(Image source: DMI)
Earlier this week, a moderate-strength Arctic Cyclone formed near Svalbard. Since that time it has persisted even as it drifted into the Laptev sea as a 1000 mb low today. Now, according to forecasts, the storm threatens to remain in the region for at least the next ten days, deepening to as strong as 980 mb and chewing into a region of sea ice that has been consistently weakened by storms since late May.
If you’ve followed this blog and feel you’ve heard this story before, it’s because you have. PAC#1 formed in late May and churned through the central sea ice all throughout June, creating anomalous thinning of a region near the North Pole and on toward the Laptev sea. By early July, the storm had finally petered out, but not after leaving behind a wreckage of thinned and broken sea ice.
Now, it appears a second storm (PAC 2013 #2) is set to churn through the same regions so drastically impacted by PAC 2013 #1, this time lasting for at least two weeks.
So here we go again:
(Image source: ECMWF)
The above image shows a strong 980 mb PAC 2013 #2 over the Beaufort Sea on July 24th. Current model runs show the storm moving back and forth over the Central Arctic, Beaufort and East Siberian Seas until at least July 29th.
Warm Storm Takes Hold
As sea ice is much thinner and as atmospheric and ocean temperatures are much warmer, it is likely that a new Persistent Arctic Cyclone will have even more obvious and far-reaching effects than the one we witnessed in June. Average surface atmospheric temperatures throughout the Arctic are above the temperature at which ocean water freezes and almost all regions show temperatures above 0 degrees Celsius. So precipitation in these storm events is more and more likely to fall as rain.
You can view how much the Arctic has warmed in the composite weather map below:
(Image source: Uni Koeln)
Note the large pulse of 78-86 degree (Fahrenheit) weather (24-30 degree Celsius) pushing all the way to the Kara Sea near Archangel and points eastward. Meanwhile, 40-50 degree (Fahrenheit) temperatures have become common in areas near Svalbard, the extreme north coast of Greenland, and even during the daytime over some sections of the Beaufort (not visible in the current shot above). We can also see a number of wildfires raging in the heatwave stricken region of Arctic Russia (fire sites on the map are indicated by vertical black lines with squiggles on top).
Overall, temperatures over the Arctic Ocean have averaged 1-3 degrees Celsius above normal. With most of the summer spent in cloudy, stormy conditions that usually lead to cooler weather, this year is highly, highly anomalous. What we have, instead, are warm storm conditions.
With all this heat in place, wet, rainy precipitation is much more likely to fall over areas of the Central Arctic underneath the new storm. As water carries more heat energy than air, a warmer than freezing rainfall over the ice sheet is a powerful melt enhancer. In addition, associated winds are likely to further shatter and disassociate ice beneath it. Eckman pumping forces will also be more likely to access warmer waters beneath the colder, fresher layer that tends to protect the ice. This is due to the fact that a constant sunlight has now streamed through the ice for two and half months running. This long duration sunlight is likely to create a warmer water layer in a range of 40-70 feet beneath the surface. A passing storm of moderate to strong intensity will likely be able to access this warmer layer and transport it to the surface where it can do work melting ice.
A somewhat stark example of what a warm storm can do to thin, fragile sea ice is also now plainly visible via APL’s North Pole Camera #2. Even since yesterday we can see that melting has rapidly advanced around the camera as it now rests in a deepening and expanding melt lake stretching far about in all directions:
(Image source: APL)
From this shot, only a small band of remaining snow cover now surrounds the buoy in the foreground. It also appears that the camera itself is now sitting in the water. It is worth noting that this melt lake currently rests on ice that is probably between 1 and 2 meters in thickness. But the waters now covering the ice are darker, absorbing more direct and indirect sunlight even as the above-freezing melt lake slowly bores down into the ice. If the Eckman pumping forces engaged by this storm are also bringing warmer waters up from the depths, the ice near this camera is suffering melt from both above and below.
Though the current picture shows somewhat sunny weather, conditions near the camera have been mostly stormy for the past three days. It is likely that storm conditions will soon return as this region is mostly engulfed in cloud.
Sea Ice Measures Near Record Lows
Major sea ice monitors now show ice area, extent and volume all falling rapidly. Sea ice extent, according to NSIDC is at about 7.8 million square kilometers — or 4th lowest on record. Cryosphere Today also shows sea ice area tied for 4th lowest on record with about 5.5 million square kilometers of sea ice area remaining. Area losses in this measure have been particularly cliff-like with nearly 400,000 square kilometers lost in just two days. Similar losses over the next 5-6 days would bring the monitor into new record low territory. By mid June, PIOMAS showed the sea ice volume measure running at about 3rd lowest on record with rapid losses ongoing since late May.
Though these values still remain above record lows, there is a huge amount of heat energy moving around in the Arctic. Earlier this year, the sudden amplification of the heat in May led to the fastest snow melt on record. Snow cover at the end of April was 9th highest. By the end of May, snow cover levels had plummeted to 3rd lowest. The fact that the Arctic is capable of such dramatic swings is clear proof that the heat balance there has reached highly unstable levels. It is for these reasons that we must remain alert for the potential of rapid ice loss as July transitions into August.
Despite a slow early May sea ice melt (in contrast to a racing snow melt), rates of loss have been near record levels throughout June and July of 2013. Given this break-neck melt pace and a state of continued fragility throughout the ice pack, risk remains high that one or more measures will see new record lows come September. Sea ice is now also very highly dispersed making it even more vulnerable to melt and disruption. The most recent Crysophere Today shot shows broad regions where sea ice concentration is now 60% or less.
(Image source. Cryosphere Today)
With such broad areas of ice so vulnerable and exposed, any further thinning, melt and dispersal caused by the re-emergence of a warm storm is likely have strong impacts with the potential to dramatically affect final melt totals.