Arctic Sea Ice Extent, Area, and Volume

[etudiant]

I don't understand why there is this belief in linear models.

Everything we know about climate and weather says jumps are the norm, not slow and gradual transitions from one state to another.

So why would we expect arctic ice to behave differently? Based on precedent, we should bump around a record low for a while .

Then, if the environment remains favorable, we jump to a zero late summer ice regime. The Viking records suggest as much.

The real question is whether this is a cyclical or a secular development. Does anyone have any substantive input towards answering this question?

[ORH_wxman]

3 hours ago, etudiant said:

I don't understand why there is this belief in linear models.

Everything we know about climate and weather says jumps are the norm, not slow and gradual transitions from one state to another.

So why would we expect arctic ice to behave differently? Based on precedent, we should bump around a record low for a while .

Then, if the environment remains favorable, we jump to a zero late summer ice regime. The Viking records suggest as much.

The real question is whether this is a cyclical or a secular development. Does anyone have any substantive input towards answering this question?

There is a cyclical pattern on top of the underlying anthropogenic warming. The Arctic is kind of a tough one though because it has previously responded to global temperature changes much more rapidly than other regions...so we don't have a great idea on how it will behave with added anthropogenic warming. We do know that it warmed about 5x the rate of the rest of the globe in the early 20th century and cooled about 5x the rate during the cooling period 1940-1970...and recently it has warmed about 10x faster than the rest of the globe. There's probably been some natural warming helping out since the mid 90s when the AMO flipped on top of anthro warming. 

 

As for the ice, there was a paper that came out (Tietche et al) in 2011 that had looked at what happens when we approach an ice-free state and if it caused any "tipping point". It found that it did not...it actually found the opposite conclusion...which suggested as we get closer to ice free, it may take longer to get that final push than it did to go from 1990s levels to 2007 levels of ice. It showed that winter temps need to be about 2-3C warmer than currently (or maybe another 1-1.5c if you just use last winter's excessively warm temps) to consistently have a great chance to melt all the ice out in summer using model projected 2050 temps. Now, maybe this is too optimistic for the ice...it has shrunk faster than previous models said it would so we will have to see if that trend continues...or if the flattening happens. There's some recent argument for both cases...on the one hand, we have basically a flat trend in area/extent since 2007 and we've seen rebounds following record lows which follows the Tietche et al theory, but the volume trend is still downward too so will there some "flash melting" type event? Maybe...if we keep the volume trend down, then yeah it could happen pretty soon. But we've seen volume rebounds after records so of the same happens after this season, then it will probably push the ice-free date back another couple years. 

[nzucker]

8 hours ago, ORH_wxman said:

Yeah the vortex is mostly hanging out over the CAB...there's a pretty strong storm in the couple days...we'll see if that is strong enough to do any damage. But it is definitely not the typical pattern for huge melting out shown through mid-month.

The biggest enemy of the ice is how thin it was at the beginning of the year. If this pattern happened in 2015, we probably would have seen a minimum extent in the mid 5s.

 

There are windy conditions as the low bottoms out near 980mb but also a cold core of -10C 850s near the NE Beaufort as well as uniformly below freezing 850s across the Arctic to balance it out. The ECM/GFS take the deep vortex out towards August 15th, becomes difficult to see huge losses as we approach the second half of August. A lock now that area and extent finish above 2007 and 2012, probably 2011 as well. 

[bluewave]

14 hours ago, WidreMann said:

I would trust the dynamical more than the statistical, because we are in uncharted territory here. Even so, it looks like the median of those models would still be above 2012.

We missed our chance to beat 2012  when the strong dipole pattern of 2007-2012 failed to emerge in June. So the 2012 extent record will remain safe another year. The HadGem model did a great job back in 2012 showing a slower rate of loss vs the extreme 2005-2012 loss rate.

 

I am wondering if the dramatic dipole reversal following the historic 2007-2012 rapid melt seasons is a result of the weaker AMOC?

