Global Snow and Ice - September 2013
Beginning in November 2017, NCEI will use version 3 of the National Snow and Ice Data Center's (NSIDC) monthly sea ice extent index. All historical monthly sea ice extent values will be updated to version 3, but historical reports will not be updated. For additional information on the methodology changes and comparisons to version 2, please visit the National Snow and Ice Data Center.
Sea Ice Extent
|September 2013||Sea Ice Extent||
(out of 35 years)
|million km2||million mi2||Year(s)||million km2||million mi2|
Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2013 (35 years)
According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for September 2013 was 5.35 million square km (2.07 million square miles), 17.94 percent below the 1981-2010 average, and the sixth smallest September Arctic sea ice extent on record. The sea ice extent during September was 1.72 million square km (664,000 square miles) larger than the record low September sea ice extent which occurred in 2012. Despite the below average sea ice extent, this was the largest September Arctic sea ice extent since 2009. Most regions of the Arctic experienced below-average sea ice during the month, with the exception of the East Siberian Sea, which had near-average ice coverage. September Arctic sea ice extent is decreasing at an average rate of 13.7 percent per decade.
On September 13th, the Arctic sea ice extent reached its annual minimum, marking the end of the summer melt season and the beginning of the winter growth season. The annual minimum extent was 5.10 million square km (1.97 million square miles), marking the sixth smallest annual minimum extent on record. The 2013 minimum was 1.69 million square km (653,000 square miles) larger than the record minimum extent that occurred on September 16th, 2012 and about 1.12 million square km (432,000 square miles) smaller than the 1981-2010 average.
The September 2013 Southern Hemisphere sea ice extent was 19.77 million square km (7.63 million square miles), 5.22 percent above the 1981-2010 average. This marked the largest September Antarctic sea ice extent on record, surpassing the previous record large September extent of 19.43 million square km (7.50 million square miles) that occurred in 2012. September Southern Hemisphere sea ice extent is increasing at an average rate of 1.1 percent per decade.
On September 22nd, the Antarctic sea ice extent reached its annual maximum, marking the end of the winter growth season and the beginning of the summer melt season. The annual maximum extent was 19.47 million square km (7.52 million square miles), marking the largest annual maximum extent on record. The 2013 maximum was about 30,000 square km (11,600 square miles) larger than the previous record large Antarctic annual maximum sea ice extent, which occurred in 2012, and 2.6 percent higher than the 1981-2010 average.
When combining the Northern Hemisphere and Southern Hemisphere sea ice extents, the globally-averaged sea ice extent during September was 25.12 million square km (9.70 million square miles). This was 0.71 percent below the 1981-2010 average and the 13th smallest global September sea ice extent since records began in 1979 and the largest September global sea ice extent since 2006.
For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.