Quote:
Originally Posted by nei
giving a few thoughts, I think I want to add a bit more detail. I'll do so tomorrow when I'm more awake.
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Ok here are some of my thoughts on possible weather effects. First a couple of facts:
1) Ocean covered with ice, especially thick ice, doesn't exchange heat or water vapor with the atmosphere. The atmosphere and ocean becomes disconnected
2) If the ocean is open, the ocean can exchange heat with the atmosphere. As well as water vapor.
3) Ocean with a mix of ice and water must be at the freezing temperature (which isn't exactly 0°C due to salt). The air near the surface will also be close to water temperature
As fall progresses the temperature of the Arctic will drop as incoming sunlight falls to near zero. Any open ocean lying around will be much warmer than land. The air above the open ocean will be kept much warmer and wetter than elsewhere. The extra moisture and temperature contrast could provide a fuel for big storms. Might we see any unusual arctic storms this autumn?
The open ocean dumping heat and evaporating water vapor will make the ocean cool much faster than it were covered with sea ice. So in a way, a lack of ice encourages a return to sea ice conditions quickly in wintertime conditions. Cooling and refreezing all the open ocean this autumn will add some extra heat to the atmosphere that it doesn't usually get.
As many here already know well, the North Atlantic / Arctic Oscillation played a major role in affecting recent winters in the northern US. Its strength is determined by the pressure difference between the Arctic (or subarctic North Atlantic) and the subtropical Atlantic. A larger pressure contrast generally means less airflow between the Arctic and lower latitudes with Arctic air trapped in. If the Arctic is warmer, the pressure contrast will be weaker and weather patterns change. But by winter, most of the Arctic ocean will have refrozen so low sea ice shouldn't make much difference. The Arctic lows/ highs have the biggest impact in winter. But I saw a post saying it might have had a summer effect.
Found since the start of unusually low of Arctic sea ice (2007):
Dosbat: Summer Daze 2012.
The pattern I showed consisted of strongly anomalous high pressure over Greenland surrounded by a ring of tendency to low pressure anomalies...As could be seen from the original Summer Daze post, this process shows that the pattern doesn't occur regularly in the past in the way it has done since 2007.
Unusually low pressure in the UK means colder, wetter weather as weatherfan2 is well aware. I'm not sure I'm convinced; is the pressure pattern caused by the low sea ice or are the same weather patterns responsible for low summer sea ice also causing the pressure differences?
If enough summer sea ice melts… Open ocean absorbs most of the sun's energy (>80%); ice doesn't (< 20%). The incoming solar radiation into high latitudes is high, really high right around the solstice. Before clouds, on June 21st, the poles get
more solar radiation per area than the tropics. See the first graph
I made in this post. But by late August, the sun is too low to make much of an effect. But if sea ice got low in July, there's a potential for a large amount of extra heat to be absorbed that won't usually. Assumming it's not so cloudy much of the sunlight never makes it to the ocean. The Arctic (and many high latitude oceanic locations) is usually cloudy in the summer and maybe more open ocean could make it even cloudier so the effect could be limited. Otherwise, extra heat in an unusual spot would affect air circulation patterns, maybe it could create weather not seen before, at least in recent human memory. Of course, if there's any sea ice remaining in a mostly open ocean in July, any extra heat would be used to melt more sea ice.