Atmospheric profiles can be retrieved with techniques utilizing measurements of the propagation delay of signals from Global Positioning System (GPS) satellites observed by one or more receivers in low earth orbit. The. observations are made in a limb-sounding geometry when the radio path between the transmitter and receiver passes through the atmosphere. The various componen~s of the microwave...

A major challenge for operational numerical weather prediction over the Antarctic and Southern Ocean is the lack of traditional meteorological observations. This increases uncertainty in the model initial condition and results in inferior forecast skills as compared with numerical weather prediction in mid-latitudes over the Northern Hemisphere. With the lack of traditional observations over th...

[1] We survey the IPCC AR4 models’ responses to SRES A1B forcing in order to evaluate a prediction of climate change common to all models and testable using GPS radio occultation data over the coming decades. Of the IPCC AR4 models that submitted runs of the SRES A1B forcing scenario, we select twelve because of the timeliness of their submission. Trends in the global average surface air temper...

[1] An ionosphere has been detected at Callisto by the Galileo spacecraft, using the radio occultation technique. There were four usable occultations by Callisto, providing eight observation opportunities, all equatorial and near the terminator (entry and exit observations). Detectable electron densities were obtained from six of the eight opportunities. It was found that a detectable ionospher...

Elimination of the ionospheric contribution to atmospheric delays in GPS radio occultation measurements is a key issue in the retrieval of accurate pressure and temperature profiles above the tropopause. The traditional so-called “ionosphere-free” combination of the L1 and L2 phase paths, eliminating the first-order ionospheric effects, is not sufficient because of the nonnegligible bending of ...