Update and validation of the onboard Jason-3 DEM for enhanced acquisitions over inland water targets

Sophie Le Gac (CNES, France)

CoAuthors

François Boy (CNES, France); Denis Blumstein (CNES, LEGOS, France); Augé Emmanuel (NOVELTIS, France); Sylvain Biancamaria (LEGOS, Université de Toulouse, CNRS, IRD, UPS , France); Jean-François Crétaux (CNES, LEGOS , France); Stéphane Calmant (LEGOS, Université de Toulouse, CNRS, IRD, UPS , France); Fabien Blarel (LEGOS, Université de Toulouse, CNRS, IRD, UPS , France); Frédéric Frappart (LEGOS, Université de Toulouse, CNRS, IRD, UPS , France); Charon Birkett (Earth System Science Interdisciplinary Center, University of Maryland-College Park (ESSIC/UMD), USA); Nicolas Picot (CNES, France)

Event: 2017 Ocean Surface Topography Science Team Meeting

Session: Science IV: 25 years of satellite altimetry for Cryosphere and Hydrology: from experimental to emerging operational applications

Presentation type: Type Oral

On Jason-3, data acquisition over inland water bodies is performed in either Diode/DEM mode or Autonomous Mode. For the first time, the altimeter tracking command is driven by the “mode bit” allowing switching automatically between these two modes [1].

From previous experience acquired on Jason-2 and SARAL/AltiKa, the DEM version generated for the launch of Jason-3 [2] included about 250 lakes from the Hydroweb database and a network of about 1500 virtual stations over rivers.
A global validation has been performed over the past year and has provided a very satisfying ratio of 95% successful acquisitions over lakes and 80% over rivers in DIODE/DEM mode.

In June 2016 (cycle 11 onwards), the onboard Jason-3 DEM was updated for taking into account a new additional network of 100 stations over France rivers. A subsequent validation work has been carried out [3] and has demonstrated that the altimeter is acquiring high quality measurements over all those virtual stations. Some river reaches have even been observed for the first time with an altimetry system thanks to the DIODE/DEM acquisition mode, including reaches that are only a few tens of meters wide. This study further validates the instrument behavior and demonstrates its capability to observe hydrological targets in this specific acquisition mode.

Building on this success, an update of the onboard DEM has been carried out in order to resolve the few remaining failures and expanding its coverage by including numerous new targets. This constitutes a great leap forward for Jason-3 DEM with a current total number of about 4350 river targets and 350 lakes.
We present details on this version of the DEM and illustrate its global validation, highlighting specific data cases over rivers and lakes.
We believe that the DEM quality and subsequent tracker performance is and will be of growing added-value to the hydrology community in preparation for SWOT.


[1] Desjonqueres et al., Jason-3/POS-3B First results, OSTST 2016.
[2] Augé et al., Performance analysis between autonomous tracker median and new version of OLTC mode, OSTST 2015.
[3] Biancamaria et al., Validation of Jason-3 tracking modes over French rivers, Rem. Sens. Env., submitted, 2017

 

Oral presentation show times:

RoomStart DateEnd Date
Symphony Ballroom IV Wed, Oct 25 2017,14:15 Wed, Oct 25 2017,14:30
Sophie Le Gac
CNES
France
sophie.legac@cnes.fr