Arctic Sea Ice Discussion 2015: The Melt Season

[stewfox]

Wow, a drop of 137k on the ADS extent yesterday! That takes us into 3rd lowest for the date, below the 2013 minimum and just 91k off the 2010 and 213k off the 2008 minima.

 

 

 

Its going to take a remarkable 'recovery' for not ending up 2nd lowest ever at this rate. Is 2012 under threat probably not.

Edited August 27, 2015 by stewfox

[Gray-Wolf]

Surfs up in Barrow!!! Halocline and this years fresh melt water skim gone. Impacts on refreeze speed this autumn?

[Geordiesnow]

Surfs up in Barrow!!! Halocline and this years fresh melt water skim gone. Impacts on refreeze speed this autumn?

 

For those who may not be aware of the impacts, what do you think the impacts of this could potentially be regarding the speed of refreezing?

[4wd]

Why would there be an impact different from any other year? 
Ice always breaks up there from May to November and I'm pretty sure they get the odd storm every year too.

[Interitus]

Why would there be an impact different from any other year? 

Ice always breaks up there from May to November and I'm pretty sure they get the odd storm every year too.

 

Almost 266,000 km2 lost on ADS (IJIS) extent in past couple of days leaving it now marginally above 2007. Nothing to see here.

[BornFromTheVoid]

We're now below every extent minima bar 2007, 2008, 2011 and 2012.

 

 

The extent loss over the last 2 days was more than twice as large as any other year back to 2002. I'd say 2012 is still out of reach, but 2nd lowest is now a realistic outcome.

[BornFromTheVoid]

Neven's take what the storms mean for multi year ice

[knocker]

I assume this is the remnants of typhoon Atsani which has brought some very dodgy weather early to Alaska?

Edited August 28, 2015 by knocker

[Interitus]

I assume this is the remnants of typhoon Atsani which has brought some very dodgy weather early to Alaska?

 

Supposedly, but sort of - there has been interaction between Atsani and low pressure present over far eastern Russia and the western Bering with a feed of air into the Arctic between them and a large high pressure to the east over the Aleutians. But the actual remnant circulation of Atsani is still present in the North Pacific to the south east of Kamchatka, some distance from Alaska.

[BornFromTheVoid]

NSIDC extent saw a daily drop of 177k, taking it below the minima of 2014, 2013 and 2009, and it's less than 300k away from the 2009 and 2010 minima.

 

The 5 day average extent is now below the minima of 2014 and 2009, and just 16k off 2013, which it will drop well below tomorrow.

[BornFromTheVoid]

ADS extent now guaranteed to achieve at least the 4th lowest minimum on record, having just passed 2008.

 

The 2011 minimum is the next target, a further 222.7k away

 

EDIT 2011, not 2007...

Edited August 31, 2015 by BornFromTheVoid

[BornFromTheVoid]

Here's the composite SLP anomaly for the Septembers that lost of most extent between now and their minimum.

 

 

The composite anomaly for those that lost the least.

 

 

Here's the predicted SLP anomaly for the next week.

 

 

I think the main thing we're looking for now is compression of the pack to enhance extent and area losses. A dipole would work well, but really anything that will push ice from the Pacific side of the Atlantic side would do

[stewfox]

ADS extent now guaranteed to achieve at least the 4th lowest minimum on record, having just passed 2008.

 

The 2011 minimum is the next target, a further 222.7k away

 

EDIT 2011, not 2007...

 

Did you post a graph once re the start of the  refreeze dates last 20/30yrs or at least a link ?

 

Would be interesting to see.

[BornFromTheVoid]

Did you post a graph once re the start of the  refreeze dates last 20/30yrs or at least a link ?

 

Would be interesting to see.

 

I've posted them before based on the NSIDC data, but here it is for the ADS extent, each number represents the date in September of the minimum:

 

1980's Average: 11

1990's Average:  8

2000's Average:   15

2002:   8

2003:   18

2004:   11

2005:   21

2006:   14

2007:   24

2008:   17

2009:   12

2010:   17

2011:   10

2012:   16

2013:   12

2014:   17

Edited August 31, 2015 by BornFromTheVoid

[BornFromTheVoid]

With the latest NSIDC update, the combined 5 day average loss from June 30th to August 31st is the 3rd largest on record, after 2012 and 2007.

 

The 1 day extent is just 54k away from guaranteeing at least the 4th lowest minimum on record (54k of 2008, 12k off 2010), while the 5 day average needs to drop another 134k to achieve the same.

 

Meanwhile, the ADS extent is just 170k off securing the 3rd lowest minimum.

[BornFromTheVoid]

With a drop of 64k yesterday, 2015 is now just 103k of the 3rd lowest minimum on record, and is 2nd lowest for the time of year.

[BornFromTheVoid]

A drop of 138k on the NSIDC daily extent takes us below the 2008 minimum, and over half a million km2 below 2013 and 2014, into the 4th lowest minimum on record and the second lowest extent reading for September 1st. We're now just 131k away from the 3rd lowest minimum, 2011, and just 317k away from the 2007 minimum.

 

The 5 day average just needs to drop another 58k to dip below the 2008 and 2010 minima into the 4th lowest on record, which it might achieve on tomorrows update.

[Gray-Wolf]

So really we appear to be back to the post 07' 'average type summer' losses after a 2 year period of ice retention favouring synoptics?

 

I'm still left very concerned as to just what we will see when the 'perfect melt storm' synoptic trawls around again???

 

Come such a year I really do not see high export/high melt leaving very much ice in the basin at all come Sept?

 

With the slate wiped clean ( all the multiyear gone) how would an 'average type summer' then impact the pack the next melt season?

