September Sea Ice Outlook: July Report

Release Date: 
13 July 2011

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Thank you to all contributors of the July Sea Ice Outlook. We received 16 responses for the Pan-Arctic report (Figure 1), with estimates in the range of 4.0 to 5.5 million square kilometers for the September arctic mean sea ice extent. The median value was 4.6 million square kilometers; the quartile values were 4.3 and 4.7 million square kilometers, a rather narrow range given the intrinsic uncertainty of the estimates on the order of 0.5 million square kilometers. It is important to note for context that all 2011 estimates are well below the 1979–2007 September climatological mean of 6.7 million square kilometers.

There continues to be a consensus for continuation of an anomalously low sea ice extent similar to the values for 2008-2010 and below all previous values before 2007. The data show a continuing low value of sea ice extent at the beginning of the summer season and an appearance of a weather pattern (the Arctic Dipole) that tends to favor summer sea ice loss, in contrast to weak and variable summer winds of previous decades. Ocean changes may also be involved. According to the National Snow and Ice Data Center (NSIDC), arctic sea ice extent for June 2011 was the second lowest in the satellite data record since 1979. These new factors over the last several years seem to be holding the September sea ice extent at persistent low values below 5.0 million square kilometers.

The Regional Outlook can help shed light on the uncertainties associated with the estimates in the Pan-Arctic Outlook by providing more detail at the regional scale. We received 7 regional outlooks. With the exception of the Greenland Sea, all regions are expected to exhibit below-average ice extent throughout the remainder of the season.

This month's Outlook reports also include a more detailed discussion of sea ice thickness information provided from field measurements and model results. This year, several airborne campaigns have collected ice thickness or surface topography data in the North American Arctic. Such surveys can help inform predictions of summer and fall ice conditions.

Credit: Arctic Research Consortium of the U.S. (ARCUS).Figure 1. Distribution of individual Pan-Arctic Outlook (July Report) values for September 2010 sea ice extent. Credit: Arctic Research Consortium of the U.S. (ARCUS). Click to enlarge. Download High Resolution Version of Figure 1.