Feasibility of estimating sea surface height anomalies from surface ocean currents and winds

We propose a method to reconstruct sea surface height anomalies (SSHA) fromvector surface currents and winds. This analysis is motivated by the proposed satellite ODYSEA,which is a Doppler scatterometer that measures coincident surface vector winds and currents. If it isfeasible to estimate SSHA from these measurements, then ODYSEA could provide collocated fieldsof SSHA, currents, and winds over a projected wide swath of ∼1700 km. The reconstruction alsoyields estimates of the low-frequency surface geostrophic, Ekman, irrotational and non-divergentcurrent components and a framework for separation of balanced and unbalanced motions. Thereconstruction is based on a steady-state surface momentum budget including the Ekman drift,Coriolis acceleration, and horizontal advection. The horizontal SSHA gradient is obtained as aresidual of these terms, and the unknown SSHA is solved for using a Helmholtz-Hodge Decomposition given an imposed SSHA boundary condition. We develop the reconstruction using surfacecurrents, winds, and SSHA off the U.S. west coast from a 43-day coupled ROMS/WRF simulation. We also consider how simulated ODYSEA measurement and sampling errors and boundarycondition uncertainties impact reconstruction accuracy. We find that temporal smoothing of thecurrents for periods of 150 hours is necessary to mitigate large reconstruction errors associated withunbalanced near-inertial motions. For the most realistic case of projected ODYSEA measurementnoise and temporal