Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution
|Author(s)||Barnier B1, Madec G2, Penduff T1, Molines J1, Treguier Anne-Marie3, Le Sommer J1, Beckmann A4, Biastoch A5, Boning C5, Dengg J5, Derval C6, Durand E6, Gulev S7, Remy E6, Talandier Claude2, Theetten Sebastien3, Maltrud M8, McClean J9, de Cuevas B10|
|Affiliation(s)||1 : Lab Ecoulements Geophys & Ind, Grenoble, France.
2 : Lab Ocean Dynam & Climatol, Paris, France.
3 : IFREMER, Ctr Brest, Lab Phys Oceans, Plouzane, France.
4 : Univ Helsinki, Dept Phys Sci, Div Geophys, Helsinki, Finland.
5 : Univ Kiel, IfM GEOMAR, Leibniz Inst Meereswissensch, Kiel, Germany.
6 : MERCATOR Ocean, Toulouse, France.
7 : Russian Acad Sci, PP Shirshov Oceanol Inst, Moscow, Russia.
8 : Los Alamos Natl Lab, Fluid Dynam Grp, Los Alamos, NM USA.
9 : UCSD, Scripps Inst Oceanog, La Jolla, CA USA.
10 : Natl Oceanog Ctr, Southampton, Hants, England.
|Source||Ocean Dynamics (1616-7341) (Springer), 2006-12 , Vol. 56 , N. 5-6 , P. 543-567|
|WOS© Times Cited||468|
|Keyword(s)||Eddy/topography interactions, Partial step topography, Momentum advection scheme, Eddy permitting ocean model, Global ocean|
|Abstract||Series of sensitivity tests were performed with a z-coordinate, global eddy-permitting (1/4 degrees) ocean/sea-ice model (the ORCA-R025 model configuration developed for the DRAKKAR project) to carefully evaluate the impact of recent state-of-the-art numerical schemes on model solutions. The combination of an energy-enstrophy conserving (EEN) scheme for momentum advection with a partial step (PS) representation of the bottom topography yields significant improvements in the mean circulation. Well known biases in the representation of western boundary currents, such as in the Atlantic the detachment of the Gulf Stream, the path of the North Atlantic Current, the location of the Confluence, and the strength of the Zapiola Eddy in the south Atlantic, are partly corrected. Similar improvements are found in the Pacific, Indian, and Southern Oceans, and characteristics of the mean flow are generally much closer to observations. Comparisons with other state-of-the-art models show that the ORCA-R025 configuration generally performs better at similar resolution. In addition, the model solution is often comparable to solutions obtained at 1/6 or 1/10 degrees resolution in some aspects concerning mean flow patterns and distribution of eddy kinetic energy. Although the reasons for these improvements are not analyzed in detail in this paper, evidence is shown that the combination of EEN with PS reduces numerical noise near the bottom, which is likely to affect current-topography interactions in a systematic way. We conclude that significant corrections of the mean biases presently seen in general circulation model solutions at eddy-permitting resolution can still be expected from the development of numerical methods, which represent an alternative to increasing resolution.|