|dc.description.abstract||By using the radio occultation (RO) technique, high resolution atmospheric sounding variables can be retrieved from the very accurate Global Positioning System (GPS) measurement and eventually provide a real time climate monitoring. After FORMOSA-3 launched on April 15, 2006, a sequential assimilated data generated by CWB/GFS-3DVAR global assimilation system are utilized to investigate the impact of GPS RO data on the climate study and analysis. To examine the advantage of using GPS RO data, NCEP analysis data are also adapted to serve a cross comparison purpose.
The basic atmospheric circulation structure and standing waves are properly captured by CWB/GFS-3DVAR assimilation system with and excluding GPS RO data. However, the major differences appear in both tropics and subtropical regions, especially over the ocean. The estimated statics in terms of variance ratio for each atmospheric variable, in general, are less than 10 % with comparison between with and excluding GPS RO results. Furthermore, the variation shows more significant over the ocean in Southern than Northern hemisphere indicates that GPS RO data have some sort of impact on the climate study.
Due to the GPS receiver firmware upgraded for fixing the data retri-
eval problem in late July, the latitude-height zonal cross section for each atmospheric variable shows significant variation in August then in June and July. Again, the prominent differences appear in the vast ocean occu-
pied Southern hemisphere with GPS RO data. Another possible reason to cause relatively significant variation in Southern hemisphere might be contributed from the mid-latitude cyclone activities during Southern win-
ter time. A further examination is along the line on the process.
Finally, the primary results from the hydrological analysis also demonstrate that GPS RO data have some influences on global water vapor transport and budget analysis. It also shows that the major impact mainly appear in the tropic and subtropical ocean area.||en_US|