The ocean engine of NEMO (Nucleus for European Modelling of the Ocean) is a primitive 
equation model adapted to regional and global ocean circulation problems. It is
intended to be a flexible tool for studying the ocean and its interactions with the other
components of the earth climate system over a wide range of global as well as regional 
space and time scales. 

NEMO includes the one- and two-way nesting capability that allows resolution to be focused
over a region of interest by introducing an additional finer resolution grid via the AGRIF 
(Adaptive Grid Refinement in Fortran) software (Madec,G and the NEMO team, 2011).

AGRIF is a package for the integration of adaptive mesh refinement (AMR) features within a 
multidimensional model such as NEMO written in Fortran and discretized on a structured 
grid (Debreu et al., 2008). 
 
The package is designed to create fine regional grids (child grids) in a form that NEMO 
can read in from a coarse NEMO global grid. The idea is to run the fine grid with the 
global grid to provide local increased resolution in the local regions we are focused on.

We will construct a regional model of the South American region using AGRIF in NEMO to 
investigate ocean circulation and biological activity close to the Central and South 
American coasts. 

In the ORCA R2 configuration of the global NEMO model that we plan to use
the grid mesh starts from a 2° ORCA grid mesh and a local transformation is applied within
the Tropics, along with several other selected regions, in order to refine the 
zonal/meridional resolution up to 0.5° at the Equator. 

We plan to increase spacial resolution to ~0.5° using a space refinement
ratio of 4 in an embedded regional model of the Central/South Americas covering a domain 
~125°W to ~25°W, ~35°N to ~60°S. In the current implementation only horizontal refinement 
is available (31 levels in the ORCA R2 configuration). Time refinement ratio will be
set within the model stability.

The grid coordinates and the bathymetry files for the child grid are created off-line 
using the nesting tool in NEMO.

Input forcing data at the sea surface such as the winds and solar heat flux radiation for 
the child grid are also constructed on- or off-line using the nesting tool and the global 
input files for NEMO.  

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Madec, G and the NEMO team, 2011: NEMO ocean engine, version 3.3.
Note du Pˆole de mod´elisation de l’Institut Pierre-Simon Laplace, France, No 27, 332 pp.
ISSN No 1288-1619.

Debreu, L., C. Vouland, and E. Blayo, 2008: AGRIF: Adaptive grid refinement in Fortran.
Computers and Geosciences, 34, 8–13.
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