Comparison of tropospheric parameters from Meteodrone measurements with GNSS estimates from ground-based stations

Abstract

This study presents a comparison of tropospheric parameters, namely zenith tropospheric delay and total refractivity calculated using meteorological measurements from a Meteodrone and Global Navigation Satellite Systems (GNSS) stations. A Meteodrone is a unique Unmanned Aerial Vehicle (UAV) originally designed for automatic measurements of meteorological parameters in vertical profiles (up to 3 km above ground) for the assimilation into numerical weather prediction models. One profile measured with both ascending and descending drone takes approximately 20 min, and there are multiple flights possible during one night. The measurements for this campaign have been conducted in March 2019, in Marbach, Switzerland. We have collected pressure, temperature and humidity profiles from nine flights. From the measured meteorological parameters, we have calculated the refractivity and zenith tropospheric delays (ZTDs). The parameters are compared with models calculated from 32 neighboring GNSS stations interpolated using the in-house developed least-squares collocation software COMEDIE (COllocation of MEteorological Data for Interpretation and Estimation of tropospheric path delays). The comparisons between the Meteodrones and the GNSS-derived models show a good agreement with an average absolute bias of 2.4 mm with 1.5 mm standard deviation for ZTD and 2.7 ppm with 1.7 ppm standard deviation for the comparison of the refractivity. The bias is a result of local changes of meteorological conditions captured by the drone, but not by the interpolation model.