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Messages - Rubikscube

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Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 07:43:00 AM »
How did the 2012 GAC look on false color as a comparison?  I am a relative newby and did not start following the melt season till a couple of years later.  Is that available to look up on the Bremen site?

You can find the live coverage of the GAC 2012 in the archives of Neven's blog. There are several Uni-Bremen false color gifs for comparison there. Ice concentration was notably lower in areas affected by that storm, which I believe make a lot of difference to the outcome. Powerful August storms in 2013, 2014 impacted high ice concentration areas and had much the opposite effect of GAC-2012. It is interesting to see what the impact will be of this storm.

Arctic sea ice / Re: The 2020 melting season
« on: July 07, 2020, 11:42:31 AM »
OK...what is epic about the 10 day forecast? I see a temp forecast at 850 hpa. Google tells me this is generally about 1.5km above sea level, above the boundary layer.

If I open the GFS forecast and look what's doing in 10 days at sea level, I see the warm spots wherever this is open water in the forecast and all the ice covered areas are actually pretty mild at 0.0 - 1.0C.

The surface temperature of melting ice is always going to be zero until the ice has melted and turned into water - that's thermodynamics - therefore surface temperatures from the ice are not going to tell you anything about how fast the ice is melting. That is why we use 850 hpa temps, because they are not affected by the ice and can tell you something about how much heat there is in the atmosphere. Yes, 850 hpa is 1.5 km above the surface and can in rare instances be misleading, but you'll need a very concrete reason to think so. Peolpe will even use 500 pha temps sometimes.

Regarding 2013 pole melt. 2013 had the exact opposite setup of what we have now. Back then a very persistent cyclone stuck around the north pole for so long that the ice dispersed to the point that it became visible in satellite images (for the same reason that the current anti-cyclone is compacting the ice). Fresh from the GAC-2012 a lot of people, myself included, thought this would spell doom for the ice, but as is usually the case, the cyclone kept the temperature low and actually helped preserve the ice (2013 was by all metrics a huge recovery from the year before). What we see in images right now is ice at the north pole melting in-situ. What we see in images from 2013 is ice at the north pole dispersing from wind action. 

Arctic sea ice / Re: The 2020 melting season
« on: July 04, 2020, 07:41:33 PM »
2014 had a similar HP pattern, so comparisons are somewhat warranted. The big difference is that back then there where no heat import, just cold air circling around. 850 hPa temps were 5-10 C lower than they are now, and there was a lot of snow in the buoy-pictures which took forever to melt (the buoy thread seems dead now. I've been away for a while so I don't know why, but the 2014 pics will still be there for comparison). I think this is a pretty uniquely awful setup which does not come around very often. Unprecedented in the post-2007 era.

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