Evaluating the performance of JASON and ENVISAT satellite altimeter missions at detecting prior errors in eddy-resolving ocean models.

Pierre Brasseur (CNRS/LGGE, France)

CoAuthors

Adeline Bichet (CNRS/LGGE, France); Jean-Michel Brankart (CNRS/LGGE, France); Pierre-Antoine Bouttier (CNRS/LGGE, France)

Event: 2015 Ocean Surface Topography Science Team Meeting

Session: Others (poster only)

Presentation type: Type Poster

In this poster we compare the capacity of different satellite missions at detecting prior simulation errors in ocean circulation models. The methodology used to quantify the gain in information brought by the satellite data flow is inspired from the Representer Matrix Spectrum (RMSpectrum) method (Le Hénaff et al. 2009). Given an assimilation system based on the Ensemble Kalman filter, the assessment is performed with the North Atlantic DRAKKAR configuration of NEMO version 3.4 from January 1, 2005 to June 30, 2006. The horizontal resolution is 1/4°, which is considered as eddy-permitting in the mid-latitudes (Candille et al., 2015). The impact of four observational networks (two JASON and ENVISAT satellites and two in situ ARGO measurements) is evaluated individually and together, on the free run ensemble as well as on the assimilated ensembles. Our results show that the gain of information brought by the satellite data is generally stronger and spatially more homogeneous than with ARGO, but that as compared to the satellites, ARGO brings additional information in the tropical Atlantic. We also show that assimilating two satellites at the same time brings quantitatively twice as much information as assimilating only one satellite, and that assimilating ARGO data in addition to the two altimetric data does not add a lot more information, as assimilating altimetric data already decreases considerably the ensemble spread.
Such evaluation methodologies enable a better understanding of the impact of different observational networks on assimilation systems, and thereby a better and objective design of future multi-mission satellite altimetry constellations.

Candille G., J.-M. Brankart, and P. Brasseur (2015). Assessment of an ensemble system that assimilates Jason-1/Envisat altimeter data in a probabilistic model of the North Atlantic ocean circulation. Ocean Science 11: 425-438.

Le Hénaff M., P. De May, and P. Marsaleix (2009). Assessment of observational networks with the Representer Matrix Spectra method – application to a 3D coastal model of teh Bay of Biscay. Ocean Dynamics 59: 3-20.

 

Poster show times:

RoomStart DateEnd Date
Grand Ballroom Foyer Thu, Oct 22 2015,11:00 Thu, Oct 22 2015,18:00
Pierre Brasseur
CNRS/LGGE
France
Pierre.Brasseur@ujf-grenoble.fr