A high‐quality reprocessed ground‐based GPS dataset for atmospheric process studies, radiosonde and model evaluation, and reanalysis of HyMeX Special Observing Period

Abstract

A special screening procedure is developed for the removal of outliers in the GPS Zenith Total Delay (ZTD) data. ZTD data are converted to integrated water vapour (IWV) using surface pressure information from an AROME-WMED operational analysis. The reprocessed ZTD and IWV data are used to assess the accuracy of the near-real time E-GVAP ZTD data assimilated in operational numerical weather prediction systems and to validate the IWV data from the AROME-WMED operational analysis and AROME-WMED reanalysis 1, and from radiosonde observations. The mean differences between E-GVAP and reprocessed ZTD data are not negligible and lie in the range from −3 to +3 mm. The standard deviations of differences are between 4 and 8 mm. The comparisons of IWV from AROME-WMED analyses and the reprocessed GPS data show high quality of the analyses where operational GPS data are assimilated and lower quality where no GPS data are assimilated. Small but significant biases are found in the radiosonde data during daytime (−0.5 to +1.4 kg m −2 ), but their origin is not determined so far. Thanks to the high spatial density of the reprocessed GPS stations, both the large-scale and small-scale variations in IWV can be documented. The case of HyMeX Intensive Observing Period 8 is presented as an example of a heavy precipitation event. This work suggests that improved quality of the humidity fields can be expected of the future AROME-WMED reanalysis 2 as a result of the assimilation of the reprocessed GPS data.

EPN-Repro2: A reference GNSS tropospheric data set over Europe

“…The Working Group 3 enforces the cooperation between geodesists and climatologists in order to generate recommendations on optimal GNSS reprocessing algorithms for climate applications, and to standardise the conversion method between propagation delay and atmospheric water vapour for these applications (Saastamoinen, 1973;Bevis et al, 1992;Bock et al, 2016). For climate applications, maintaining long-term stability is a key issue.…”

GPS – Zenith Total Delay assimilation in different resolution simulations of a heavy precipitation event over southern France

“…The model data employed in this study are property of the hosting research institution and are not publicly available. The GPS-derived datasets for ZTD and IWV are provided the LAboratoire de Recherche en Géodesie (LAREG) as part of L'Institut National de L'Information Géographique et Forestière (Bock and Bosser, 2014). The high-resolution satellite precipitation data set is provided by the Climate Prediction Center/National Centers for Environmental Prediction/National Weather Service/NOAA/U.S.…”

“…1) is continuously assimilated during the three-day simulation period with a frequency of 10 min. This data set is provided by the Institut National de L'Information Géographique et Forestière (IGN; Bock et al, 2016) and has been specially homogenized for 25 European GPS networks as a contribution to the HyMeX community. Therefore, simulations (hereafter referred to as AS) are obtained by assimilating only GPS-ZTD data by means of the Nudging towards observations method (Schraff and Hess, 2012) using the operational nudging parameters employed at the German Weather Service (DWD).…”

A Raman lidar at Maïdo Observatory (Reunion Island) to measure water vapor in the troposphere and lower stratosphere: calibration and validation

“…The hydrostatic delay, which is derived by applying the condition that hydrostatic equilibrium is satisfied, depends on the total weight of the atmosphere above. The difference term accounts for the microwave radiometers, lidars and interferometers (Foelsche and Kirchengast, 2001;Niell et al, 2001;Bock et al, 2016).…”