Linking Conventional and SAR Altimetry with Cryosat-2: An assessment over the whole mission

Sylvie Labroue (CLS, France)

CoAuthors

Matthias Raynal (CLS, France); Thomas Moreau (CLS, France); Annabelle Ollivier (CLS, France); Philippe Schaeffer (CLS, France); François Boy (CNES, France); Nicolas Picot (CNES, France)

Event: 2014 Ocean Surface Topography Science Team Meeting

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

Presentation type: Type Oral

Cryosat-2 is ESA's ice mission which primary objective is to serve Cryosphere science. Nevertheless, Cryosat-2 has, in theory, the potential to be a mission of opportunity for oceanography. Indeed, the satellite embarks an innovative radar altimeter, and high-precision orbit determination (POD), which are expected to be at least as accurate as ENVISAT's.

Even if Cryosat-2 is not an optimised payload for mesoscale observation (no radiometer and single frequency altimeter, no repetitive ground track), Labroue et al. (2011) and Scharoo et al. (2012) showed that the Cryosat-2 system gives very good performance in its traditional mode (Low Resolution Mode).

The Cryosat-2 altimeter is operated almost continuously over ocean, either in Low Resolution Mode (like conventional pulse-limited altimetry sensors) or in the so-called Delay Doppler/SAR mode (higher-resolution and lower noise level). Boy et al (2012, 2013) developed dedicated SAR retracking processing and showed that the results obtained over a full year of data were very promising. On the one hand, this technique appears to be mature enough to replace LRM mode in order to retrieve mesoscale signal. On the other hand, very compelling results have been obtained in the shortest scales below 80 km where the SAR provides more accurate data.

The geodetic orbit with a cycle of 369 days coupled with the noise reduction on SAR data makes Cryosat-2 data set very attractive for the improvement of the mean sea surface. The data quality of the mission has been assessed on the extended CPP SAR time series through different metrics that are presented here. We analyse more deeply the main features to check the reliability and the improvements of the SAR processing (noise reduction, increased along track spatial resolution, check of the dependencies that may induce geographically correlated errors...). A focus is done on the continuity between LRM and SAR processing to provide a seamless transition between both kinds of observations.
 

Oral presentation show times:

RoomStart DateEnd Date
Red salon Thu, Oct 30 2014,10:00 Thu, Oct 30 2014,10:15
Sylvie Labroue
CLS
France
sylvie.labroue@cls.fr