Potential use of HF radar and SAR velocities for regional High Resolution Mean Dynamic Topography Estimation

Marie-Helene Rio (CLS, France)


Claire Dufau (CLS, France); Romain Husson (CLS, France); John Wilkin (Institute of Marine and Coastal Sciences, Rutgers, USA); Alexis Mouche (Ifremer, France); Emilie Bronner (CNES, France)

Event: 2014 Ocean Surface Topography Science Team Meeting

Session: The Geoid, Mean Sea Surfaces and Mean Dynamic Topography

Presentation type: Type Poster

Strong improvements have been made in our knowledge of the Ocean Mean Dynamic Topography at spatial scales down to 125 km thanks to the use of the latest GOCE geoid model. This estimate can be improved at short scales, as has been recently done for computing the global 1/4° CNES-CLS13 MDT (Rio et al, 2013) by taking advantage of in-situ measurements of the ocean surface velocities and dynamic heights by drifting buoys and Argo floats. However, in strong currents and in coastal areas, higher resolution field is needed for the optimal exploitation of the altimeter data, in particular for its assimilation into operational forecasting systems. This is all the more needed in the prospect of the upcoming SWOT satellite, which will measure the sea level at very high spatial resolution (1 km).
In order to improve regionally the resolution of existing MDT solutions, we investigate the feasibility of using high resolution velocity measurements of the ocean surface currents from two observing systems: On one hand, we analyze the potential contribution of a network of radar HF hourly, 6 km resolution velocity measurements available for the Mid Atlantic Bight area for the period 2006-2014. On the other hand, the impact of using the Doppler velocities from ENVISAT SAR images over the period 2007-2012 in the Agulhas Current area is investigated. In both cases velocity data are analyzed and compared to altimeter data in term of physical content and resolved spatial scales and recommendations for their potential use for high resolution regional MDT calculation are provided.
Marie-Helene Rio