EUMETSAT Ocean and Sea Ice SAF (OSI SAF), produced by the Norwegian Meteorological Institute
EUMETSAT OSI SAF Sea-Ice Index v3.0 (OSI-420-a)
Sea ice extent (area with concentration above 15%) and sea ice area in km2, daily and monthly, for the Northern and Southern Hemispheres (plus global and about 25 regional seas in the same archive), from October 1978 with one day of latency. Derived from the OSI SAF sea ice concentration climate data records OSI-450-a1, OSI-430-a and OSI-438 (doi:10.15770/EUM_SAF_OSI_0023, 10.15770/EUM_SAF_OSI_2014, 10.15770/EUM_SAF_OSI_0024). Text files: '#' header lines, then decimal year, year, month, day and extent (km2), with a source code column in the daily files only; -999 marks missing values. Uses a different algorithm from NSIDC's Sea Ice Index, so its values differ (September 2026 Arctic mean: 5.34 million km2 here, 4.81 in NSIDC's); the two are never mixed in one series.
Numbers published from it
Licence and credit
- Licence
- CC BY 4.0
- What the terms say
“The EUMETSAT OSI SAF products are made available without charge under a CC-BY-4.0 licence. You may share (copy and redistribute the material in any medium or format for any purpose, even commercially) and adapt (remix, transform, and build upon the material for any purpose, even commercially). You must provide attribution and cannot apply additional restrictions.”
From the producer's terms, checked 2026-10-04; re-checked automatically every week.
- Credit we give
- EUMETSAT OSI SAF, Sea-Ice Index v3.0 (2026), OSI-420-a, doi:10.15770/EUM_SAF_OSI_0026, produced by the Norwegian Meteorological Institute. CC BY 4.0.
- Copy of the raw file
- Allowed: we keep a public copy of every version we use.
- Cite as
- EUMETSAT OSI SAF, Sea-Ice Index (2026), OSI-420-a, doi:10.15770/EUM_SAF_OSI_0026
Files
Northern Hemisphere monthly mean sea ice extent (km2), one row per month dated the 16th, from January 1978 (-999 until October 1978). Five fields per row.
https://osisaf-hl.met.no/archive/osisaf/sea-ice-index/v3p0/timeseries/nh/ice_extent_nh_sii-v3p0_monthly.txtNorthern Hemisphere daily sea ice extent (km2) from October 1978, with the input record's code per row.
https://osisaf-hl.met.no/archive/osisaf/sea-ice-index/v3p0/timeseries/nh/ice_extent_nh_sii-v3p0_daily.txtSouthern Hemisphere monthly mean sea ice extent (km2), same layout as the northern file.
https://osisaf-hl.met.no/archive/osisaf/sea-ice-index/v3p0/timeseries/sh/ice_extent_sh_sii-v3p0_monthly.txtSouthern Hemisphere daily sea ice extent (km2) from October 1978, with the input record's code per row.
https://osisaf-hl.met.no/archive/osisaf/sea-ice-index/v3p0/timeseries/sh/ice_extent_sh_sii-v3p0_daily.txt
Status
- Programme
- Version 3.0 has been operational since 4 May 2026 (authorised 30 April 2026); the files are regenerated daily (monthly northern file created 4 October 2026). European (EUMETSAT, Norwegian Meteorological Institute), so not exposed to US budget cuts.
- Updates
- Daily (one day of latency; monthly values after each month ends)
- Last check
- Fetched (2026-10-05T11:04:30Z)
- Independent sources measuring the same thing
- Sea Ice Index, Version 4 (G02135)