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Table 2.2. - Propane dispenser site locations. Station 3- Letter ID Latitude (X) Longitude (W) Elevation Cml Site d1 ~IET 39.77 120.84 2122 Site d2 PLC 39.63 120.73 2097 Site d3 PCT 39.69 120.79 2171 Site d4 GIB 39.71 120.78 2239 Site d5 ATR 39.72 120.77 2140 Site d6 SPL 39.70 120.73 2182 Site d 7 WDL 39./1 120.72 2225 Site d8 ROL 39.68 120.68 2280 Site d9 BRC 39.64 120.68 2207 Site d10 DRL 39.65 120.66 2220 A typical dispenser site set-up is shown on figure 2.4. The filled propane tanks and dispenser were mounted on a metal pallet and were helicoptered to each site as a single unit. The dispenser has both radio receiving and transmitting capability. This feature provided on-off control of the propane release from the Sacramento POC (Project Operations Center) and confirmation of release by monitoring both nozzle temperature and flow rate. A coded transmission was used via a microwave repeater atop Beckwourth Peak .osee fig. 2.1) to initiate or terminate seeding. The exact details of the transmission sequence and radio system were determined by DWR's Office of Communications. Each station had a separate identification and thus could be interrogated separately. Details on the propane dispensers are given in appendix C. Minor problems were noted with sites d7 and dl0 during the 1992-93 winter season. Site d7 experienced communication problems and site dl0 had a microcomputer failure the last 18 hours of seeding. A magnetic latching valve was installed on all dispensers. It required a momentary 12 V to actuate and a second 12 V to deactivate. These momentary po\\-er requirements significantly reduced power drain on the dispenser battery, which allowed many more hours of seeding during extended cloudy weather before the battery charge fell below 12Y Mter December 30, 1992, with the continued heavy snowfall, several dispensers were buried, which cut off all light to the solar panels (sites d4 and d9J. In addition, several valve boxes were torn off towers because of extreme icing and winds (sites d6 and d8). Before the 1993-94 winter season, all valve boxes were reinforced and a third solar panel was installed looking down at the anti-sun direction so that the panel would not be impacted by falling snow or rime ice. The 1993-94 winter season was excessively dry; consequently, heavy snowfall or rime icing caused no problems. 2.3 Rawinsonde Observations Rawinsonde systems were used to collect upper-air atmospheric data from the surface to the 300-mb level (if p05sible) or about 10 km m.s.!. The data collected included pressure, temperature, relative humidity, wind speed, and wind direction. 8