diff --git a/docs/earthdata-varinfo.ipynb b/docs/earthdata-varinfo.ipynb index 1fdaa36..742f879 100644 --- a/docs/earthdata-varinfo.ipynb +++ b/docs/earthdata-varinfo.ipynb @@ -198,6 +198,17 @@ "source": [ "In the output above, `/Grid/precipiationCal` has three dimensions: `/Grid/time`, `/Grid/lat` and `/Grid/lon`. These dimension variables also refer to their respective [bounds variables](http://cfconventions.org/Data/cf-conventions/cf-conventions-1.10/cf-conventions.html#cell-boundaries). Because `get_required_variables` is recursive, the bounds attributes are also considered required variables for `/Grid/precipitationCal`.\n", "\n", + "When a `VarInfoFromDmr` or `VarInfoFromNetCDF4` object is instantiated, specific CF Convention metadata attributes of each variable are checked for references to other variables. These references are then fully qualified to absolute paths for later use by methods such as `VarInfoFromNetCDF4.get_required_variables`. The metadata attributes expected to contain references to other variables, per the CF Conventions, include:\n", + "\n", + "* [ancillary_variables](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#ancillary-data)\n", + "* [coordinates](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#coordinate-types), see also [here](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#coordinate-system).\n", + "* [grid_mapping](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#grid-mappings-and-projections)\n", + "* [bounds](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#cell-boundaries)\n", + "* [cell_measures](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#cell-measures)\n", + "* [geometry, interior_ring, node_coordinates, node_count, nodes and part_node_count](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#geometries)\n", + "\n", + "It is possible that metadata attributes may be absent from a variable or contain incorrect metadata. In these cases, these attributes can be added or overriden using a configuration file specified by the `config_file` kwarg during instantiation of either a `VarInfoFromNetCDF4` or `VarInfoFromDmr` object.\n", + "\n", "### More variable relationship examples:\n", "\n", "Users can supply a set of variable full paths to the following functions to retrieve only the spatial or temporal dimensions for a given variable (methods below are present on both the `VarInfoFromNetCDF4` and `VarInfoFromDMR` classes:\n",