Atmospheric Precipitable Water in Somma-Vesuvius Area During Extreme Weather Events from Ground-Based GPS Measurements

In this paper, we analyze the tropospheric delay observed on some ground-based CGPS stations in a dense small regional network and its time evolution during extreme weather conditions. In particular, we studied two severe weather events occurring in the Campanian Region (Italy) on October 12, 2012 and December 2, 2014, reaching 42 and 28 mm rainfall during about 1 h at Naples (MAFE) and Gragnano (GRAG) stations respectively. The main concern of this study is the retrieval of the precipitable water (PW) from co-located GPS and meteorological stations. We investigate the correlation between PW and rain amount at ground level. We analyse phase residuals for each visible GPS satellite using sky plots of the phase residuals along the GPS satellites tracks, showing that the two phenomena are shown in the phase residual plots. Moreover, we compare PW data retrieved from observed meteorological data and from models (GPT2 and ECMWF), evidencing that there is a need for co-located CGPS and weather stations to improve the assessment of water content in the troposphere.