Lake Jersey Refinement Example Introduction

Lake Jersey Nesting Refinement Examples

The Lake Jersey is an idealized ROMS example used primarily to test the nesting algorithms for the Refinement Grids Super-Class. It is a wind forced test with strong upwelling and upwelling plumes. The model is started from rest with uniform potential temperature and salinity. It is run only for two days for efficiency with history and time-averaged output every 30 minutes.

Various configurations of refined grids are possible including refinement ratio, telescoping grids (a, d, and e), and nesting layers. The order of the nested grids in ROMS is extremely important so several examples are shown to illustrate the various possibilities. Currently, there are four refined grids inside the coarse grid. The following table summarize the nested grids information:

Lake Jersey Grid Information
Grid	Mesh Size	Refinement Factor	Parent Imin	Parent Imax	Parent Jmin	Parent Jmax	Δx Δy	Grid NetCDF File
a	100x 80x8	-	-	-	-	-	500.0 m	lake_jersey_grd_a.nc
b	66x99x8	1:3 from a	9	31	12	45	166.6 m	lake_jersey_grd_b.nc
c	120x130x8	1:5 from a	34	58	19	45	100.0 m	lake_jersey_grd_c.nc
d	114x60x8	1:3 from a	50	88	50	70	166.6 m	lake_jersey_grd_d.nc
e	132x60x8	1:3 from d	36	80	20	40	55.5 m	lake_jersey_grd_e.nc

Obtaining Test Cases

The test cases can be obtained using Subversion with the following command:

   svn checkout https://www.myroms.org/svn/src/test 

The configuration and input NetCDF file can be found in the test/lake_jersey sub-directory.

Nested Grid Diagram

The following diagram illustrate the location of all the nested grids. Grid a is the coarser grid at 500m resolution. The above table provides the information of the coordinates used to extract the refined grids from the donor grid. The Matlab script grid_extract.m the refine grids. For example:

 >>  Imin = 34;
 >>  Imax = 58;
 >>  Jmin = 19;
 >>  Jmax = 45;
 >>  C = coarse2fine ('lake_jersey_grd_a.nc', 'lake_jersey_grd_c.nc', 5, Imin, Imax, Jmin, Jmax);

In the Menu above, the link Lake Jersey ACDE correspond to a nesting application including grids a, c, d, and e. Notice that this example has two telescoping grids (d and e) and they are ordered last.

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Below is a zoom detailing the relative grid resolutions.

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