Dynamic Atmospheric Correction (DAC) correction computation

 

 

Because of the aliasing of wind and atmospheric pressure effects in the altimeter measurements (Gaspar and Ponte 1997; Stammer et al. 2000), CTOH coastal sea level anomaly products are provided including a so-called Dynamic Atmospheric Correction (DAC). Within the CTOH processing (Roblou et al, 2011), the DAC is computed as the combination on high-frequency elevations from state-of-the-art Mog2D/T-UGOm 2D model (Carrère and Lyard 2003) simulations plus low-frequency elevations from inverted barometer law (using ECMWF atmospheric pressure products).

In addition, where possible, CTOH computes and removes atmospheric effects from a specific, regional model simulation based on Mog2D/T-UGOm 2D model (1). With respect to the DAC computed from global models, the DAC derived from the regional models make the most of an increased spatial resolution, regional bathymetry solutions and coastlines, and other specific features to provide a better precision in the height prediction over shelves and coastal seas, and are strongly recommended for use.


DAC correction is delivered also in a separate field in case of users want to use another correction.

 

 

References: 

Roblou L., J. Lamouroux, J. Bouffard, F. Lyard, M. Le Hénaff, A. Lombard, P. Marsalaix, P. De Mey and F. Birol (2011) : Post-processing altimiter data towardcoastal apllications and integration into coastal models. Chapter 9 in S. Vignudelli, A.G Kostianoy, P. Cipollini, J. Benveniste (eds.), Coastal Altimetry, Springer Berlin Heidelberg.

Carrère L., Lyard F (2003) : Modeling the barotropic response of the global ocean to atmospheric wind and pressure forcing – comparisons with observations. Geophys Res Lett 30(6):1275.doi:10.1029/2002GL016473

Gaspar P., R.M. Ponte (1997) : Relation between sea level and barometric pressure determined from altimeter data and model simulations. J Geophys Res 102(C1):961–971

Stammer D., C. Wunsch C, R.M. Ponte (2000) : De-aliasing of global high frequency barotropic motions in altimeter observations. Geophys Res Lett 27(8):1175–1178

 

(1) Model simulations are freely available on request on the SIROCCO web site:  http://sirocco.omp.obs-mip.fr/outils/Tugo/Produits/TugoProduits.htm

 

 

 

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