Optimized boundary conditions at staircase-shaped coastlines
A 4D-Var data assimilation technique is applied to a rectangular-box configuration of the NEMO in order to analyze the optimal parametrization of boundary conditions at lateral boundaries. The impact of staircase-shaped coastlines is studied by rotating the model grid around the center of the box. Rotations on 30∘ and 45∘ are studied with single and double gyre forcing patterns. It is shown that optimized boundary conditions compensate the errors induced by the staircase-like approximation of the coastline.
KeywordsVariational data assimilation Boundary conditions NEMO model
The author would like to express his gratitude to Julien Le Sommer for helpful discussions on the physical background of the model and to two anonymous reviewers for valuable comments and constructive suggestions on the manuscript.
This work was supported by the French National Programme LEFE/INSU-GMMC. All the contour pictures have been prepared by the Grid Analysis and Display System (GrADS) developed in the Centre for Ocean-Land-Atmosphere Interactions, Department of Meteorology, University of Maryland.
- Barnier B, Madec G, Penduff T, Molines JM, Treguier AM, Sommer JL, Beckmann A, Biastoch A, Boning C, Dengg J, Derval C, Durand E, Gulev S, Remy E, Talandier C, Theetten S, Maltrud M, McClean J, Cuevas BD (2006) Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution. Ocean Dyn 56(5–6):543–567Google Scholar
- Chassignet EP, Marshall DP (2013) Gulf stream separation in numerical ocean models, american geophysical union, pp 39–61. doi: 10.1029/177GM05
- Hascoët L, Pascual V (2004) Tapenade 2.1 user’s guide. Technical Report 0300, INRIA, http://www.inria.fr/rrrt/rt-0300.html
- Madec G, the NEMO team (2012) NEMO ocean engine. Tech. Rep. 27, Note du Pôle de modélisation de l’Institut Pierre Simon LaplaceGoogle Scholar
- Mesinger F, Arakawa A (1976) Numerical methods used in Atmospheric models. GARP Publication Series No 17Google Scholar