 

http://nsidc.org/arcticseaicenews/

In the far northern Atlantic, warm water flowing northward from the tropics is cooled by the atmosphere, becomes denser, and eventually sinks to great depths. The descending water is key in driving a sub-surface and surface ocean circulation system called the Atlantic Meridional Overturning Circulation (AMOC), which is part of the global ocean conveyor belt of heat and salinity. Where the Atlantic water sinks has a very important effect on the climate of Northern Europe; the heat that the ocean loses to the atmosphere is what keeps Northern Europe quite warm relative to its latitude. For example, Amsterdam is at the same latitude as Winnipeg, Canada, but experiences much warmer winters.

Based on a recent modeling study, Florian Sévellec and colleagues propose that the ongoing loss of Arctic sea ice may disrupt the AMOC. The sea ice loss leads to a freshening of the northern North Atlantic and stronger heat absorption at the surface. This means that waters in the northern North Atlantic are less dense than they used to be, which has the effect of providing a cap, or lid, that may inhibit the northward flow of warm waters at the surface and the eventual sinking of these waters. The authors suggest that the Arctic sea ice decline may help to explain observations suggesting that the AMOC may be slowing down, and why there is a regional minimum in warming (sometimes called the Warming Hole) over the subpolar North Atlantic.

 

 

 

 

[ORH_wxman]

51 minutes ago, bluewave said:

We missed our chance to beat 2012  when the strong dipole pattern of 2007-2012 failed to emerge in June. So the 2012 extent record will remain safe another year. The HadGem model did a great job back in 2012 showing a slower rate of loss vs the extreme 2005-2012 loss rate.

 

I am wondering if the dramatic dipole reversal following the historic 2007-2012 rapid melt seasons is a result of the weaker AMOC?

 

http://nsidc.org/arcticseaicenews/

In the far northern Atlantic, warm water flowing northward from the tropics is cooled by the atmosphere, becomes denser, and eventually sinks to great depths. The descending water is key in driving a sub-surface and surface ocean circulation system called the Atlantic Meridional Overturning Circulation (AMOC), which is part of the global ocean conveyor belt of heat and salinity. Where the Atlantic water sinks has a very important effect on the climate of Northern Europe; the heat that the ocean loses to the atmosphere is what keeps Northern Europe quite warm relative to its latitude. For example, Amsterdam is at the same latitude as Winnipeg, Canada, but experiences much warmer winters.

Based on a recent modeling study, Florian Sévellec and colleagues propose that the ongoing loss of Arctic sea ice may disrupt the AMOC. The sea ice loss leads to a freshening of the northern North Atlantic and stronger heat absorption at the surface. This means that waters in the northern North Atlantic are less dense than they used to be, which has the effect of providing a cap, or lid, that may inhibit the northward flow of warm waters at the surface and the eventual sinking of these waters. The authors suggest that the Arctic sea ice decline may help to explain observations suggesting that the AMOC may be slowing down, and why there is a regional minimum in warming (sometimes called the Warming Hole) over the subpolar North Atlantic.

 

 

 

 

 

The cold pool in the North Atlantic also really expanded and intensified in 2013 which was right after the huge Greenland melt in 2012...so I wonder if that was at least partially related. 

[bluewave]

12 minutes ago, ORH_wxman said:

The cold pool in the North Atlantic also really expanded and intensified in 2013 which was right after the huge Greenland melt in 2012...so I wonder if that was at least partially related. 

It could also be related to why the Siberian October snow signal hasn't worked in recent winters with the stronger PV and more +AO/+NAO.

[franklin NCwx]

Looking over the models and the vortex lasting past mid month is this likely an early end to the melt season?

[bluewave]

Early dip near freezing with the strong polar vortex similar to 2014 and 2013.

 

 

 

[etudiant]

I'd thought the air temperature was not as significant as the water temperature in driving the amount of melting in the Arctic. Is this a misperception?

[chubbs]

1 hour ago, etudiant said:

I'd thought the air temperature was not as significant as the water temperature in driving the amount of melting in the Arctic. Is this a misperception?

