Update MPAS to Omega conversion script to include ERA5 based forcing

[vanroekel]

This PR updates the convert_mpaso_ic_to_omega.py to include injection of forcing from ERA5 averaged between 1990-2010. It includes a net surface heat flux and freshwater flux and surface wind stresses. The ERA5 climatology has been uploaded to the Polaris input repository polaris/ocean/realistic_global/forcing along with the SCRIP file needed to remap to an MPASO input grid. This has been tested in an EC30to60 configuration with Omega.

Checklist

• Developer's Guide has been updated
• Documentation has been built locally and changes look as expected
• Testing comment in the PR documents testing used to verify the changes
• New tests have been added to a test suite

[vanroekel]

@xylar and @cbegeman - I wasn't sure what level of testing to do for this PR. I used it to generate a new EC30to60 condition and it compared exactly with my previous file. I also ran it in an omega config and it worked well. I'm happy to test further.

[xylar]

@vanroekel, is this what we should also include in initial conditions produced directly in Polaris? I had been using January wind forcing of year 1958 from JRA because that's the starting point of a G-case, but an ERA5 climatology is fine, too.

[xylar]

@vanroekel, are you wanting to create new cached initial conditions with this forcing as the default for use in Polaris for cached initial conditions going forward?

[xylar]

@vanroekel, it looks like you need to rebase to fix a conflict.

[vanroekel]

I was mostly working on something more realistic than the simple windstress in the global test case conversion script. I needed something that included buoyancy fluxes. So I'm mostly thinking of this as more of a test for KPP that is more realistic. I could make a polaris task that uses this, but I mostly wanted to document what I did for testing of the KPP PR.

Is the JRA use for spinup to new initial conditions for E3SM? I hadn't thought of using this for E3SM spinups. I could switch to JRA, but there is also a ERA5 based G-case in development that will replace JRA.

I'll rebase now.

[xylar]

@vanroekel, all good, I just wanted to see if I needed to make changes on my side. It sounds like not yet (if at all).

[xylar]

@vanroekel, this looks fine to me. Since this is only an interim solution in any case, I feel like the standards of elegance and reproducability aren't as high as they will be for workflows later in our development cycle.

[cbegeman]

@xylar and @cbegeman - I wasn't sure what level of testing to do for this PR. I used it to generate a new EC30to60 condition and it compared exactly with my previous file. I also ran it in an omega config and it worked well. I'm happy to test further.

It sounds like you've done enough testing to show that you can use the script to generate the expected result. Since this is mostly for provenance purposes, I don't think we need to do any additional testing.

[cbegeman]

Approving on the basis of visual inspection and @vanroekel 's testing