Evaluation of Water Vapor Product from TROPOMI and GOME-2 Satellites against Ground-Based GNSS Data over Europe

A novel integrated water vapor (IWV) product from TROPOspheric Monitoring Instrument (TROPOMI) is validated together with a Global Ozone Instrument-2 (GOME-2) standard product. As reference, ground-based Navigation Satellite Systems (GNSS) IWV data in 235 European stations May 2018 to 2019 are used. Under cloud free situations, general comparison carried out. It suggests that TROPOMI exhibits less bias than GOME-2 and better results the dispersion regression parameters. Moreover, presents more homogeneous along different stations. However, found be overestimating uncertainties being, therefore, too conservative confidence interval considered. The dependence of satellite performance on several variables also discussed. shows wet 5.7% or for < 10 mm dry up −3% (TROPOMI). In contrast, 30% 25 −12.3% > mm. addition, relative deviation (rSD) increases as increases. solar zenith angle (SZA) was analyzed, radiation bands used retrieval algorithm both instruments. Relative mean error (rMBE) positive values GOME-2, slightly increasing SZA, while stable values. under high steep increase rMBE (overestimation), moderate decrease (underestimation). rSD SZA. influence cloudiness observations such tends overestimate increases, especially IWV. case cloudiness, but has marked cloudiness. an important source information about moisture, its could still benefit further improvement respond cloudy situations.