Wet tropospheric correction for satellite altimetry using SIRGAS-CON products

The wet tropospheric correction (WTC) is a required correction to satellite altimetry measurements, mainly due to the atmospheric water vapor delay. On-board microwave radiometers (MWR) provide information for WTC estimation but fail in coastal zones and inland waters. In view to recover the WTC in these areas, the Global Navigation Satellite System (GNSS)-derived Path Delay Plus (GPD+) method, developed by the University of Porto, uses Zenith Tropospheric Delays from GNSS global and regional networks' stations combined with other sources of information, providing a WTC solution for all along-track altimeter points. To densify the existing dataset used by GPD+, it is necessary to add new GNSS stations, mainly in the southern hemisphere, in regions such as South America, Africa and Oceania. This work aims to exploit the SIRGAS-CON data and its potential for densification of the GPD+ input dataset in Latin America and to improve GPD+ performance. The results for the three analyzed satellites (Sentinel-3A, Sentinel-3B and CryoSat-2) show that, when compared with the WTC from GNSS and radiosondes, the densified GPD+ WTC leads to a reduction in the RMS of the WTC differences with respect to the non-densified GPD+ solution, up to 2 mm for the whole region and up to 5 mm in some locations.

Automated summary

The wet tropospheric correction (WTC) is a necessary correction for satellite altimetry measurements to account for the delay caused by atmospheric water vapor. The current method using on-board microwave radiometers (MWR) is not effective in coastal zones and inland waters, prompting the development of a new method. This study proposes a new WTC solution using GNSS data and other sources of information, and demonstrates its improved performance through densification of the input dataset using SIRGAS-CON data, achieving a reduction of up to 2 mm for the whole region and up to 5 mm in some locations.