Presenter: Ernesto Rodriguez (Jet Propulsion Laboratory/Caltech)

Description:
Recent advances in radar Doppler scatterometry have made global, simultaneous measurements of surface currents and winds from space feasible in the 2020's. This possibility has led to several mission concepts (SKIM, STREAM, WaCM) being examined by the air-sea interaction community during the past five years. These measurements would meet the measurement goals for the next decade outlined by the US NRC Decadal Survey for NASA (2017), complement the existing scatterometer/radiometer wind constellation, and provide total surface currents that, in conjunction with the geostrophic currents measured by the altimeter/SWOT constellation, would improve our understanding of unbalanced ocean-surface motions, vertical transports, and air-sea energy fluxes. The goal of these missions is to resolve short mesoscale and larger submesoscale motions (wavelengths < 30km) and dynamics that are driven by baroclinic instabilities, wind forcing, and tidal motions. Unlike missions that measure geostrophic currents, a careful balance must be achieved between spatial and temporal resolutions to sample the small spatial scales required to resolve current divergence and relative vorticity, while avoiding aliasing due to frontal weather systems, near-inertial oscillations (NIOs), and coherent and incoherent tides. High-resolution, coupled ocean-atmosphere models, such as the GEOS-MITgcm, play a crucial role in assessing the optimal configuration for a spaceborne mission, including orbit inclination, instrument swath, and the trade between spatial resolution and random measurement noise. Here, we will present the results of simulations for various configurations of a potential WaCM mission and show their ability to resolve regional surface current dynamics, including divergence and relative vorticity, wind-work, NIOs, and tides. Also examined will be sampling schemes that complement the existing wind and altimetry/SWOT constellations that would be present at the time of a WaCM mission.