Tuesday, 30 July 2013

Arctic sea ice

Reflections on Arctic sea ice surprises...

Paul Beckwith


29 July, 2013

1) The cyclone that just passed through the Arctic was much weaker than the US navy sea ice motion projections and GFSx/ECMWF forecasted. http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicespddrf_nowcast_anim30d.gif


2) Although sea ice volume must still be dropping, the cyclone pushed the ice apart. http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif When highly ridged, thick ice is pushed apart, the sea ice area (defined as the region with 100% concentration) can actually flatten or even increase. This flattening can be observed in the Japan satellite date: http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm


3) Sea ice extent (defined as regions with ice concentration >15%) still decreased according to NSIDC http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png but was shown to flatten and even INCREASE according to DMI. http://ocean.dmi.dk/arctic/plots/icecover/icecover_current_new.png (image shown below).


4) The sea ice seems to be dictating the local weather above the Arctic more than the atmosphere. The larger surface area of ice (from all the fractured chunks) is undergoing rapid melt but the whole blob of ice is perhaps suppressing large cyclones.


5) The ice behavior this whole melt season is turning out to be very different from what we have seen in the past. Namely, the massive cracking and fracturing back in March, the persistent cyclones in May and June gouging out greatly thinned ice regions around the north pole, and now the resilience of the ice during the latest cyclone (and perhaps suppression of a large cyclone like last year)



6) Bottom line. Greatly fractured ice seems to be more durable to cyclones than expected, or even changing the ocean/atmosphere/ice system to suppress such cyclones. It appears that the ridged ice just north of the Canadian Arctic archipelago (that people mislabel as multi-year ice (MYI)) is spreading out in an effort to save the rest of the pack. I appears that my prediction of zero sea ice at the end of this season may be a spectacular fail!!! Still another 6 weeks of melt left to go, so we continue to observe in awe:) Fascinating stuff...



From Sam Carana:

Also have a look at the animation I added at the bottom of the post at http://arctic-news.blogspot.com/2013/07/arctic-cyclone-july-2013.html (shown below) showing the cyclone's huge impact on sea ice concentration.

 Also, have a look at http://arctic-news.blogspot.com.au/2013/07/open-water-at-north-pole.html which concludes that, while satellite images may indicate that the sea ice is still several meters thick in many locations, huge amounts of surface water may be present on top. 

The albedo of water is far lower than ice, so less sunlight is reflected back into space and a lot more heat is absorbed by the water, further accelerating the sea ice melt. 

This spells bad news for the remaining sea ice, since the melting season still has quite a bit of time to go.


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