Below is an animation with temperature anomalies for the period September 8, 2011, to October 7, 2011.
[note: animation is a 1.72 MB file and may take a while to fully load and become visible on the page, especially on slower connections. Keep the page going for a while if it does'n immediately show up animated.]
As the animation shows, temperatures can differ significantly from day to day. As described in a previous knol, such high temperature anomalies are suggested to be caused partly by methane releases from hydrates. This is supported by the fact the the origin of the methane appears to be in the Arctic ocean.
Above images may suggest that temperature anomalies do not go beyond 4°C. However, anomalies of more than 4°C are not uncommon in the Arctic Ocean, as shown on the animation below, based on data from JAXA/EORC and displaying sea surface temperature anomalies over the past few months.
Possible causes of these Arctic temperature anomalies
As Sam Carana suggests, such anomalies could well be caused by methane from submarine hydrates. This methane gradually moves away from the emission points with the wind, at times causing even larger temperature anomalies elsewhere, e.g. on Baffin Island, Canada, which showed an anomaly of over 12°C in November 2010.
For more specific moments of the day and specific locations, the anomaly can be even more striking. As an example, on January 6, 2011, temperature in Coral Harbour, located at the northwest corner of Hudson Bay in the province of Nunavut, Canada, was 30°C (54°F) above average, according to:
In conclusion, temperature anomalies in the Arctic can exceed 10°C and it is hard to explain such large temperature anomalies without including methane as a cause.
Further possible causes of these Arctic temperature anomalies
Shallow seas warm up more rapidly than deep seas. There has been a dramatic warming of the bottom water layer over the eastern Siberian shelf coastal zone (<10 m depth),since the mid-1980s, by 2.1°C. This could possibly cause these temperature anomalies.
However, as the animation below shows, there was little or no violent warming in the East Siberian Sea on this day, like in some other areas of the Arctic, despite the fact that the East Siberian Sea is rather shallow.
[note: animation is a 1.9MB file and may take a while to fully load and become visible on the page, especially on slower connections. Keep the page going for a while if it does'n immediately show up animated.]