Yes, in August most melting is from water below the ice. Of course colder air cools the water also. Last season saw strong late season melting due to storminess even though temperatures were cool.

[Sophisticated Skeptic]

long range looks pretty mild. 

[bluewave]

Recent cooler temps and stronger polar vortex let 2017 fall a little behind 2007 over the last few days.

 

 

 

 

[raindancewx]

The AMO really does seem to have tremendous influence on the ice extent on Aug 1, or it is an amazing coincidence, I got an r-squared of 0.44 for annualized AMO to Aug 1 sea ice extent. The sun is a weak predictor of sea ice extent change for Aug 1 - Peak extent, but the AMO was still correlated at 0.22 r-squared. The AMO has been trending much lower than last year since June, so that coincides well with relatively little ice lost from the peak date (which varies) to Aug 1. Peak to Aug 1 losses are the lowest since 2006.

Sunspots & AMO, when annualized correlate at 0.06 for 1979-2016, so that's kind of weird in its own right.

The AMO seems to have been hot (>=0.2) on an annual basis 11 times in the prior warm cycle (~1926-1963), so would suspect we're almost done with these super warm years, there are probably two more shots in an AMO sense at breaking the 2012 record, assuming it doesn't happen in 2017, before 2020-2030 when the cold AMO sets in and slows/reverses the trend in declining ice. 

Super Warm Years (>=0.2) 1926-1963: 1932, 1933, 1937, 1938, 1944, 1945, 1951, 1952, 1953, 1958, 1960

Super Warm Years (>=0.2) since 1994: 1998, 2003, 2004, 2005, 2006, 2010, 2012, 2016, 2017* (probably)

The AMO years under -0.10 average 8.786 million km^2 sea ice extent on Aug 1, the AMO years over +0.10 average 7.397 million km^2 sea ice extent on Aug 1, so some kind of slow down seems possible even with the Earth is warmer in the 2020s, back to maybe the late 1990s / early 2000s level?

[bluewave]

There has traditionally been a relationship between Arctic sea ice and the AMO as we have seen with the decline in the 20's and 30's. More specifically, the region south of Greenland seems to have the largest influence on September minimum extent. When those SST's were at their warmest from 2005 -2012, there were three new records set in 2005, 2007, and 2012. The reversal to cooler SST's in this region since 2013 has been accompanied by no new September extent records. You can see the 2005-2012 rate of decline was in a class by itself with nothing else coming close. While that area south of Greenland has cooled dramatically in recent years, the AMO has still remained positive.

 

 

 

[ORH_wxman]

We have a pretty compact ice pack right now...area is running about 6th lowest but extent is flirting around the 3rd lowest mark right now only above 2007 and 2012 though on a few of the data sources it is a bit above 2016 as well. 

My guess is that we may see extent loss slow some at some point and area loss pick up a little more or at least pick up relative to extent loss. Most of the years with similar compactness right now saw some noticeable slowing of extent loss. 

We have a pretty strong storm right now in the Arctic and it is late enough in the season that perhaps it could do some damage. Kind of like the 2012 cyclone but less extreme since it is both weaker and the ice this year is not as in bad shape as 2012 was before that cyclone hit. We will see if it damages the ice enough to cause a late season cliff in extent loss. I'm probably leaning against anything huge though given the higher area right now...but you never know. If we form a potent dipole late in August that helps compact the ice more we could see big extent loss anyway like we saw in 2015 (that year ended on a huge extent cliff even while area loss was light) 

 

[forkyfork]

the loss of CT data really puts a damper on tracking 

[ORH_wxman]

2 hours ago, forkyfork said:

the loss of CT data really puts a damper on tracking 

NSIDC (CT SIA's source) is still transmitting SSMI/S and wipneus posts it...but it is really annoying that we don't have it on the CT SIA graph and also their spreadsheet which made it easy to look up. 

But area right now sits at 4.03 million sq km. That would be 7th place...barely under 2010 .

