FES 2014, a new tidal model on the global ocean with enhanced accuracy in shallow seas and in the Arctic region

Loren Carrere (CLS, France)

CoAuthors

F. Lyard (LEGOS, France); M. Cancet (NOVELTIS, France); A. Guillot (CNES, France)

Event: 2015 Ocean Surface Topography Science Team Meeting

Session: Tides, internal tides and high-frequency processes

Presentation type: Type Oral

Thanks to its current accuracy and maturity, altimetry is considered as a fully operational observing system dedicated to scientific and operational applications. In order to access the targeted ocean signal, altimeter measurements are corrected for several geophysical parameters among which the ocean tide correction is one of the most critical. The accuracy of tidal models has been much improved during the last 20 years. Still, significant errors remain mainly in shelf seas and in polar regions. A new global tidal model, FES 2012, was developed in 2012, taking advantage of longer altimeter time series, improved modelling and data assimilation techniques. Compared to other global tidal models, FES 2012 showed very good performances in all shallow water regions, but the validation diagnostics also pointed out a few regions were the model tended to raise the residual variance; these problems have been partly explained by some local bathymetric issues, such as the Hudson Bay for example.

An improved FES 2014 version was developed in 2014 and finalized in 2015. FES 2014 benefits from recent developments in the physical and numerical modelling (T-UGO model) that result in the decrease by a factor of two of the error of the pure hydrodynamic model.
Several issues detected in the FES2012 bathymetry have been corrected in the FES2014 version. Moreover the grid resolution has been increased in areas of interest like shallow waters and on the slope of the continental shelves.
Additional upgrades have been carried out, such as the use of longer altimeter time series (TP-J1-J2), new altimeter standards (instrumental and geophysical corrections, orbits), and better tide estimations for high latitudes. Finally a larger assimilation dataset has been considered, including tidal gauges.
FES2014 performances have been estimated thanks to comparisons to tidal gauges and altimeter measurements. They show significant improvement particularly in shallow waters and in some part of the Arctic region. Final validation results of FES2014 are presented here.
 

Oral presentation show times:

RoomStart DateEnd Date
Grand Ballroom 2 Wed, Oct 21 2015,11:00 Wed, Oct 21 2015,11:13
Loren Carrere
CLS
France
lcarrere@cls.fr