The Surface Water and Ocean Topography (SWOT) altimeter mission will have the capability to map sea surface height in two-dimensions and with higher spatial resolution than is achieved by existing nadir altimeters.
SWOT will offer significant new research opportunities in regions of the world characterized by small-scale mesoscale and sub-mesoscale variability, particularly coastal regions and high-latitude regions, such as the California Current and Southern Ocean. This contribution to the SWOT Science Definition Team (SDT) is aimed at articulating requirements for measuring mesoscale (and sub-mesoscale) variability, particularly in the Southern Ocean and the California Current system. Using existing satellite and in situ observations and taking advantage of regional 4-D variational state estimates will enable examination of the physical processes that may complicate interpretation of the SWOT signal in problematic coastal and high-latitude regions. In the Southern Ocean, where mean winds are among the strongest in the world, the sea-state bias remains a lingering concern in existing altimeter products, and it will need to be refined to make full use of SWOT data.
Atmospheric properties can change rapidly over the land-sea interface in coastal regions and over small-scale eddies in both coastal and high-latitude regions. These small-scale atmospheric variations are not captured in existing numerical weather prediction products that are used to correct satellite altimeter data, but they will need to be taken into account to obtain high-quality small-scale results from SWOT. AirSWOT measurements planned over the California Current will be a valuable resource for assessing SWOT instrument performance and requirements, and these data will also provide a valuable point of comparison with our ongoing California Current Ocean State Estimate. Our objective in contributing to the SWOT SDT is to help ensure that SWOT will provide a data product that is well suited for studying mesoscale eddy processes and for use with eddy-resolving ocean state estimation.