Publications

Spaceborne GPS radio occultation sounding of the Earth's atmosphere is regarded as a highly accurate measurement technique for the remote sounding of stratospheric temperature and tropospheric humidity profiles. In this study, we describe the validation of GPS/MET data during the A/S off period in February 1997. The meridional structure of deviations between GPS/MET temperatures and several meteorological analyses of the stratosphere show a complex structure, reflecting some shortcomings of the analyses. However, radio occultation measurements exhibit a significant warm bias at low temperatures relevant for Polar Stratospheric Cloud formation at and above the 30 hPa level. Global humidity fields at the 500 hPa level obtained from GPS/MET soundings during the same period are also compared with analysis data. While GPS/MET soundings highlight known deficiencies in the analyses' tropical moisture budget, large relative errors of more than 50% in specific humidity are caused by uncertainties in ancillary temperatures used in the retrieval of humidity in mid and high latitudes.

---

Marquardt, C.; Labitzke, K.; Reigber, C.; Schmidt, T.; Wickert, J. (2001): An Assessment of the quality of GPS/MET radio limb soundings during February 1997. Physics and Chemistry of the Earth (A), 3, 26, 125-130.