Zarr plugin

[martindurant]

Example

In [1]: %cat cat.yaml
sources:
  newman:
    description: Newmann Ensemble
    driver: zarr
    args:
      urlpath: "gcs://pangeo-data/newman-met-ensemble/"

In [2]: import intake

In [3]: cat = intake.Catalog('cat.yaml')

In [4]: cat.newman.read_chunked()
Out[4]:
<xarray.Dataset>
Dimensions:    (ensemble: 9, lat: 224, lon: 464, time: 12054)
Coordinates:
  * lat        (lat) float64 25.06 25.19 25.31 25.44 25.56 25.69 25.81 25.94 ...
  * lon        (lon) float64 -124.9 -124.8 -124.7 -124.6 -124.4 -124.3 ...
  * time       (time) datetime64[ns] 1980-01-01 1980-01-02 1980-01-03 ...
Dimensions without coordinates: ensemble
Data variables:
    elevation  (ensemble, lat, lon) float64 dask.array<shape=(9, 224, 464), chunksize=(1, 224, 464)>
    mask       (ensemble, lat, lon) int32 dask.array<shape=(9, 224, 464), chunksize=(1, 224, 464)>
    pcp        (ensemble, time, lat, lon) float64 dask.array<shape=(9, 12054, 224, 464), chunksize=(1, 287, 224, 464)>
    t_max      (ensemble, time, lat, lon) float64 dask.array<shape=(9, 12054, 224, 464), chunksize=(1, 287, 224, 464)>
    t_mean     (ensemble, time, lat, lon) float64 dask.array<shape=(9, 12054, 224, 464), chunksize=(1, 287, 224, 464)>
    t_min      (ensemble, time, lat, lon) float64 dask.array<shape=(9, 12054, 224, 464), chunksize=(1, 287, 224, 464)>
    t_range    (ensemble, time, lat, lon) float64 dask.array<shape=(9, 12054, 224, 464), chunksize=(1, 287, 224, 464)>
Attributes:
    _ARRAY_DIMENSIONS:         {'ensemble': 9, 'lat': 224, 'lon': 464, 'time'...
    history:                   Version 1.0 of ensemble dataset, created Decem...
    institution:               National Center for Atmospheric Research (NCAR...
    nco_openmp_thread_number:  1
    references:                Newman et al. 2015: Gridded Ensemble Precipita...
    source:                    Generated using version 1.0 of CONUS ensemble ...
    title:                     CONUS daily 12-km gridded ensemble precipitati...

[martindurant]

(branched from #6 , commit log will look more reasonable after that is merged)

[mmccarty]

Tested locally and it works so far! Had to install a few dependencies.

conda install gcsfs zarr -c conda-forge