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User Guide

The xarray backend for EOPF data products "eopf-zarr" has two modes of operation, namely analysis mode (the default) and native mode, which are described in the following.

Analysis Mode

This mode aims at representing the EOPF data products in an analysis-ready and convenient form using the xarray data models DataTree and Dataset. For this reason, it is the default mode of operation when using the "eopf-zarr" backend.

The data products provided in this mode use a unified grid mapping for all their data variables. This means that selected variables are spatially up-scaled or down-scaled as needed, so that the dataset can use a single shared pair of x and y coordinates in the returned datasets.

Function open_dataset()

Synopsis: 

dataset = xr.open_dataset(
    filename_or_obj, 
    engine="eopf-zarr", 
    op_mode="analysis", 
    **kwargs
)

Returns a EOPF data product from Sentinel-1, -2, or -3 in a analysis-ready, convenient form. All bands and quality flags are resampled to a unified, user-provided resolution.

Parameters **kwargs:

  • resolution: Target resolution for all spatial data variables / bands. Must be one of 10, 20, or 60.
  • spline_orders: Spline order to be used for resampling spatial data variables / bands. Must be one of 0 (nearest neighbor), 1 (linear), 2 (bi-linear), or 3 (cubic).
  • spline_orders: Optional spline orders to be used for upsampling spatial data variables / bands. Can be a single spline order for all variables or a dictionary that maps a spline order to applicable variable names or array data types. A spline order is given by one of 0 (nearest neighbor), 1 (linear), 2 (bi-linear), or 3 (cubic). The default is 3, except for product specific overrides. For example, the Sentinel-2 variable scl uses the default 0.
  • agg_methods: Optional aggregation methods to be used for downsampling spatial data variables / bands. Can be a single aggregation method for all variables or a dictionary that maps an aggregation method to applicable variable names or array data types. An aggregation method is one of "center", "count", "first", "last", "max", "mean", "median", "mode", "min", "prod", "std", "sum", or "var". The default is "mean", except for product specific overrides. For example, the Sentinel-2 variable scl uses the default "center".
  • variables: Variables to include in the dataset. Can be a name or regex pattern or iterable of the latter.
  • product_type: Product type name, such as "S2B_MSIL1C". Only required if filename_or_obj is not a path or URL that refers to a product path adhering to EOPF naming conventions.

Function open_datatree()

Synopsis: 

datatree = xr.open_datatree(
    filename_or_obj, 
    engine="eopf-zarr", 
    op_mode="analysis", 
    **kwargs
)

This function is currently not implemented for the analysis mode and will raise a NotImplementedError.

Native Mode

The aim of this mode is to represent EOPF data products without modification using the xarray data models DataTree and Dataset. Content and structure of the original data products are preserved to a maximum extend.

Function open_dataset()

Synopsis: 

dataset = xr.open_dataset(
    filename_or_obj, 
    engine="eopf-zarr", 
    op_mode="native", 
    **kwargs
)

Returns a "flattened" version of the data tree returned by xr.open_datatree() in native mode. Groups are removed by turning their contents into individual datasets and merging them into one. Variables and dimensions are prefixed using their original group paths to make them unique in the returned dataset. For example, the variable b02 found in the group measurements/reflectance/r10m will be renamed to measurements_reflectance_r10m_b02 using the default underscore group separator. The separator character is configurable by setting the group_sep parameter.

The main use case for this function is to allow passing an EOPF data product where the type xr.Dataset is expected (not xr.DataTree) and where the naming of dimensions and variables is not an issue.

Parameters **kwargs:

  • group_sep: Separator string used to concatenate groups names to create prefixes for unique variable and dimension names. Defaults to the underscore character ("_").

Function open_datatree()

Synopsis: 

datatree = xr.open_datatree(
    filename_or_obj, 
    engine="eopf-zarr", 
    op_mode="native", 
    **kwargs
)

Opens a data product as-is including Zarr groups and returns a data tree object.

This function currently returns the result of calling xr.open_datatree(filename_or_obj, engine="zarr", **kwargs).