The next step in marine reference surfaces – the DTU25 mean sea surface

During the last 30 years, following the breakthrough that was the TOPEX/Poseidon satellite altimeter, improvements of satellite altimetry has been incremental. We have several generations of satellites to build upon, and with the inclusion of SAR processing, we are reaching the limit of conventional satellite altimetry. With the breakthough that is the Surface Water and Ocean Topography (SWOT) mission, we are able to significantly imrpove our knowledge of ocean geodesy, and provide greatly improved references for oceanography and climate research.

The importance of an accurate mean sea surface reference for global climate science, sea level rise and coastal impacts have been shown. With the inclusion of two-dimensional satellite altimetry, we go beyond the limitations obtained from nadir looking altimetry. With the 2D data, the longitudional resolution is substantially improved, and we have seen a substantial improvement in especially coastal zones, eliminating the majority of coastal contamination causing problems in current models.

With almost two years of SWOT data available, we have a near complete global coverage. Longer wavelengths are alreay well resolved with the 30 years of conventional altimetry, and utilizing the short-wavelength improvement obtained from SWOT, we can get a combined solution with the best from both sides.

We present the next generation of mean sea surface reference fields, with major improvements in spatial resolution and noise reduction. The inclusion of SWOT data has shown small scale oceanographic features previously hidden, and will be of critical importance for geodesy, oceanography and climate science.