Temperature and water vapor profiles derived from downward-looking GPS occultation data

Downward-looking (DL) Global Positioning System (GPS) occultation experiments from the top of Mt. Fuji were carried out as a joint project between Kyoto University, Meteorological Research Institute in Japan, and the Jet Propulsion Laboratory (JPL) in the U.S.A. from July 10 to September 25, 2001, in order to obtain temperature, water vapor and pressure profiles near the Earth's surface. A TurboRogue SNR-8000 GPS receiver and a choke ring antenna were installed at the Mt. Fuji weather station located at an altitude of about 3.8 km. Applying an Abel inversion, these DL observations can provide refractivity profiles over an area south of Mt. Fuji. This paper shows temperature, relative humidity, and pressure profiles derived from these refractivity profiles using a one-dimensional variational technique (1D-Var). The derived profiles show agreement with the Mt. Fuji weather station observations within 1.7 degreesC, 1.2%, and 1.0 hPa at the receiver altitude.