VarDyn: Dynamical Joint-Reconstructions of Sea Surface Height and Temperature From Multi-Sensor Satellite Observations

The VarDyn hybrid methodology, which combines minimal physically based constraints with a variational scheme, is demonstrated to enhance the mapping of sea surface height (SSH) and sea surface temperature (SST). By synthesizing multi-modal satellite observations, VarDyn produces SSH and SST maps with improved accuracy compared to operational products, achieving reductions in Root Mean Square Error and enhancements in effective spatial resolution. While most improvements are observed in highly energetic ocean regions, SSH map accuracy also improves slightly in low-energy regions—a significant advancement over other methods. VarDyn SSH fields and the associated geostrophic velocities show strong agreement with newly available high-resolution instantaneous SWOT estimates. Notably, the assimilation of SST proves particularly beneficial for SSH reconstruction when only two altimeters are available. The VarDyn methodology potentially offers a robust framework for refining climate SSH records by jointly assimilating SSH data from two altimeters and SST data from microwave sensors.