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I've downloaded a netcdf from the Climate Data Store and would like to write a CRS to it, so I can clip it for a shapefile. However, I get an error when assigning a CRS. Below my script and what is being printed. I receive this error after trying to write a crs:

MissingSpatialDimensionError: y dimension (lat) not found. Data variable: lon_bnds

# load netcdf with xarray
dset = xr.open_dataset(netcdf_fn)
print(dset)

# add projection system to nc
dset = dset.rio.write_crs("EPSG:4326", inplace=True)

# mask CMIP6 data with shapefile
dset_shp = dset.rio.clip(shp.geometry.apply(mapping), shp.crs)

dset
Out[44]: 
<xarray.Dataset>
Dimensions:      (time: 1825, bnds: 2, lat: 2, lon: 1)
Coordinates:
  * time         (time) object 2021-01-01 12:00:00 ... 2025-12-31 12:00:00
  * lat          (lat) float64 0.4712 1.414
  * lon          (lon) float64 31.25
    spatial_ref  int32 0
Dimensions without coordinates: bnds
Data variables:
    time_bnds    (time, bnds) object ...
    lat_bnds     (lat, bnds) float64 0.0 0.9424 0.9424 1.885
    lon_bnds     (lon, bnds) float64 ...
    pr           (time, lat, lon) float32 ...
Attributes: (12/48)
    Conventions:            CF-1.7 CMIP-6.2
    activity_id:            ScenarioMIP
    branch_method:          standard
    branch_time_in_child:   60225.0
    branch_time_in_parent:  60225.0
    comment:                none
                    ...
    title:                  CMCC-ESM2 output prepared for CMIP6
    variable_id:            pr
    variant_label:          r1i1p1f1
    license:                CMIP6 model data produced by CMCC is licensed und...
    cmor_version:           3.6.0
    tracking_id:            hdl:21.14100/0c6732f7-2cdd-4296-99a0-7952b7ca911e

1 Answer 1

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You are attempting to clip the whole dataset, but only the pr data var can be clipped. This is because it is the only one with both x and y dimensions. This should work:

dset_shp = dset.pr.rio.clip(shp.geometry, shp.crs)
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  • Thanks, but then I get the following error: NoDataInBounds: No data found in bounds. Data variable: pr.
    – CrossLord
    May 16 at 7:59
  • That means that there was no data when you performed the clip operation.
    – snowman2
    May 16 at 12:07
  • There seems to be data though.. When I print dset.pr this is what I get: array([[[7.368938e-07], ... [1.653116e-07]]], dtype=float32) Coordinates: * time (time) object 2021-01-01 12:00:00 ... 2025-12-31 12:00:00 * lat (lat) float64 0.4712 1.414 * lon (lon) float64 31.25
    – CrossLord
    May 16 at 15:00
  • I thought it might had something to do with the size of the polygon compared to the pixel, since the pixels are much larger than the polygon. However, adding all_touched = True does not help. See: gis.stackexchange.com/questions/390777/…
    – CrossLord
    May 16 at 15:03
  • Might be that the data in the cell is filled with the no data value.
    – snowman2
    May 16 at 20:15

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