Sea Ice Type / Classification (sitype)

Several Sea Ice Type products are available in pysiral for ingestion in the Level-2 Processor.

Global Sea Ice Type (Multi-Sensor) - (OSI-403)

The OSI-403 sea ice type data product is an operational product available with a timeliness of only 5 hours and thus suitable for near real-time applications.

Note

This dataset is not consistently generated for the full time coverage and several versions (-a, -b, -d, -d, …) exist for different time periods. The use of this product should be reserved to near-real-time applications and long-term pysiral generated data records should be based on (interim) climate data records.

Configuration Parameters

The Auxiliary Dataset ID is sitype:osi-403 since pysiral version 0.12 and the configuration in the auxiliary data definition of the Level-2 processor definition file is:

- sitype:
    name: osi-403
    options:
        exception_on_error: False
        fill_valid_sic_gaps: True

Options

  • fill_valid_sic_gaps: Flag to determine whether gap-filling should be used. Setting the value to True ensures that there is valid sea ice type information is available everywhere there is sea ice indicated by the sea ice concentration information. This may be necessary in near coastal regions. The gap filling is based on nearest-neighbour interpolation within a certain range. If this range is exceeded, the sea ice type value will be set to 0.5 (ambiguous).

Note

The dataset id was renamed in pysiral version 0.12 from sitype:osisaf-operational to sitype:osi-403.

Data Variables

The following variables are returned from this dataset:

  • sea_ice_type: Sea ice type as multi-year ice area fraction

  • sea_ice_type_uncertainty: Uncertainty estimate of sea ice type as multi-year ice area fraction

Data Source and Storage

The data access is specified on the OSI-SAF website. The expected grid and data format is the 10km polarstereographic grid in netCDF format. Data files from both hemispheres need to be organized in the following data structure:

<source directory as defined in local_machine_def.yaml>
└── <year>
    └── <month>
        ├── ice_type_nh_polstere-100_multi_<year><month><day>1200.nc
        ├── ice_type_sh_polstere-100_multi_<year><month><day>1200.nc
        ├── ...

C3S Sea Ice Type (Interim) Climate Data Record (C3S)

The C3S sea ice type data product [SITYPE-C3S-REF] is an (interim) climate data record that provides daily gridded data on sea ice type from 1978 to present. It is based on satellite observations and is suitable for climate research and long-term monitoring of sea ice conditions.

The climate data record (CDR) and interim climate data record (iCDR) are technically two separate datasets, but are treated as one in pysiral to allow seamless use of the iCDR after the end of the CDR generation period.

[SITYPE-C3S-REF]

Copernicus Climate Change Service, Climate Data Store, (2020): Sea ice edge and type daily gridded data from 1978 to present derived from satellite observations. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: 10.24381/cds.29c46d83

Note

The availability of this dataset is limited to the northern hemisphere until version 3.0. Southern hemisphere data is added in v4.0.

Configuration Parameters

The Auxiliary Dataset ID is sitype:c3s and the configuration in the auxiliary data definition of the Level-2 processor definition file is:

- sitype:
    name: c3s
    options:
        version: v3p0
        fill_valid_sic_gaps: True
        exception_on_error: False

Options

  • version: The version of the dataset to be used. This should be set to the desired version string, e.g. v3p0.

  • fill_valid_sic_gaps: Flag to determine whether gap-filling should be used. Setting the value to True ensures that there is valid sea ice type information is available everywhere there is sea ice indicated by the sea ice concentration information. This may be necessary in near coastal regions. The gap filling is based on nearest-neighbour interpolation within a certain range. If this range is exceeded, the sea ice type value will be set to 0.5 (ambiguous).

  • exception_on_error: Flag, when set to True, will raise an exception if the auxiliary dataset is not available for the requested time period. If set to False, the processor will continue without the auxiliary dataset and all output is set to NaN. An error will be logged in this case.

Data Variables

The following variables are returned from this dataset:

  • sea_ice_type: Sea ice type as multi-year ice area fraction

  • sea_ice_type_uncertainty: Uncertainty estimate of sea ice type as multi-year ice area fraction

Data Source and Storage

Both CDR and iCDR data files need to be organized in a common directory structure to allow pysiral automatic file lookup depending on the target date.

<source directory as defined in local_machine_def.yaml>
└── <data record type: cdr|icdr>
    └── <version: v{major}p{minor}>      # e.g v3p0
        └── <year>
            └── <month>
                ├── ice_type_<hemisphere>_ease2-250_<cdr|icdr>-<version>_<year><month><day>1200.nc
                ├── ...

There are two options of downloading the datatset:

  1. Climate Data Store: https://cds.climate.copernicus.eu/datasets/satellite-sea-ice-edge-type

  2. Thredds Server at MET Norway: https://thredds.met.no/thredds/c3s/c3s.html (Select Sea Ice Type Climate Data Record (CDR) and Sea Ice Type Interim Climate Data Record (iCDR) of the target version).