Comparing GPS radio occultation observations with radiosonde measurements over Antarctica

GPS Radio Occultation (RO) is a space-based technique for sounding the Earth's atmosphere. This technique has been shown to significantly improve weather forecasting and climate monitoring over many regions of the Earth. The GPS RO technique uses specially-designed GPS L-band frequency receivers on-board Low Earth Orbit (LEO) satellites to receive signals from GPS satellites. The Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) is a joint Taiwan and USA satellite program and was launched into orbit in April 2006. GPS RO data from this constellation of six FORMOSAT-3 (Formosa Satellite Mission #3), LEO (800 km altitude) micro-satellites provide an observational data type for operational meteorology and significant information on the thermodynamic state of the atmosphere. In the Antarctic region there are only 16 radiosonde (RS) weather stations mainly distributed along the coastal fringe. As such this RS network is far from ideal for studying the atmosphere, meteorology and climatology in the Antarctic region. It does however provide excellent reference stations to test and validate the GPS RO technique as a suitable meteorological data type in the Antarctic region. In this study the COSMIC GPS RO temperature and pressure profiles are compared to those measured using radiosondes in the Antarctic region. Annual area weighted average temperature profiles from the Antarctic region are presented.