Geoscience Reference
In-Depth Information
2007
2008
+50
+25
2009
2010
0
-25
2011
2012
-50
Figure 7.16.
Mean September ice extent (all colored regions) and anomalies in ice
concentration (in %, see color bar) for the years 2007 through 2012, based on satellite
passive microwave data. The median September ice extent is shown by the purple line.
Concentration anomalies and median extent are both referenced to the 1979-2000
period, which includes data from SMRR. This accounts for the larger “polar hole” of
no data coverage compared to the SSM/I SSMIS period 1987-present(courtesy of W.
Meier, NSIDC, Boulder, CO). (See plate section for color version.)
largest for September, the end of the melt season. This has been attended by gen-
eral thinning ice the ice cover. However, a closer look at the record reveals that the
September trend in total Arctic sea ice extent (
Figure 1.6
), as well as trends in other
months, is superposed on large variability from year to year; and this strong year-to-
year variability in total extent is accompanied by especially pronounced variations
