WMOD00313

• Title: Cloud Physics Studies in Utah During 1978
• Date: 9/1/1978
• State: UT
• Weather Modification - Doc Type: Report

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CHAPTER 2
DESCRIPTION OF INSTRUMENTED KING AIR AIRCRAFT

The Wyoming KIA has been described in detail by Cooper (1978). A
summary of its instrumentation is presented in Tables 2.1.1 and 2.1.2, and
an example of the images obtained by the 2D-probes is shown in Figure 2.1.1.
In addition to the instruments described by Cooper, we also had onboard an
NCAR ice nucleus counter. Data have been presented by Marwitz ~~. 1978
showing that when the aircraft was flown through a sharp, distinct plume
of Agl, the NCAR counter would indicate the maximum concentration of ice
nuclei ~ 65 s later. Approximately 35 s after the observed peak in con-
centration, the NCAR counter would then indicate concentrations having a
value of 37% (e-1) of the peak concentration.
We experienced four equipment problems with the KIA during the field
project. During the first two flights on 12 March it was noted that the
indicated airspeed system malfunctioned during rapid descent. The aircraft
was flown back to Laramie and a permanent fix was made. No subsequent
problems were experienced with the indicated airspeed system.
During the project, the MRI turbulence system was determined to be
reading too high. The system was subsequently returned to the manufacturer
for repairs, and it was not available for the rest of the season.
The static pressure transducer produced a large number of spike-type
signals. These spikes permeated into a large number of other derived
parameters which are dependent on static pressure. The spikes are readily
evident in the analog traces.
Accurately measuring the liquid water content was the most difficult
problem. A Forward Scattering Spectrometer Probe (FSSP) and a Johnson-
Williams (JW) liquid water content Instrument were operated on the KIA.
We determined the liquid water content by integrating the FSSP spectra.
However, data obtained from these two sources consistently showed poor
agreement in that the liquid water contents obtained from the FSSP were
almost always higher than the liquid water contents measured by the JW
instrument. An example of the correlation between these instruments is
shown in Figure 2.1.2. This figure is a scatter diagram of FSSP water

3.