While spatial data for sea surface salinity, sea surface height, and significant wave height exist (Ex.  ), I've not been able to find spatial mean squared slope data, or wave spectrum data (from which mean squared slope can be derived). The only data I know of are from the National Buoy Data Center, but they are point measurements only.
I'm currently working on a microwave remote sensing project, and spatial mean squared slope data would prove to be helpful. Does anyone know if spatial mean squared slope or wave spectrum data exist anywhere?