# Modifiying the land sea mask **URL:** \ **Category:** OpenIFS\ **Tags:** openifs-configuration-and-namelists, openifs-40r1, openifs-surface-boundary\ **Created:** [26 April 2019 10:10 UTC](https://forum.ecmwf.int/t/modifiying-the-land-sea-mask/12121 "2019-04-26T10:10:01Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Jan\_Streffing](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/j/d26b3c/32.png) [@Jan\_Streffing](https://forum.ecmwf.int/u/Jan_Streffing)\ **Post date:** [26 April 2019 10:10 UTC](https://forum.ecmwf.int/t/modifiying-the-land-sea-mask/12121/1 "2019-04-26T10:10:01Z")
I would like to run an OpenIFS setup (T159) coupled to a low resolution ocean. The ocean model and OpenIFS do not fully agree as to which surface points should be wet points: ![FESOM2 Core2 mesh](https://forum.ecmwf.int/uploads/default/original/2X/d/de64135f47056232d1a740416475dedd4a764572.jpeg "FESOM2 Core2 mesh") ![lsm before](https://forum.ecmwf.int/uploads/default/original/2X/b/bd55741f8864ecdfa5232776d0286ad44dda7c02.png "lsm before") I used Joakims skript for generating oasis mask files to remove the OpenIFS sea points over what the ocean considers as land. The changes are written into the both masks.nc file for Oasis and the lsmoro file for OpenIFS input. ![lsm after](https://forum.ecmwf.int/uploads/default/original/2X/1/151c723f845c99cfccf75ce11bd4939d5e6e4aef.png "lsm after") I also did the same for the EC-Earth runoff mapper file where I had merge some runoff basins and invent new discharge points. I re-generated the Oasis remapping weight files with the new mask and tried to start the coupled model with the new lsmoro only to crash right after initialization. Turns out the lsmoro part of the changes was apparently not effective. OpenIFS still tries to get SST (and SIC) from the Ocean model at the points that are now no longer ocean as in the Oasis mask. The result is that the areas I have now designated as dry points have a surface temperature of 0 K, leading to the crash. ![SKT first timestep](https://forum.ecmwf.int/uploads/default/original/2X/f/f1f9227895337fc88692a77931c51b5859a8a651.png "SKT first timestep") I double-checked the lsmoro files before and after my modifications and I can not see the problem there. I would say the modifications seem to have worked. I would have expected OpenIFS to calculate land surface temperatures for these points now. ![lsmoro before](https://forum.ecmwf.int/uploads/default/original/2X/8/88db9c78efc089545ecaae44de0b47a370820520.png "lsmoro before") ![lsmoro after](https://forum.ecmwf.int/uploads/default/original/2X/5/59aa0e2a18f7483289cec6e7594be22a48d8c19f.png "lsmoro after") ![lsmoro diff](https://forum.ecmwf.int/uploads/default/original/2X/f/f11a19ec02ed4eed657a7e270574a3c350a14932.png "lsmoro diff") That leads me to the question if there is any other place / file where I have to change the land sea mask for OpenIFS to start considering these points as land and not expect values from the coupler? Cheers, Jan ---
**Author:** ![Jan\_Streffing](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/j/d26b3c/32.png) [@Jan\_Streffing](https://forum.ecmwf.int/u/Jan_Streffing)\ **Post date:** [6 May 2019 19:57 UTC](https://forum.ecmwf.int/t/modifiying-the-land-sea-mask/12121/2 "2019-05-06T19:57:26Z")
Overdue update: There is a second land sea mask in the ICMGG\*\*\*\*INIT file and apparently that's the one that is used here. ---
**Author:** ![Glenn\_Carver](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/g/e495f1/32.png) [@Glenn\_Carver](https://forum.ecmwf.int/u/Glenn_Carver)\ **Post date:** [23 July 2019 12:05 UTC](https://forum.ecmwf.int/t/modifiying-the-land-sea-mask/12121/3 "2019-07-23T12:05:52Z")
Hi Jan, Sorry to have missed replying to this one. Yes, I don't know why there are two land-sea masks in the model input files but I'm glad you found the right one and solved the problem. Cheers,  Glenn