Calculating the differences of VTEC values obtained by altimetric and GNSS observations in coastal areas

The difference between the VTEC values obtained from the Global Navigation Satellite System (GNSS) and satellite altimetry is much more noticeable over the ocean and the sea due to less coverage of the GNSS observations. Previous research shows that differences can go up to 15 TECU. The main problem is calculating VTEC from raw data which is ambiguous. This paper presents filtering methods for estimating the differences between mentioned datasets. By using this solution, it is possible to achieve better accuracy on a global estimation of the deviation. The International Reference Ionosphere values were used for validation of the results.