Other years:

2016: 3.70

2015: 3.79

2014: 4.55

2013: 4.31

2012: 3.09

2011: 3.56

2010: 4.06

2009: 4.33

2008: 3.89

2007: 3.68

[WidreMann]

9 hours ago, forkyfork said:

the loss of CT data really puts a damper on tracking 

What's the CT data?

[ORH_wxman]

10 minutes ago, WidreMann said:

What's the CT data?

Cryosphere Today...it was a webpage from U Illinois that tracked sea ice area from the SSMI/S satellite. NSIDC uses the same one but they don't really show much data on area...all their graphs are extent. CT put the area in graphical format and also in tabular format. But it stopped transmitting data sometime in early 2016...at first they said they were going to be back soon but then the site went dark and it never updated. 

Area is nice to use because it tends to be a better predictor of extent 30-60 days out than extent itself is...but not having CT's easy-to-read data is really annoying. 

[bluewave]

So far it looks like the Arctic storm has slightly slowed the decline rate as the pack appears to be spreading out a bit. The storm has brought an early freeze for the post 2005 Arctic. Right now the extent is tracking between 2007 and 2016 as 2012 pulls further out of reach. 

 

 

 

 

 

[chubbs]

This year's low volume/high NSIDC area status is unusual. Looks like the mild winter is having some impact but is a weaker factor than a slow start to the Arctic Ocean melt season.

[bluewave]

1 hour ago, chubbs said:

This year's low volume/high NSIDC area status is unusual. Looks like the mild winter is having some impact but is a weaker factor than a slow start to the Arctic Ocean melt season.

There may also be a higher degree of uncertainty in the PIOMAS data compared to other years. But we saw how the the PIOMAS and NSIDC extent widely diverged in 2013 compared to the 2007 season. Lower PIOMAS in 2013 vs 2007,but the cool 2013 summer resulted in a much higher higher September extent than 2007.

http://nsidc.org/arcticseaicenews/2017/03/

It was a very warm autumn and winter. Air temperatures at the 925 hPa level (about 2,500 feet above sea level) over the five months spanning October 2016 through February 2017 were more than 2.5 degrees Celsius (4.5 degrees Fahrenheit) above average over the entire Arctic Ocean, and greater than 5 degrees Celsius (9 degrees Fahrenheit) above average over large parts of the northern Chukchi and Barents Seas. These overall warm conditions were punctuated by a series of extreme heat waves over the Arctic Ocean.

Data from the European Space Agency’s CryoSat-2 satellite indicate that this winter’s ice cover may be only slightly thinner than that observed at this time of year for the past four years. However, an ice-ocean model at the University of Washington (PIOMAS) that incorporates observed weather conditions suggests the volume of ice in the Arctic is unusually low.

[ORH_wxman]

Yeah it's actually a pretty compact ice pack right now. I think the cyclone perhaps has just slowed the peripheral melting. 

Though bluewave is correct that typically cyclones over the CAB try and disperse the ice. But the concentration hasn't suffered even if it is doing that. 

[bluewave]

1 hour ago, ORH_wxman said:

Yeah it's actually a pretty compact ice pack right now. I think the cyclone perhaps has just slowed the peripheral melting. 

Though bluewave is correct that typically cyclones over the CAB try and disperse the ice. But the concentration hasn't suffered even if it is doing that. 

Yeah, the record August 2012 storm seemed to be the exception to the rule. 

http://nsidc.org/arcticseaicenews/2012/08/a-summer-storm-in-the-arctic/

Low pressure systems over the Arctic Ocean tend to cause the ice to diverge or spread out and cover a larger area. These storms often bring cool conditions and even snowfall. In contrast, high pressure systems over the Arctic cause the sea ice to converge. Summers dominated by low pressure systems over the central Arctic Ocean tend to end up with greater ice extent than summers dominated by high pressure systems.

