Global positioning systems meteorology over Morocco: accuracy assessment and comparison of zenith tropospheric delay from global positioning systems and radiosondes

Abstract

Global positioning systems (GPSs) have become a powerful remote sensing tool to estimate the water vapour in the troposphere. This study describes the operational processing of the Moroccan ground-based GPS meteorology stations. It presents the evaluation of the accuracy of zenith tropospheric delay (ZTD). The accuracy is evaluated first in relation to the International Global Navigation Satellite System Service (IGS) final products, and second by comparison to equivalent values derived from radiosonde profiles. The comparison of near-real-time ZTD with the IGS final product shows a bias of −1 mm with a standard deviation of 6 mm. The comparison with radiosondes shows a bias of −2.82 mm and a standard deviation of 14.01 mm. Also, the comparison of GPS ZTD and radiosonde ZTD time series over almost 1 year (2016) shows good agreement and a seasonal signal with higher values of ZTD in summer.