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Tuesday, November 18, 2008

The 2007 Spike in Arctic Ocean SST


The reasons for the drastic decline in Arctic Sea ice during 2007 include the reversal of Arctic Ocean currents, polar amplification exacerbated by of a string of El Nino events (2002/03, 2004/05, 2006/07) with no La Ninas to counteract them, the Arctic Oscillation, and others. Emphasizing the magnitude of that decline, the Arctic Ocean SST anomaly graph in my post Optimally Interpolated SST (OI.v2 SST) versus Extended Reconstructed SST (ERSST.v2) Data showed a significant spike in Arctic Ocean SST in 2007. To save you a click, the following is a graph of OI.v2 SST anomaly data for the Arctic Ocean [65N-90N] from November 1981 to October 2008. It clearly shows the anomalous 2007 rise in SST.
Figure 1

The majority of the unusual sea ice loss in 2007 took place in and north of (moving west to east from Siberia to the Alaska-Canada border) the Laptev Sea, the East Siberian Sea, the Chukchi Sea, and the Beaufort Sea. Refer to the following video (MOV format, 5.66MB) of the 2007 Arctic melt season.


Figures 2 and 3 illustrate how I divided the Arctic Ocean SST anomaly data into quadrants. The coordinates I used isolate most of the affected area.
Figure 2
Figure 3

Figure 4 shows the Arctic SST anomaly data (OI.v2 SST) from November 1981 to October 2008, with the data divided into the quadrants shown above. Sorry about the weight of the curves, but if they were heavier, the forward curves would hide those behind. The 2007 spike in SST anomaly took place in the area identified as “Siberia-Alaska”, the purple curve, confirming that the spike in SST simply reflects the unusual ice loss north of Eastern Russia and Alaska.
Figure 4

But the 2008 Arctic sea ice loss was nearly the same as 2007, yet in 2008, Arctic SST in that area did not climb to the 2007 temperature. The sea ice loss in 2008 appears to have been more evenly distributed than it was in 2007. Refer to Figure 5, which are comparative sea ice maps near the peaks of the melt season, September 15, 2007 and 2008.
Figure 5


Comparative sea ice maps are available from Cryosphere Today:

Optimally Interpolated Sea Surface Temperature Data (OI.v2 SST) is available through the NOAA National Operational Model Archive & Distribution System (NOMADS).

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