However, the effects of an individual strong storm, like that observed in early August, can be complex. While much of the region influenced by the August cyclone experienced a sudden drop in temperature, areas influenced by winds from the south experienced a rise in temperature. Coincident with the storm, a large area of low concentration ice in the East Siberian Sea (concentrations typically below 50%) rapidly melted out. On three consecutive days (August 7, 8, and 9), sea ice extent dropped by nearly 200,000 square kilometers (77,220 square miles). This could be due to mechanical break up of the ice and increased melting by strong winds and wave action during the storm. However, it may be simply a coincidence of timing, given that the low concentration ice in the region was already poised to rapidly melt out.

 

 

[nzucker]

2 hours ago, ORH_wxman said:

Yeah it's actually a pretty compact ice pack right now. I think the cyclone perhaps has just slowed the peripheral melting. 

Though bluewave is correct that typically cyclones over the CAB try and disperse the ice. But the concentration hasn't suffered even if it is doing that. 

I think this storm is less windy than the 2012 event...pressures are a little bit more diffuse, as there is not nearly as much gradient.

Also, 850s are somewhat colder with this storm. There is a large area of -10C 850s and a high concentration ice pack, so there isn't the tearing apart effect that 2012 had on broken up, mushy ice. Instead, the cold is refreezing the periphery and the ice may spread out a bit.

[nzucker]

It's impressive to see -10C 850s reaching the Siberian coast with sub-freezing 850s into Scandinavia in mid-August.

The effect of the storm may be more detrimental as it drifts towards Eurasia and strengthens..it's only like 1000mb over the CAB now.

[WidreMann]

On 8/9/2017 at 10:09 PM, ORH_wxman said:

Cryosphere Today...it was a webpage from U Illinois that tracked sea ice area from the SSMI/S satellite. NSIDC uses the same one but they don't really show much data on area...all their graphs are extent. CT put the area in graphical format and also in tabular format. But it stopped transmitting data sometime in early 2016...at first they said they were going to be back soon but then the site went dark and it never updated. 

Area is nice to use because it tends to be a better predictor of extent 30-60 days out than extent itself is...but not having CT's easy-to-read data is really annoying. 

That's where I used to go all the time, I just didn't know that was the acronym you were using. I do miss it as well. Much more detail and good anomaly charts as well.

[chubbs]

On 8/10/2017 at 0:57 PM, bluewave said:

There may also be a higher degree of uncertainty in the PIOMAS data compared to other years. But we saw how the the PIOMAS and NSIDC extent widely diverged in 2013 compared to the 2007 season. Lower PIOMAS in 2013 vs 2007,but the cool 2013 summer resulted in a much higher higher September extent than 2007.

http://nsidc.org/arcticseaicenews/2017/03/

It was a very warm autumn and winter. Air temperatures at the 925 hPa level (about 2,500 feet above sea level) over the five months spanning October 2016 through February 2017 were more than 2.5 degrees Celsius (4.5 degrees Fahrenheit) above average over the entire Arctic Ocean, and greater than 5 degrees Celsius (9 degrees Fahrenheit) above average over large parts of the northern Chukchi and Barents Seas. These overall warm conditions were punctuated by a series of extreme heat waves over the Arctic Ocean.

Data from the European Space Agency’s CryoSat-2 satellite indicate that this winter’s ice cover may be only slightly thinner than that observed at this time of year for the past four years. However, an ice-ocean model at the University of Washington (PIOMAS) that incorporates observed weather conditions suggests the volume of ice in the Arctic is unusually low.

This year has been cool like 2013 so the volume and extent data are not inconsistent.

[bluewave]

15 hours ago, chubbs said:

This year has been cool like 2013 so the volume and extent data are not inconsistent.

 

Much cooler summer regime since 2013 with low pressure dominating instead of high pressure.

Likely quite a bit of snow has fallen from this Arctic cyclone... Wish the polar bears could report obs [Map: esrl.noaa.gov/psd/people/amy…]pic.twitter.com/nrL6U5LplZ

[Sophisticated Skeptic]

next week's system (980's) could be an ice ripper.   approaching from the warm nose.