Cross Validation of Water Vapour Retrievals from Ground Based GPS and Satellite Radiometric Measurements over Antarctica

Abstract. Water vapour distribution plays a key role in the Antarctic precipitation pattern. Due to the extreme climate conditions and the sparse number of research stations, the number of meteorological records from Antarctica is limited. Satellite radiometric measurements and ground-based GPS measurements can therefore improve the amount of available water vapour data. Combining the zenith total delay (ZTD) time series from 6 Antarctic GPS stations and surface meteorological data we determined precipitable water vapour (PW) variations with a 2h temporal resolution for a period of 5 years. Data of the Advanced Microwave Sounding Unit AMSU-B on board the NOAA-15 satellite cover most parts of Antarctica but with observations limited to merely few times a day. GPS and AMSU-B datasets are therefore complementary with respect to time and space. We present a comparison between PW results from the two independent retrieval algorithms using one year of data. GPS and AMSU-B water vapour estimates are highly correlated and show a low standard deviation of about 0.8 mm. The mean differences between both datasets are station dependent and vary from-0.7 to +1.3 mm. GPS and AMSU-B as independent data sources are confirmed to be accurate methods for PW estimation for the dry Antarctic atmosphere