Validation of Jason-2 coastal retrackers using high frequency radar surface currents on the US west coast

Carolyn Roesler (University of Colorado at Boulder, United States)


William Emery (University of Colorado at Boulder, United States); Robert Leben (University of Colorado at Boulder, United States)

Event: 2014 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and retracking (SAR and LRM)

Presentation type: Type Poster

The High Frequency Radar (HFR) network on the US West coast spans the entire California region. The California Current system is a dynamic region with a rich eddy field and makes it a perfect laboratory to analyze the relationship between the altimeter and HFR measurements. In about 40% of the cases the estimated geostrophic current anomalies derived from HFR coastal surface currents match the ones estimated from 1-Hz along track altimetry. Although, the exact conditions required for the fit are not completely understood, it depends strongly on the wind history.

The new application concerns the validation of the retracking techniques along an altimeter track, instead of sparse point validation measurements from tide gauges or current meters, and provides continuity between the open ocean and coastal altimeter Sea Surface Height (SSH) retrievals. The inferred geostrophic HFR field can be used as a validation reference, as long as there are sufficient collocated SSH valid measurements on the altimeter track, so that the quality of the HFR geostrophic data can be estimated.

The California Bight provides some Jason-2 tracks where the altimeter passes between or over islands located 40 km offshore. These are very promising locations to further develop this methodology, test several dedicated coastal retrackers and validate them by referencing to the HFR geostrophic field. Also once the conditions for a consistency between the HFR and altimeter data are established, the two dimensional surface current map generated by the HFR would be invaluable for the validation of the future Surface Water and Ocean Topography (SWOT) mission.

Carolyn Roesler
University of Colorado at Boulder
United States