HR: 0800h
AN: ED31B-1211    [Abstracts]
TI: Using GPS radio occultation data in the study of tropical cyclogenesis
AU: * Didlake Jr., A C
EM: didlake@gmail.com
AF: Yale University, P.O. Box 208109, New Haven, CT 06520
AU: Kuo, Y B
EM: kuo@ucar.edu
AF: National Center for Atmospheric Research (NCAR), P.O. Box 3000, Boulder, CO 80307
AU: Metcalfe, T
EM: travis@ucar.edu
AF: National Center for Atmospheric Research (NCAR), P.O. Box 3000, Boulder, CO 80307
AB: Numerous studies have examined atmospheric conditions and patterns in tropical cyclogenesis. Although much has been accomplished, a complete understanding of tropical cyclogenesis is hindered by the lack of data in the regions where formation occurs. The GPS (Global Positioning System) radio occultation technique can provide valuable data in key areas. In GPS radio occultation, GPS satellites emit radio signals through the atmosphere that are received by another satellite in a low Earth orbit. Various atmospheric properties are calculated based on the alteration of the signal. This study assessed the value of GPS radio occultation data in the study of tropical cyclogenesis by examining storms of the 2002 Western North Pacific typhoon season. The signature of precursor disturbances to tropical cyclogenesis was determined by analyzing composites of data from the NCEP Aviation (AVN) analysis over four days. Similar composites of GPS radio occultation data were produced. The AVN analysis showed strong signals of precursor disturbances in the low-level wind fields and atmospheric refractivity. The GPS radio occultation data detected similarly increased refractivity values in corresponding regions, but had sizeable measurement differences with the AVN analysis. These differences were attributed to AVN analysis error due to the lack of input observational data and the high accuracy of GPS radio occultation measurements. Further comparisons showed that with the limited quantity of data currently available, GPS radio occultation by itself was not sufficient to detect precursor disturbances. It can best be used in data assimilation to improve the analysis and forecasts of tropical storms.
DE: 0800 EDUCATION
DE: 0810 Post-secondary education
DE: 0825 Teaching methods
DE: 0840 Evaluation and assessment
DE: 0845 Instructional tools
SC: Education and Human Resources [ED]
MN: Fall Meeting 2005