A Seamless Transition Between LRM and SAR Altimetry: 3 Years Dataset Assessment of Cryosat-2 SARM

Matthias Raynal (CLS, France)

CoAuthors

Sylvie Labroue (CLS, FRANCE); Thomas Moreau (CLS, FRANCE); Laiba Amarouche (CLS, FRANCE); Francois Boy (CNES, France); Nicolas Picot (CNES, France)

Event: 2015 Ocean Surface Topography Science Team Meeting

Session: Regional and Global CAL/VAL for Assembling a Climate Data Record

Presentation type: Type Poster

The ESA (European Space Agency) mission Cryosat-2 was successfully launched on April 2010. The Cryosat-2 altimeter radar differs from previous conventional pulse limited altimeter in that it is capable of operating in several modes. The low resolution mode (LRM) is used over Antarctic and Greenland interiors and over the ocean. To better detect transitions between the open Ocean and land ice sheets, the Synthetic Aperture Radar mode (SARM) is used, since it provides a better along-track resolution (around 300 m). Finally, over land ice sheet margins, the Synthetic Aperture Interferometric mode (SARInM) provides more information with an interferometric across-track operation to estimate the arrival angles of the echoes.

As part of the Sentinel-3 project, the “Centre National d’Etudes Spatiales” (CNES) has developed a Cryosat-2 Processing Prototype (CPP) (Boy et al 2012, 2013). This processor starts from Cryosat-2 level-0 telemetry files and generate Sea Level Anomaly (SLA) measures for each record in LRM or SAR mode.

The present study shows some results obtained on a longer time series with a three year CPP SAR data record. This data set represents a major achievement in the understanding of the SAR mode altimetry (Raynal et al in prep). Data quality has been assessed 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, continuity with LRM processing...).

All these efforts will result in achieving a seamless transition between LRM and SAR altimetry techniques and fulfilling the operational needs for assimilating sea level in operational forecast models. On the other hand, the Sentinel-3 SAR mode observations of sea level shall provide for the first time at global scale a data record with an improved accuracy, paving the way for high resolution altimetry and for a better observation of small scale ocean dynamics.

 

Poster show times:

RoomStart DateEnd Date
Grand Ballroom Foyer Thu, Oct 22 2015,11:00 Thu, Oct 22 2015,18:00
Matthias Raynal
CLS
France
mraynal@cls.fr