C3S_34e Meeting with Ouranos and CRIM: 30th June 2021

[agstephens]

Proposed agenda - C3S_34e Meeting with Ouranos and CRIM: 30th June 2021

1. Minutes and actions from previous meeting

Previous minutes: #100

Previous actions

• AS: Put regridding higher up the agenda next month
• AS: move meetings back to 4-weekly from today - and edit meeting settings in Zoom
• ES: Create an issue on the xarray repository to explain the _FillValue in 1D coordinate variables, and that we believe these contravene the CF-Conventions (See "coordinate variable" section under: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#terminology). See: _FillValue added with output to netcdf pydata/xarray#5448
• MS: Raise an xESMF issue to discuss haloes

2. Grids and regridding [Martin]

• some dedicated time to focus on regridding issues

3. Project update: c3s_34e [Ag]

• recent developments:
  • C3S have slightly modified their priorities:
    • subset by list of values (level and time)
    • temporal averages (monthly or annual)
    • CORDEX subsetting
  • still working on dynamic fixes in daops to modify Decadal CMIP6 runs
  • working on dashboard endpoint

4. Project updates: relevant Ouranos/CRIM projects [David/Tom]

Ouranos:

CRIM:

5. Discussion:

• STAC discussions/work
• OGC

6. Agree next steps and next meeting

[ellesmith88]

@agstephens The fill value issue is this one: pydata/xarray#5448, it was closed as a duplicate.

[sol1105]

The slides regarding regridding: Link

Regarding CMIP6 station data requested by CFMIP:
http://clipc-services.ceda.ac.uk/dreq/u/dim:site.html
Would be 2D datasets (time, site/station)
Example: ESGF http download link

[agstephens]

Minutes - C3S_34e Meeting with Ouranos and CRIM: 30th June 2021

1. Minutes and actions from previous meeting

Previous minutes: #100

Previous actions

• AS: Put regridding higher up the agenda next month
• AS: move meetings back to 4-weekly from today - and edit meeting settings in Zoom
• ES/AS: Run the cf-checker on example files generated by Xarray to see if 1D coordinate variables with _FillValue set will fail cf-checks. Do we need to take action?
• ES: Create an issue on the xarray repository to explain the _FillValue in 1D coordinate variables, and that we believe these contravene the CF-Conventions (See "coordinate variable" section under: https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#terminology). See: _FillValue added with output to netcdf pydata/xarray#5448
• MS: Raise an xESMF issue to discuss haloes - ongoing

2. Grids and regridding [Martin]

MS presented on:

• Out-of-source domain / unmapped grid cells
• Masking - renormalising / adaptive-masking
• Grid halos / ghost cells
• See presentation: https://docs.google.com/presentation/d/1nAX5gpcjAyi8Dkqbmb7U-KGuUn2IQhB7IEJd3RoKNHw/edit#slide=id.p

3. Project update: c3s_34e [Ag]

• recent developments:
  • C3S have slightly modified their priorities:
    • subset by list of values (level and time)
    • temporal averages (monthly or annual)
    • CORDEX subsetting
  • still working on dynamic fixes in daops to modify Decadal CMIP6 runs
  • working on dashboard endpoint

4. Project updates: relevant Ouranos/CRIM projects [David/Tom]

Ouranos (TL):

• working on intake catalog of NcML datasets (to simplify user view)
• working on reading WFS daily station data into xclim/xarray

5. Discussion:

• clisops temporal averaging:
  • Temporal averaging - note that xarray can resample - but might not create the correct CF metadata. This has been discussed in relation to cf-xarray.
• STAC discussions with CMIP6 Object Store
  • DH: Ouranos will be involved in a proposal to set up CMIP6 object store later this year
  • AS: We are engaging with PANGEO people regarding how this is done in Zarr, we have some experience. Also, we have people working on a STAC solution that will work for ESM (and other) data.

6. Agree next steps and next meeting

Next meeting date: Thursday 29th July.