Start › Sea Ice Concentration › AMSR-E/AMSR2 › Time Series Important Notice
We have found a data processing problem that has caused a negative offset in our Arctic sea-ice extent data since 2018, giving the incorrect impression that we had already reached the historic minimum from 2012.The data have now been reprocessed and the plots should now be correct. The minimum sea ice extent in 2020 was reached in mid-September and is was the second-lowest minimum (lowest on record was in 2012).
 Click on the image to enlarge. Arctic sea ice extent (total area of at least 15% ice concentration) since 1972. |
 Click on the image to enlarge. Antarctic sea ice extent (total area of at least 15% ice concentration) since 1972. |
 Click on the image to enlarge. Annual Arctic sea ice extent (total area of at least 15% ice concentration) for selected years since 1979. |
 Click on the image to enlarge. Annual Antarctic sea ice extent (total area of at least 15% ice concentration) for selected years since 1979. |
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 Click on the image to enlarge. Annual Arctic sea ice extent (total area of at least 15% ice concentration) for the last 6 years and the minimum year 2012. |
 Click on the image to enlarge. Annual Antarctic sea ice extent (total area of at least 15% ice concentration) for the last 7 years. |
Time Series Of Sea Ice Extent
To adapt data from a newer source to the data from an older source, the newer data were linearly transformed such that both mean and standard deviation or the newer time series matched the mean and standard deviation of the older time series in the overlap period.
In addition, the data are smoothed by a 5-day running mean. Consequently, the current day and the day before are only averaged over three respectively four days and might still vary slightly for two (resp. one) days
Since July 3, 2012, AMSR2 data is displayed which is adapted with the same parameters as its predecessor AMSR-E. The fit parameters are not deduced by comparing it during an overlap period to another time series. Hence, the data ought to be treated with caution until confirmation by independent sources.
| # | Period | Algorithm | Sensor, Frequencies, Source | Adapted to | Overlap period |
|---|---|---|---|---|---|
| 1. | 1972 - 2002 | NASA Team | SMMR & SSM/I, 19 and 37 GHz from NSIDC(1) | #2. | 1989 - 2002 |
| 2. | Oct 26, 1978 - Dec 2010 | NASA Team | Sea ice concentrations from NIMBUS-7 SMMR and DMSP SSM/I-SSMIS passive microwave data, 19 and 37 GHz, from NSIDC(2) | reference only, but not part of the time series because of some gaps 1978 - 1988 | |
| 3. | 2003 - Oct 4, 2011 | ASI | AMSR-E, 89 GHz | #2. | 2002 - 2007 |
| 4. | Oct 5, 2011 -Jul 2, 2012 | ASI | SSMIS F-17, 91 GHz | #3. | Sep 2010 – Sep 2011 (using SSMIS F-17 data) |
| 5. | Jul 3, 2012 to date | ASI | AMSR2, 89 GHz | #3. (same fit parameters used) | Jul 3, 2012 to date |
Time Series Data
Text files containing the total sea ice extent in the northern hemisphere until end of 2019 can be found here (extent_n_19720101-20191231_amsr2.txt) and for the southern hemisphere here (extent_s_19730101-20191231_amsr2.txt). The daily data of the current year 2020 are available here (extent_n_2020_amsr2_smooth.txt) for the North and here (extent_s_2020_amsr2_smooth.txt) for the South.
More data can be found in the Data Archive. To quickly browse datasets, please have a look at the Data Browser.
How to cite
Please help maintaining this service by properly citing and acknowledging if you use the data for publications:
Spreen, G., L. Kaleschke, and G.Heygster (2008), Sea ice remote sensing using AMSR-E 89 GHz channels J. Geophys. Res.,vol. 113, C02S03, doi:10.1029/2005JC003384.
Contact
For questions regarding the data please contact Gunnar Spreen, Christian Melsheimer, or Georg Heygster.
For questions related to the website and data-browser please contact Malte Gerken.
Institute of Environmental Physics, University of Bremen, Germany.