WMOD00270 - Laserfiche WebLink

Home Browse Search

During the 35 days of operation in May and June 2005 there were 16 flight days and 34 flights, including 11 research and 2 ferry flights by the Cheyenne cloud physics aircraft, 12 research and 2 ferry flights by the Cessna Ag Wagon salt seeder and 7 flightsby the Comanche reconnaissance aircraft. There were 7 salt experiments with monitoring by the cloud physics aircraft. During these experiments the expenditures of sized salt and SF6 gas were 556.4 kg and 59.2 kg, respectively. The SF6 gas was detected by the SF6 detector on the cloud physics aircraft during 3 of the 7 experiments and an apparent microphysical seeding signature was noted in the strongest updraft cases, specifically on May 25 and 31, 2005. A day-by-day summary of the SPECTRA-II flight activity is provided in Table 1. A substantial portion of project resources were used during the initial project period. The 40-hour allocation for flight of the base aircraft (Ag Wagon and Comanche) was used and a nearly 10 hour overage was paid for in Cheyenne flight hours on a 3:1 basis (i.e. 1 Cheyenne hour = 3 hours by the base aircraft. A net of about 18 hours Cheyenne flight hours remained for later use in SPECTRA-II. There were1,372 kg of sized salt and 61.1 kg of SF6 gas remaining on June 5, 2005. Thus, there weresufficient stores of flight hours, salt and gas to continue the SPECTRA II studies on a limited basis. At the end of the initial experimental period,the primary limitation of SPECTRA-II was its small sample of salt seeding experiments. The next step for SPECTRA-II is deployment to Pleasanton, Texas for the planned glaciogenic seeding experiments in which SF6 gas will be released in association with the burning of AgI flares at cloud base during o an operational seeding experiment. The cloud physics aircraft will then monitor the clouds between the -5C o and -10C levels for the SF6 gas in an attempt to document an ice seeding signature in the cloud regions where the gas is detected. 18