Problems to remap certain CORDEX, CMIP5/6 datasets provided to C3S

[sol1105]

• clisops version: latest
• Python version:
• Operating System:

Description

There are issues when regridding certain datasets of the data collections

• C3S-CMIP6
• C3S-CMIP5
• C3S-CORDEX

These encompass:

• Some datasets include unmasked missing values in the latitude and longitude coordinate arrays
• Some datasets include erroneous / CF uncompliant metadata (eg. standard_name longitude for the grid_longitudeand longitude variables - cf_xarray uses units, long_name and standard_name to identify lat/lon coordinate variables)
• There is an issue with the detection of degenerated cells in the clisops.core.regrid.Grid class:
  • Not all cells collapsing to lines are detected
  • ESMF additionally considers "smashed" cells as degenerate, which are quadrilateral cells where the opposite bounds are close to each other
• There is an issue with adjusting the longitude frame for datasets with NaNs in the longitude array
• Some datasets have invalid bounds (eg. vertices with dimensionality of 2 instead of 4)

What I did

This is just a log of the problems.
Generally, I tried:

import xarray as xr
import clisops.core as clore

ds=xr.open_dataset("some_dataset")
g=clore.Grid(ds=ds)

• c3s-cmip5/output1/BCC/bcc-csm1-1/rcp85/mon/ocean/Omon/r1i1p1/zos/v20120705
  -> failed because: rlat and lat identified as latitude
• cmip5/output1/BCC/bcc-csm1-1/decadal1991/mon/ocean/Omon/r3i1p1/v20121026
  -> failed because: rlat and lat identified as latitude
• cmip5/output1/LASG-CESS/FGOALS-g2/rcp85/mon/ocean/Omon/r1i1p1/v2/thetao
  -> failed because of time.calendar and time.units ("noleap" "days since 0001-01")
  • for this, the time.units have to be corrected in the metadata (xarraythrows a ValueError upon opening the file), so out of scope
• CMIP6/HighResMIP/BCC/BCC-CSM2-HR/hist-1950/r1i1p1f1/Omon/tos/gn/v20200922
  -> failed because lat and latitude are identified as latitude
• CMIP6/C4MIP/BCC/BCC-CSM2-MR/1pctCO2-rad/r1i1p1f1/Omon/pbo/gn/v20190514
  -> failed because lat and latitude are identified as latitude
• CMIP6/AerChemMIP/BCC/BCC-ESM1/ssp370/r1i1p1f1/Omon/pbo/gn/v20190624
  -> failed because lat and latitude are identified as latitude
• CMIP6/HighResMIP/NCAR/CESM1-CAM5-SE-HR/control-1950/r1i1p1f1/Omon/tos/gn/v20200724
  -> failed because extent ranges from [-1, 359.9] (legal is [-180,360] but max - min may not exceed 360 degree plus grace
  • will have to see if (x)ESMF accepts this with an extent >360 degrees
• CMIP6/CMIP/NCAR/CESM2-FV2/1pctCO2/r1i1p1f1/Omon/intpn2/gn/v20200310
  -> failed because of unmasked missing values in the longitude and latitude arrays (no _FillValue / missing_value attribute)
• CMIP6/OMIP/NOAA-GFDL/GFDL-OM4p5B/omip1/r1i1p1f1/Omon/volcello/gn/v20180701
  -> failed because extent -299.9143 to 1e+20 (unmasked missing values - no _FillValue / missing_value attribute)
• c3s-cordex/output/ARC-44/BCCR/ECMWF-ERAINT/evaluation/r1i1p1/BCCR-WRF331/v1/day/tas/v20200915
  -> failed because vertices have only 2 vertices instead of 4: lat_bnds(rlat, rlon, bnds) with bnds=2