Impact of the assimilation of high-frequency data in a regional model with high resolution

Mounir Benkiran (mercator-ocean, France)

CoAuthors

Elisabeth Remy (Mercator-ocean, France); Guillaume Reffray (Mercator-Ocean, France)

Event: 2017 Ocean Surface Topography Science Team Meeting

Session: Science III: Mesoscale and sub-mesoscale oceanography

Presentation type: Type Poster

Impact of the assimilation of high-frequency data in a regional model with high resolution

Mounir Benkiran, Elisabeth Rémy and Guillaume Reffray

MERCATOR Ocean 8-10 Rue Hermes 31526 Ramonville St Agne Cedex

Abstract


Mercator-Ocean has developed a regional forecasting system at 1/36° (~3km) resolution over the North East Atlantic (IBI: Iberia, Biscay and Irish), taking advantage of the recent developments in NEMO. The model was forced by ERA-interim products (every 3 hours) including the atmospheric pressure. In addition to atmospheric forcing, the model includes astronomical tidal forcing. This regional forecasting system uses boundary conditions from the Mercator-Ocean regional system (with data assimilation, 1/12° resolution, PSY4). The assimilation component of the Mercator Ocean system, is based on a reduced-order Kalman filter (the SEEK or Singular Extended Evolutive Kalman filter). An IAU method (Incremental Analysis Updates) is used to apply the increments in the system. A 3D-Var scheme corrects for the slowly evolving large-scale biases in temperature and salinity. The data assimilation system allows to constrain the model in a multivariate way with Sea Surface Temperature (AVHRR + Multi-satellite High resolution), together with all available satellite Sea Level Anomalies, and with in situ observations from the CORA-04 data base, including ARGO floats temperature and salinity measurements. The background SLA field accounts for the high frequency signal determined by the model and the forcing by atmospheric pressure.
In this study we show the impact of the assimilation of altimetry data unfiltered and uncorrected from fast atmospheric frequencies. Altimetry data assimilated contain the effect of atmospheric pressure and wind unlike conventional data used in operational systems.


 

Poster show times:

RoomStart DateEnd Date
Concerto Ballroom Thu, Oct 26 2017,14:00 Thu, Oct 26 2017,18:00
Mounir Benkiran
mercator-ocean
France
mbenkiran@mercator-ocean.fr