diaptr land suppression eORCA12

[mathiot]

Context

Diaptr with land suppression is not working well. Whatever the variables and the bassins, data are missing in some place because there is no processor at these locations (Antarctica and at the latitude of Bering strait) (see attachment).

Analysis

The line use to plot diaptr is defined in iom_init.F90:

CALL dom_ngb( 180., 90., ix, iy, 'T' ) !  i-line that passes near the North Pole : Reference latitude (used in plots)

In my eORCA12 decomposition, some processors are missing along this line (land processor).

It could affect any configuration using land suppression (more likely at high resolution) in NEMO_3.6_STABLE and in the trunk.

Fix

I suggest to move the test on point (180E,90N) to (-168.7E,65.6N). The suggested point, is a point in Bering Strait. The only land points cross along this line are the points over Antarctica. The issue with this is that the latitude vector range will be [-86.5:~80N (not 90N)] instead of [-86.6N:90N]. However, the latitude vector is not correct anyway in the Arctic (because or the grid distortion). So I think the latitude coordinate issue is minor.

[rbourdal]

swich reference point (and line) as suggested by P. Mathiot.
New reference line passes through Bering Strait (black line on the plot)