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

Mounir Benkiran (CLS, France)

CoAuthors

Claire Dufau (CLS, France); Jean-Michel Lellouche (Mercator Ocean, France); Yann Drillet (Mercator Ocean, France)

Event: 2014 Ocean Surface Topography Science Team Meeting

Session: Quantifying Errors and Uncertainties in Altimetry data

Presentation type: Type Oral

Mercator-Ocean has developed a regional forecasting system at 1/12° 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 global reanalysis (GLORYS: GLobal Ocean ReanalYses and Simulations).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. The error statistics are represented in a sub-space spanned by a small number of dominant 3D error directions. 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-03 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 uncorrected fast atmospheric frequencies. Altimetry data assimilated contain the effect of atmospheric pressure and wind unlike conventional data used in operational systems.
 

Oral presentation show times:

RoomStart DateEnd Date
Ballroom Thu, Oct 30 2014,10:15 Thu, Oct 30 2014,10:30
Mounir Benkiran
CLS
France
mbenkiran@cls.fr