling criteria for future operational programs
in weather modification.
The laboratory or wind tunnel method consists of obtaining concen-
tration measurements of a dispersing tracer material over a scale model
of selected terrain placed in a simulated atmospheric flow. Standard
field measurements of temperature, wind direction and velocity and
measurements of tracer concentrations by ground stations and aircraft
for selected meteorological conditions are used to confirm and/or
evaluate the physical model's results.
The laboratory program involves three selected topographic regions
where operational cloud seeding is in progress. These areas are:
1) Eagle River Valley-Climax area of Central Colorado,
2) Elk Mountain area of southern Wyoming, and
3) The San Juan Mountain area of southern Colorado.
The field program is limited to the Climax-Eagle River Valley area;
the availability of field data for the other areas were dependent on
private contractors and the University of Wyoming's Natural Resources
Research Institute.

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Procedures for Completing Objectives
In order to fulfill the stated objectives the following procedures
were completed. First, the various parameters influencing the transport
and spread of a particulate plume downstream from a source are cate-
gorized under four principal headings: 1) source characteristics, 2)
depletion mechanisms, 3) atmospheric motions, and 4) boundary conditions.
The existing laboratory airflow types are reviewed along with their
restrictions.
The general mathematical aspects of two laboratory airflow models
and the relevant similarity parameters governing their airflow charac-
teristics were developed from existing similarity theory and information
on past studies of modeling.
Second, to satisfy the basic requirement of geometric similarity
scaled topographic models of the three topographic areas were constructed
and arranged in wind-tunnels for the necessary experimental work.
Third, several laboratory experiments were conducted on the simula-
tion of the atmospheric planetary boundary layer and transport-dispersion
of a passive (radioactive) tracer over the scaled topographic models.
Two model airflow types were explored, a neutral and barostromatic.
Three different wind tunnels were utilized for the various experiments.
Fourth, field observations of temperature, wind velocity with
height, surface concentrations, dispersion and transport estimates from
constant-volume balloons and aircraft sampling of silver-iodide were
obtained, analyzed and interpreted to provide information on the weather
conditions and how these conditions affected the dispersion of the seeding
material.
Fifth, the laboratory simulation results for each topographic area
were compared with the available field data for geometric, kinematic,
thermal and dynamic similarity. For the most part, this was accomplished
by utilizing the relevant similitude criteria. The model's dispersion
results were also compared with the available field data to evaluate
how well the models approximate actual field conditions. In addition,
the model and field results were used to assess the value of the labora-
tory experiments. for assisting weather modification field programs in
cloud seeding.

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