Two Decades of GNSS Integrated Water Vapour in the SIRGAS Network

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Abstract The SIRGAS-CON network has computed hourly tropospheric parameters over America since 2014. Currently, the zenith total delay (ZTD) has been recovered from 2002 due to the reprocessing of historical network data referred to IGS14. This work presents the methodology for validation of the integrated water vapour (IWV) from the SIRGAS ZTD, using radiosonde (RS) measurements. This comparison was made for 101 SIR sites (16% of the whole network), considering sites with a maximum distance of 35 km and a minimum of 3 years of observations in common. Quality control procedures were applied to the IWV time series to detect outliers and possible errors in the data. Results indicate that for 98% of the stations, the correlation between IWV estimations and observations was r > 0.91 ( p < 0.01), with a mean absolute difference of 0.62 kg/m 2 . This work highlights the potential of GNSS-based IWV to overcome data gaps in radiosonde records, especially over Latin America and the Caribbean, and to complement satellite-based estimations which often face inhomogeneities due to instrumental changes.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.