CoAuthors

Eric Leuliette (NOAA Laboratory for Satellite Altimetry , USA); John Lillibridge (NOAA Laboratory for Satellite Altimetry , USA)

The Poseidon-3 altimeter onboard Jason-2 includes a significant new capability with respect to its predecessors, a CNES-developed open-loop (DIODE/DEM) tracking mode that allows for maintaining data acquisition over coastal and inland water [1]. In a further enhancement, Jason-3 and Sentinel-3 will be capable of switching to DIODE/DEM mode for selected regions. In order to recommend how these missions should operate DIODE/DEM, we have studied the impact of the tracking modes on the accuracy of wave heights and wind speed, on the continuity of climate data record in sea level measurements, and the coverage of coastal regions.
Since its launch in 2008 Jason-2 has operated in DIODE/DEM for only a few cycles: 0 (partial), 3, 5, 7, 34, 209, and most recently 220. For this study we mainly concentrate on those cycles after commissioning: cycles 34, 209, and 220. Our work primarily concentrates in the statistical performance analysis of the main geophysical retrievals of altimetry. While proving enhancements as in [1] we've identified differences between open-loop and closed-loop modes in the statistical behavior of a few geophysical retrievals that deserve to be presented and further investigated.
A summary of the main achievements and recommendations for Jason-3 and Sentinel-3A CAL/VAL planning will be presented.

[1] J.D. Desjonquères, G. Carayon, N. Steunou and J. Lambin. 'Poseidon-3 Radar Altimeter: New Modes and in-flight performances', Marine Geodesy, 33 (s1): 53-59, 2010.

Keywords: DIODE/DEM, Tracker, Poseidon-3, Jason-2, Jason-3, Sentinel-3A, altimetry