Tropospheric delay performance for GNSS integrated water vapor estimation by using GPT2w model, ECMWF's IFS operational model and in situ meteorological data

摘要

Tropospheric delay comprises one of the most important error sources insatellite navigation and is caused when radio signals broadcasted by GPSsatellites propagate into the atmosphere. It is usually projected onto zenithdirection by using mapping functions named as Zenith Tropospheric Delay(ZTD). ZTD is described as the sum of the Zenith Hydrostatic Delay (ZHD) andthe Zenith Wet Delay (ZWD) and with the aid of surface pressure andtemperature the integrated water vapor can be estimated. The main objectiveof this study is to evaluate the tropospheric delay performance for GNSSintegrated water vapor estimation by using GPT2w model, ECMWF's IFS (ECMWFstands for the European Centre for Medium-Range Weather Forecasts) reanalysismodel and ground meteorological data from two stations of the permanentnetwork of Cyprus and Greece. The period from 27 May to 3 June 2018 ischaracterized by two different synoptic conditions: high pressure with fairweather in central Mediterranean (Greece), on the one hand, and highinstability over the upper levels of the atmosphere that resulted inthunderstorms inland and mountainous areas during midday over the EasternMediterranean (Cyprus), on the other hand. In general, the results show thatboth the empirical blind model GPT2w and the ECMWF (IFS) operational modelperform well in particular over Nicosia when used for the retrieval ofIntegrated Water Vapor (IWV) from GNSS measurements, although appreciabledeviations were observed between ECMWF (IFS)-retrieved IWV and the oneretrieved from GNSS observations by using meteorological measurements. Asharp increase of IWV prior to the abrupt rainfall events during noon on 30 and 31 May over Nicosia was also found.