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Data

IceNet-MP downloads data using Anemoi. The northern and southern hemispheres are treated as separate datasets.

  • OSI SAF sea ice concentration (serving as both a model input and a forecast target)
  • ERA5 atmospheric reanalysis fields (e.g. temperature, wind, radiation)
  • Argo ocean float observations (e.g. surface and sub-surface ocean state)

Each dataset has a "full" (multi-decadal) and a "sample" (2-3 year) variant, with the resolution and date range encoded into the filename, following Anemoi conventions.

OSI SAF data

To obtain continuous sea-ice concentration records from 1979 through to the present day, a series of OSI SAF datasets with 25 km spatial resolution are combined. Each of these is a L3/L4 reprocessed product, drawing primarily on satellite data.

Period Product Sensor family
1979-01-01 to 2002-12-31 OSI-450-a1 SMMR, SSM/I, SSMIS
2003-01-01 to 2011-10-04 OSI-458 AMSR-E
2011-10-05 to 2012-07-23 OSI-450-a1 SSMIS
2012-07-24 to 2020-12-31 OSI-458 AMSR2
2021-01-01 to 2025-12-31 OSI-438 AMSR2

The full-resolution datasets are detailed in:

  • icenet_mp/config/data/datasets/full_sicnorth_osisaf_25p0km_1979_2025_24h_v1.yaml
  • icenet_mp/config/data/datasets/full_sicsouth_osisaf_25p0km_1979_2025_24h_v1.yaml

and contain the following subset of available variables

  • ice_conc: sea ice concentration
  • status_flag: categorisation of the predominant surface
  • total_standard_uncertainty: uncertainty on the sea ice concentration

Other OSI SAF products

Higher resolution OSI SAF datasets exist (for example with 10 km spatial resolution), but these are not currently used by IceNet-MP.

ERA 5 data

Atmospheric reanalysis data from 1979 through to the present day is retrieved from ERA5 via the CDS MARS API. Data is download at 0.25 degree resolution before being reprojected onto the same 25 km EASE2 grid as the sea-ice concentration records.

The full-resolution datasets are detailed in:

  • icenet_mp/config/data/datasets/full_weathernorth_era5_25p0km_1979_2025_24h_v3.yaml
  • icenet_mp/config/data/datasets/full_weathersouth_era5_25p0km_1979_2025_24h_v3.yaml

and contain the following subset of available variables:

Surface fields (levtype: sfc):

  • 2t: 2 m air temperature
  • sp: surface pressure
  • 10u, 10v: 10 m wind components
  • msl: mean sea level pressure

Pressure-level fields (levtype: pl, at 10, 250, 500 and 1000 hPa):

  • z: geopotential height
  • t: air temperature
  • q: specific humidity
  • u, v: wind components

Time-varying forcings, computed rather than retrieved:

  • cos_julian_day, sin_julian_day: encoded day of year
  • insolation: top-of-atmosphere solar radiation

Argo float data

In-situ ocean observations are drawn from the Argo float programme, gridded onto the same 25 km EASE2 grid as the other datasets. Coverage begins on 1999-07-26, once enough floats were deployed to provide usable spatial coverage, and is sparser in the early years, with many missing dates before continuous daily coverage becomes available.

The full-resolution datasets are detailed in:

  • icenet_mp/config/data/datasets/full_floatnorth_argo_25p0km_1999_2025_24h_v2.yaml
  • icenet_mp/config/data/datasets/full_floatsouth_argo_25p0km_1999_2025_24h_v2.yaml

and contain the following variables:

  • TEMP: ocean temperature
  • PSAL: practical salinity

Missing values (where no float profile is available at a grid cell) are filled with a sentinel value of 99 rather than left as NaN.