[BornFromTheVoid]

Agreed GW, it does seems that the loudly proclaimed recovery is over. Despite what really should have been another slow melt, given how cold the melt season started and the most volume since 2009, the warm July was enough to send us back into the bottom 5, possibly bottom 3.

I'd say if we got a mild and high export winter, followed by a 2007 type summer next year, we'd easily drop below 3 million km2 for extent and 2 million for area.

 

Anywho, just a 28k drop for the ADS extent yesterday. That takes us to 77k off the 3rd place minimum, 2011.

[BornFromTheVoid]

Latest update from the NSIDC, with plenty of analysis and images.

 

Steady decline, seasonal minimum approaching

 

August saw a remarkably steady decline in Arctic sea ice extent, at a rate slightly faster than the long-term average. Forecasts show that this year’s minimum sea ice extent, which typically occurs in mid to late September, is likely to be the third or fourth lowest in the satellite record. All four of the lowest extents have occurred since 2007. In mid-August, Antarctic sea ice extent began to trend below the 1981 to 2010 average for the first time since November 2011.

 

More here http://nsidc.org/arcticseaicenews/2015/09/steady-decline-summer-minimum-approaching/

[Benjamin]

Hi BornFromTheVoid!

 

Quick question cuz I'm a bit of a newbie. I've been using the data on the following website to monitor the arctic ice, and it seems to be in contradiction to your own updates. Is the 'area' it records different to 'extent', or am I missing something? The figures seem slightly more positive than your own, so I suppose that's something to be thankful of!

 

http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html

 

Also, just want to thank you for your contributions to this forum. It's truly fascinating, and you're doing a remarkable job in your unbiased reporting, considering the charged views surrounding this topic.

[BornFromTheVoid]

Hi BornFromTheVoid!

 

Quick question cuz I'm a bit of a newbie. I've been using the data on the following website to monitor the arctic ice, and it seems to be in contradiction to your own updates. Is the 'area' it records different to 'extent', or am I missing something? The figures seem slightly more positive than your own, so I suppose that's something to be thankful of!

 

http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html

 

Also, just want to thank you for your contributions to this forum. It's truly fascinating, and you're doing a remarkable job in your unbiased reporting, considering the charged views surrounding this topic.

 

Thanks, Benjamin.

 

Yep, area and extent are different. Basically, for all sea ice measures, the Arctic ocean and surrounding seas are split up into a fine grid of small cells, varying between about 3x3km² up to about 15x15km². The sea ice concentration data is then applied, and the grid cells can be used to calculate the coverage in km² in different regions.

 

When calculating "extent", any grid cell that has more than 15% ice coverage is counted as completely filled. So say a grid cell covers 20x20km of ocean. If that cell is covered by 15%, 50% or 80% sea ice, extent will consider it as completely covered, 400km² of ice. But once it drops below 15%, it's counted as completely ice free, 0km² of ice. This is done for every cell in the Arctic and surrounding seas, with the results added up to give the northern hemisphere sea ice extent value.

 

Now with area, the percentage of ice within the cell is considered, rather than just empty or full. It still uses the 15% cut off though, so anything less than 15% covered is considered empty. The difference with extent lies in the concentration values between 15 and 100%. So with area, if you have three 20x20km cells that are 15%, 50% and 80% covered in ice, area will consider them 60km², 200km² and 320km² sea ice area.

 

So for comparison

 

Cell ...Concentration ....... Extent ..... Area

1............10%... ............... .0km2 ...... 0km2

2............15% . ................400km2 ... 60km2

3............50%. ................ 400km2 ...200km2

4............80%.................. 400km2 ...320km2

5.............100% .............. 400km2 ...400km2

Total .............................1600km2 .. 980km2

 

Most of the cells around the edge of the ice pack have will have concentration values between 15 and 100%. For these, the extent values will thus always be larger than the area values, which means that the overall northern hemisphere extent is always larger than the area.

 

The NSIDC page explains the difference between area and extent too. It's more clear than my own explanation, so very much worth a read.

http://nsidc.org/arcticseaicenews/faq/#area_extent

[Benjamin]

Great! Thanks, much appreciated.

 

 

[BornFromTheVoid]

The 5 day NSIDC extent is now equal to the 2008 minimum and below the 2010 minimum, which means we've now reached at least the 4th lowest minimum on record. The next minimum is 2011, which is 241k away. We're now more than 1.9 million km2 (29%) below the 81-10 average

[Singularity]

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=3100

 

A very good post by Dr. Jeff Masters covering the Arctic sea ice melt season so far, including the nasty storm at the end of August, and looking ahead to the rest of this month.

 

This quote from Steven Cavallo (a University of Oklahoma meteorologist who specialises in polar weather) caught my eye:

 

“There are a lot of TPVs around, meaning the potential for surface cyclone formation is high, so I think the forecast sensitivity is very high right now and there could still be some significant ice loss.â€

 

It's then mentioned that there's a lot of uncertainty regarding storm formation in the next week or so, and how this could be related to unpredictable tropical cyclone impacts as the systems recurve and engage with the polar jet stream.

 

 

This is followed by some discussion of the sea ice 'health' and another quote catches my eye, this one from Polar climate specialist Jennifer Francis (of Rutgers University):

“Much of the ice that's left is either slushy, severely broken up, or covered in melt pondsâ€.

 

There is then an interesting discussion of the potential for the El Nino 'mild winter for northern USA and Canada' signal across North America to be combated by a reverse signal driven by the high ice loss on the Pacific side of the Arctic. Could the Arctic forcing possibly override the tropical forcing?