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<br />1876 <br /> <br />JOURNAL OF CLIMATE AND APPLIED METEOROLOGY <br /> <br />VOLUME 22 <br /> <br /> <br />Carmichael <br />McCLELLAN A/. <br />FORCE BASE .. . <br /> <br />~!I..;._.-: ..-~r.U:-N <br />/' t.~. -... <br /> <br />'" ~f <br />~ ,,'I) <br />: (.0 <br />t '" <br />.. 0 <br />.. <br />.. <br />Q <br />CIl <br /> <br />SIERRA COOPERATIVE <br />PILOT PROJECT <br /> <br />o 101'20 <br /> <br />/ <br /> <br />SCALEOFMllES <br /> <br />, 0 , 10 IS 20 >0 <br />- - - I <br />SCALE OF KilOMETERS, <br /> <br />FIG. i. The Sierra Cooperative Pilot Project study area (outlined). <br /> <br />a. Airborne data acquisition techniques <br /> <br />The University of Wyoming operated a Beechcraft <br />Super King Air 200 aircraft during the winters of 1978- <br />79 and 1979-80. Two measurement systems were used <br />to determine the L we. A forward scattering spec- <br />trometer probe (FSSP), described by Knollenberg <br />(1976), provided a continuous measurement of the <br />cloud droplet spectrum from which the L WC was cal- <br />culated. The FSSP measured droplet diameter from 2 <br />to 30 JLm in 2 JLm intervals. A Johnson-Williams (JW) <br />hot wire device provided an independent means of <br />determining L we. The measurement aspects of these <br />two instruments were studied by Marwitz and Stewart <br />(1981). In regions where the JW -derived L WC was less <br />than 0.1 g m-3 the FSSP LWC was used, otherwise <br />the JW was the primary device. The JW was shown <br />by Knollenberg (1972) to be restricted in regions of <br />low L We. In addition, Strapp and Schemenauer (1982) <br />also discussed measurement dependency of several JW <br />devices with airspeed, temperature, and the amount <br />of LWe.Ice crystal measurements were made with a <br />2D-C optical array probe which is described by Knol- <br />lenberg (1976). The 2D-C recorded particle diameter, <br />shape, and concentration in the range of 25 to 800 <br /> <br />JLm at 25 JLm intervals. Processing software and other <br />aspects of the King Air instrumentation have been <br />described in detail by Cooper (1978). <br /> <br />b. Skywater radar <br /> <br />,A 5.4 cm wavelength SKYW A TER radar was lo- <br />cated near Sheridan, California. The radar range was <br />140 km. Programmed volume scans were made at 5 <br />min intervals. The radar was capable of detecting min- <br />imum equivalent reflectivities of 6.5 dB(Z) at 50 km <br />and 14.5 dB(Z) at 125 km. Additional technical in- <br />formation regarding the SKYW A TER radar can be <br />found in Schroeder and Klazura (1978). <br /> <br />3. Stratification of data <br /> <br />Digital radar data, collected in support of aircraft <br />operations, were stratified by seven precipitation echo <br />types (PET) as described in Table I and shown in Fig. <br />2. A PET was classified from plan position indicator <br />(PPI) scans. <br />Analysis ofSCPP rawinsonde data, which were taken <br />near Sheridan, California, has shown that the echo <br />