Sea Ice Concentration (sic)

Several Sea Ice Concentration products are available in pysiral for ingestion in the Level-2 Processor. The code is implemented in pysiral.auxdata.sic.

Global Sea Ice Concentration (SSMIS) - (OSI-401)

The OSI-401 sea ice concentration data product is an operational product available with a timeliness of only 5 hours and thus suitable for near real-time applications.

Changed in version 0.11: The dataset id was renamed from sic:osisaf-operational to sic:osi-401.

Tip

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 sea ice concentration.

Warning

Due to the end of data distribution of SSMIS data in September 2026, it is recommended to use the AMSR2-based sea ice concentration products, such as sic:osi-408 or sic:osi-cdr-amsr2.

Configuration Parameters

The Auxiliary Dataset ID is sic:osi-401 since pysiral version 0.12 and the configuration in the auxiliary data definition of the Level-2 processor definition file is:

- sic:
    name: osi-401
    options:
        exception_on_error: False

Options

To be passed to pysiral.auxdata.sic.OsiSafSIC.

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_concentration: Sea ice concentration in percent
distance_to_ocean: Distance to the nearest ocean grid cell in meters. This variable is defined as the distance to the nearest grid cell with sea_ice_concentration < 15%
distance_to_low_ice_concentration: Similar to distance_to_ocean`, but distance to the nearest grid cell with sea_ice_concentration < 70%.

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_conc_nh_polstere-100_multi_<year><month><day>1200.nc
        ├── ice_conc_sh_polstere-100_multi_<year><month><day>1200.nc
        ├── ...

Global Sea Ice Concentration (AMRS2), (OSI-408)

The OSI-408 sea ice concentration data product is an operational product similar to Global Sea Ice Concentration (SSMIS) - (OSI-401), but based on AMSR2 input data. Datafiles are read with the same python class and handling and extracted variables are similar to the OSI-401 product.

Tip

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 sea ice concentration.

Added in version 0.11: This auxiliary dataset was added in pysiral version 0.11

Configuration Parameters

The Auxiliary Dataset ID is sic:osi-408 since pysiral version 0.12 and the configuration in the auxiliary data definition of the Level-2 processor definition file is:

- sic:
    name: osi-408
    options:
        exception_on_error: False
        fill_pole_hole:
            pole_hole_lat_threshold: 87.0
            pole_hole_fill_value: 100.

The main difference to sic:osi-401 is that the AMSR2 data contains a small pole hole that can be filled with a static value.

Options

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.
fill_pole_hole: Options to fill the pole hole in the AMSR2 data.
- pole_hole_lat_threshold: Latitude threshold in decimal degrees for the pole hole filling (default: 87.0).
- pole_hole_fill_value: Sea ice concentration fill value for the pole hole (default: 100.).

Data Variables

The following variables are returned from this dataset:

sea_ice_concentration: Sea ice concentration in percent
distance_to_ocean: Distance to the nearest ocean grid cell in meters. This variable is defined as the distance to the nearest grid cell with sea_ice_concentration < 15%
distance_to_low_ice_concentration: Similar to distance_to_ocean`, but distance to the nearest grid cell with sea_ice_concentration < 70%.

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_conc_nh_polstere-100_multi_<year><month><day>1200.nc
        ├── ice_conc_sh_polstere-100_multi_<year><month><day>1200.nc
        ├── ...

Global Sea Ice Concentration (i)CDR, (OSI-430/450)

ToDo

To be documented

Global Sea Ice Concentration (i)CDR (AMSR2), (OSI-438/458)

ToDo

To be documented

C3S Sea Ice Concentration (Interim) Climate Data Record (C3S)

The C3S sea ice concentration data product [SIC-C3S-REF] is an (interim) climate data record that provides daily gridded data on sea ice concentration 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.

[SIC-C3S-REF]

Copernicus Climate Change Service (C3S) (2020): Sea ice concentration daily gridded data from 1978 to present derived from satellite observations. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: 10.24381/cds.3cd8b812

Configuration Parameters

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

- sic:
    name: c3s
    options:
        version: v3p0
        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.
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_concentration: Sea ice concentration in percent
distance_to_ocean: Distance to the nearest ocean grid cell in meters. This variable is defined as the distance to the nearest grid cell with sea_ice_concentration < 15%
distance_to_low_ice_concentration: Similar to distance_to_ocean`, but distance to the nearest grid cell with sea_ice_concentration < 70%.

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_conc_<hemisphere>_ease2-250_<cdr|icdr>-<version>_<year><month><day>1200.nc
                ├── ...

There are two options of downloading the datatset:

Climate Data Store: https://cds.climate.copernicus.eu/datasets/sea-ice-concentration
Thredds Server at MET Norway: https://thredds.met.no/thredds/c3s/c3s.html (Select Sea Ice Concentration Climate Data Record (CDR) and Sea Ice Concentration Interim Climate Data Record (iCDR) of the target version).