An investigation of atmospheric temperature profiles in the Australian region using collocated GPS radio occultation and radiosonde data

摘要

GPS radio occultation (RO) has been recognised as an alternative atmosphericupper air observation technique due to its distinct features andtechnological merits. The CHAllenging Minisatellite Payload (CHAMP) ROsatellite and FORMOSAT-3/COSMIC (Constellation Observing System forMeteorology, Ionosphere and Climate) RO constellation together have providedabout ten years of high quality global coverage RO atmospheric profiles.This technique is best used for meteorological studies in thedifficult-to-access areas such as deserts and oceans. To better understandand use RO data, effective quality assessment using independent radiosondedata and its associated collocation criteria used in tempo-spatial domainare important. This study compares GPS RO retrieved temperature profilesfrom both CHAMP (between May 2001 and October 2008) and FORMOSAT-3/COSMIC(between July 2006 and December 2009) with radiosonde data from 38Australian radiosonde stations. The overall results show a good agreementbetween the two data sets. Different collocation criteria within 3 h and300 km between the profile pairs have been applied and the impact of thesedifferent collocation criteria on the evaluation results is foundstatistically insignificantly. The CHAMP and FORMOSAT-3/COSMIC temperatureprofiles have been evaluated at 16 different pressure levels and thedifferences between GPS RO and radiosonde at different levels of theatmosphere have been studied. The result shows that the mean temperaturedifference between radiosonde and CHAMP is 0.39 °C (with a standarddeviation of 1.20 °C) and the one between radiosonde andFORMOSAT-3/COSMIC is 0.37 °C (with a standard deviation of 1.24 °C).Different collocation criteria have been applied and insignificantdifferences were identified amongst the results.