An analysis of global climate variability from homogenously reprocessed GNSS measurements
Abstract:Over the last decade, Global Navigation Satellite Systems (GNSS) have emerged as a precise and cost-effective tool for studying the composition of the atmosphere. GNSS-derived information about tropospheric delay can be used for climate change and variability analysis on a global scale using homogeneously reprocessed GNSS solutions. At the University of Luxembourg, two such reprocessed global datasets of GNSS-derived zenith total delay (ZTD) and position estimates, covering 1994-2012, have been produced recently using the Bernese GNSS Software 5.2 and the reprocessed products from the Centre for Orbit Determination in Europe. One of these datasets is based on the network double differencing (DD) strategy whereas the other dataset is computed using precise point positioning (PPP). Both of these include over 400 GNSS stations and have been obtained using nearly identical processing settings. The two processing strategies, i.e. DD and PPP, each have their own strengths and weaknesses and could affect the solutions differently at different geographical locations.
The aim of this study is to evaluate the quality of the two GNSS-derived tropospheric delay datasets by comparing them to those derived from other techniques, e.g. radiosonde and Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) observations, as well as reanalysis data from, e.g. the European Centre for Medium-Range Weather Forecasts (ECMWF). Following this, we investigate inter-annual climate variability and trends in the tropospheric delay datasets on various regional to global spatial scales.