interpolation method

[wwieder]

Hey, sorry to ping you out of the blue with this comment, but Rosie shared your repo. The work here looks good! Very encouraging.

I wanted to ask about the interpolation method being used? I'll note that I'm not an expert on such matters, but the CLM diagnostics package uses area-conservative regridding to go from the ne30 to f09 grids, whereas it looks like currently this is set up to do bilinear interpolation. Not sure what's right, but I wanted to start a discussion.

xesmf_clm_fates_diagnostic/src/xesmf_clm_fates_diagnostic/regrid_and_plot_w_timeseries.py

Line 65 in f7c3e69

regridder_obsdata = xe.Regridder(ds, ds_out_gpp, 'bilinear', periodic=True)

[maritsandstad]

Thanks for commenting. Yes, it uses bilinear for the moment. There was no deep thought that went into that, but sometimes the requirements for area conserving are a bit stricter, so first order this was going to just work quickly and easily so plots can be reviewed. Happy to test out area conserving as well, I agree that it's probably more correct, but I find (being no expert in anything) that often for things like this, where absolute precision might not be the primary goal, bilinear is good enough.

[maritsandstad]

@wwieder I've now updated to use conservative_normed which seemed to me the most appropriate alternative, to retain the area conservation, but avoid coastal artefacts which can be a problem with conservative regridding, particularly for land only data. Testing with this seems alright to me, but I don't really have great intuition on what the data should look like, so I can't guarantee, anyways it's really easy to change, and it can even be made a dynamical option, but I doubt that would be worth it for most use cases...