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<br /> <br />. <br /> <br />2. OBSERVATIONAL FACILITIES AND NUMERlCAL MODEL <br /> <br />2.1 Xnstrumentation <br /> <br />2.1.1 Arizona <br /> <br />f" <br />I <br />I <br /> <br />The data that will be discussed for the Arizona cases were collected as part of <br />the Arizona Snowpack Augmentation Program (Super et al., 1989), conducted during <br />part of the winters (January to March) of 1987 and 1988. During the winter of 1987 <br />measurements were concentrated at Happy Jack, south of Flagsta.:fF, on the crest of the <br />Mogollon Rim (Figure 1), while observational facilities were moved to Hannagan Meadow <br />in the White mountains near the border with New-Mexico during the winter of 1988. <br />Only measurements collected during the 1987 season will be considered in this thesis. The <br />principal observational systems used during this perio~ were a C-b&J1d weather radar, a <br />mierowave radiometer, &J1 acoustic sounder, &J1 ice particle imaging probe, a high resolution <br />precipitation gauge and an automatic weather station all located at Happy Jack R&J1ger <br />station. To obtain wind profiles in the lower atmosphere pibal balloons were launched from <br />Happy Jack whenever conditions were favorable. <br /> <br />. <br /> <br />i <br />I <br />I <br />,. <br /> <br />, . <br />i <br /> <br />i <br />I <br />L .. <br /> <br />The Surveillance Weather Radar (SWR-86) C-band (5.4-cm. wavelength) radar was <br />operated in RBI (Range Height Indicator) mode to monitor the vertical reftectivity <br />structure of clouds &J1d precipitation during all storm events. It also provided estimates of <br />cloud base &J1d cloud top heights. A RBI IC&J1 was conducted every five minutes during all <br />storm episodes. No data were collected between storm periods. The mierowave radiometer <br />was operated in a vertically pointing mode measuring the integrated amounts of water <br />vapor &J1d liquid water along a vertical colUDUL of air determined by the instrument's <br />field of view (2.5 deg). It operated in a passive mode monitoring incoming radiation at <br />two wavelengths of 1.45 em (20.6 Ghz) &J1d 0.95 em (31.6 Ghz). The acoustic Doppler <br />sounder (AeroVuonment Model 2000) was used to provide vertical profiles of wind speed <br /> <br />, .. <br /> <br /> <br /> <br />. <br /> <br />23 <br />