WMOD00308

• Title: 1991 Final Report of Desert Research Institute Field Operations, Data Collections and Data Processing
• Prepared For: Utah Department of Natural Resources Division of Water Resources
• Prepared By: Arlen W. Huggins
• Date: 8/1/1991
• State: UT
• Weather Modification - Doc Type: Report

radiating temperature of the atmosphere at 20 and 30 GHz are determined from a

set of radiosondes that encompass the period of radiometer data. The entire set

of 1991 Mt. Pleasant soundings will be used for these calculations. Real time

measurements during the 1991 season were made using a set of retrieval

coefficients derived from a set of 1987 soundings taken from Beaver, Utah. Data

for 1991 will be archived only after the new coefficients are applied to the raw
data.

For mobile radiometer data, it will likely be necessary to apply an

........-~-"-~-.~.....---

adaptive retrieval relationship to the data. This is due to the fact that

altitude changes were typical along the radiometer routes and the retrieval

relationships can be expected to change with altitude. In fact, the baseline

values of liquid and vapor were observed to drift with the changes in altitude

when a constant set of coefficients was used. Figure 9 demonstrates this effect

during a traverse of Route 1 on 28 February 1991. No liquid existed in the

clouds over the Plateau from 0830 to 0915 as the radiometer descended from the

DOT site to the valley, yet the liquid depth baseline increased from about .05
mm at the top of the Plateau to .15 mm at the bottom of the Plateau. Vapor depth
also increased, but much of the change in vapor can be attributed to an increase
in microwave emission from additional moisture in the lowest layer of the
atmosphere. Retrieval coefficients from the 1991 soundings will be processed

using the surface and numerous levels above the surface as the base level. From

this multiple set of coefficients an altitude-dependent relationship will be
determined and applied to the raw data.

D. Ka-band Radar Maintenance
The Utah Ka-band radar was maintained during the 1991 Field Program by DRI

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