10/09 - 2nd-Lowest Arctic Ice Extent For The Month In 30 Yrs. - Ice Still N. Of Svalbard, F.J. Land

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November 3, 2009
Warm winds slow autumn ice growth


Sea ice extent grew throughout October, as the temperature dropped and darkness returned to the Arctic. However, a period of relatively slow ice growth early in the month kept the average ice extent low—October 2009 had the second-lowest ice extent for the month over the 1979 to 2009 period.

Overview of conditions

Sea ice extent averaged over October 2009 was 7.50 million square kilometers (2.90 million square miles). This was 1.79 million square kilometers (691,000 square miles) below the 1979 to 2000 mean for October, but 730,000 square kilometers (282,000 square miles) above the record low for the month, which occurred in October 2007.


Figure 1. Arctic sea ice extent for October 2009 was 7.50 million square kilometers (2.90 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data.

Conditions in context

In the fall, cold conditions and polar darkness return to the Arctic. As is typical for this time of year, ice growth was brisk in October, growing at an average 96,000 square kilometers per day (37,000 square miles per day).

However, the growth rate slowed for a time in early October, coinciding with strong winds from the south over central Siberia. The winds helped prevent ice from forming along the Siberian coast. At the end of the month, extensive areas of open water regions were still present in the northernmost North Atlantic, and north of Alaska. The ice edge was north of both Svalbard and Franz Josef Land.


November 1, 2009. The solid light blue line indicates 2009; dark blue shows 2008, dashed green indicates 2007; light green shows 2005; and solid gray indicates average extent from 1979 to 2000. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

October 2009 compared to past years

The period of slow ice growth at the beginning of the month helped to keep October average ice extent low. Arctic sea ice extent was 950,000 square kilometers (367,000 square miles) below October 2005 and 890,000 square kilometers (340,000 square miles) below that measured in 2008. Although ice extent for October 2009 was 730,000 square kilometers (282,000 square miles) above the record low for the month in 2007, it steepened the linear trend for October slightly to -5.9 % per decade.


Figure 3. Monthly October ice extent for 1979 to 2009 shows a decline of 5.9% per decade.

EDIT

http://nsidc.org/arcticseaicenews/index.html