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Neven

For those who like that kind of thing (I know I do), I have opened two polls on the Arctic Sea Ice Forum, one for the CT SIA daily minimum and one for the NSIDC SIE September minimum (monthly average).

They're at the top of this list of threads here.

navegante

CAPIE values should drop during the cyclone

http://goo.gl/muUvfj

Also, any thought on the potential Ekman pumping due to this storm, or not relevant at this time? I am no expert at all

Neven

I don't think it's relevant right now, navegante. I believe Ekman pumping requires (lots of) open water.

It's not that strong a cyclone anyhow, but large, yes.

NeilT

I'm wondering if this is correct... It doesn't look like it from the webcam.

http://seaice.alaska.edu/gi/observatories/barrow_sealevel

Jim Hunt

The Barrow ice mass balance buoy is a few miles north of the webcam location, so it's not out of the question. Here's a picture of Barrow beach from May 26th:

http://forum.arctic-sea-ice.net/index.php/topic,1149.msg53090.html#msg53090

You will notice a fair bit of liquid around even then. They are working out the position of the bottom of the ice using the thermistors, which gets tricky once the floe temperature is much as the same as the water underneath it!

wayne

There is nothing in science like repetition,
the horizon shifts in High Arctic Canada were captured many many times near Highest latitude point of USA: Barrow Alaska... You can study it in great details thanks to University of Alaska Archives.

http://eh2r.blogspot.ca/2015/06/from-barrow-strait-to-barrow-alaska-sea.html

Bill Fothergill

An interesting announcement has recently come from NOAA pertaining to the so-called hiatus.

http://www.ncdc.noaa.gov/news/recent-global-surface-warming-hiatus

Jim Hunt

Speaking of which Bill, regular readers of "Tamino" will already be familiar with this graphic graphic of the statistical argument:


https://tamino.wordpress.com/2015/01/20/its-the-trend-stupid-3/

Jim Hunt

And Richard Betts reminds me of this animation from Ed Hawkins:

http://www.climate-lab-book.ac.uk/2013/what-will-the-simulations-do-next/

wayne

Indeed Jim, but to be more specific Global Temperatures variations are due to dynamical meteorology. Of which our greatest latest example in Arctic sea ice was 2013. When our not so bright fake skeptics, ie mainly annoying self proclaimed "pending next ice age" experts, decried sea ice recovery and as it was written "It got colder.....", all the while it really was cloudier by multiple Cyclonic incursions over the Arctic Ocean. The warming factor was still there, it morphed into these incursions which as some may know, were higher energy events, warming symptoms may not be measured only with thermometers. And so from fall 2013 there was an apparent "lull" in sea ice melting, only to be obviously a clever trick by nature to make contrarians look silly.

Rob Dekker

Thank you Neven, for again a great overview of the early melting season. I share your conservative view that the low extent (especially from IJIS) is probably not a significant indicator.

Low ice "extent" and average "area" suggests that the ice pack is compact and does not yet expose much water (melting ponds) in the ice pack, and thus amplification is limited.

Thus,assuming "average" summer weather, I believe that the early melting start may taper off over the next month and get more in line with extent numbers of 2011 and alike.

But the Arctic is notoriously unpredictable, and certainly has a few tricks up her sleeve.

Also, a big THANK YOU to Chris Reynolds, for the May summary post :
http://dosbat.blogspot.co.uk/2015/06/may-2015-status-four-dipoles.html

What a clear and wonderful read, explaining so comprehensively how the air pressure differences over the Arctic affect regional melting patterns.

Hats off !

Rob Dekker

Also, I'd like some clear mind advice on something.

I developed a super-simple model that uses Northern Hemisphere spring snow cover and a metric for melting ponds as a predictor for the September ice minimum :

http://neven1.typepad.com/blog/2013/07/problematic-predictions-2.html

This model works very nicely, as it obtains better correlation numbers than plain extrapolation of the long term trend.

For Northern hemisphere snow cover I use Rutgers Snow Lab monthly numbers, and for "melting ponds" (and other water close to ice) I use NSIDC numbers for (ice extent - minus - ice area) as a metric.

This year, as Neven reports, ice "extent" in May is running very low, while ice "area" is sort of average.

However, and here is the issue :
NSIDC does not seem to share that observation.
Here are the numbers :

..
2012 5 Goddard N 13.11 10.99 --> E-A = 2.12 Capie:A/E= 0.838
2013 5 Goddard N 13.08 11.20 --> E-A = 1.88 Capie A/E = 0.856
2014 5 Goddard N 12.77 10.99 --> E-A = 1.78 Capie A/E = 0.860
2015 5 NRTSI-G N 12.65 10.78 --> E-A = 1.87 Capie A/E = 0.852

Numbers obtained from here :
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/May/N_05_area.txt

So it seems that NSIDC does not really rate May 2015 as specifically high on Capie index, nor out of the ordinary for the "extent minus area" indicator that I use as a metric for "melting ponds" in May.

So, for starters, I wonder why that difference in data sets (between NSIDC and IJIS extent and CT area) came about.

Second, the problem may be related to the way that NSIDC calculates their sea ice "area" numbers. From the same NSIDC txt file I linked above :

The "extent" column includes the area near the pole not imaged by the sensor. It is assumed to be entirely ice covered with at least 15% concentration. However, the "area" column excludes the area not imaged by the sensor. This area is 1.19 million square kilometers for SMMR (November 1978 through June 1987), 0.31 million square kilometers for SSM/I (July 1987 through December 2013), and 0.029 million square kilometers for SSMIS (January 2008 to present). Therefore, there is a discontinuity in the "area" data values in this file at the June/July 1987 boundary and at the December 2007/January 2008 boundary.

which does not really make sense to me.
Is the irregularity on "area" around the dec 2007/Jan 2008 boundary, or around December 2013 ? Or both ?

I'm confused. Anyone know what's going on here ?

Neven

Thanks, Rob.

I need to correct something I've said:

It's not that strong a cyclone anyhow, but large, yes.

I was wrong. It's pretty strong for a cyclone. Not GAC-2012 material, but not exactly weak either. I didn't look at the forecast careful enough. According to Environment Canada the cyclone is at 975 hPa right now, and still dropping:

Jim Hunt

The cyclone was down to 972 hPa in the 06:00 UTC analysis.

http://forum.arctic-sea-ice.net/index.php/topic,1149.msg53445.html#msg53445

Rob's point about snow cover makes we wonder about butterflies flapping their wings in Siberia. How much precipitation will this storm produce, and of that how much will be snow and how much will be rain?

And of course how much will it churn up the ice!

Bill Fothergill

Rob D wrote...

" ... which does not really make sense to me.
Is the irregularity on "area" around the dec 2007/Jan 2008 boundary, or around December 2013 ? Or both ?"

It looks as though someone at NSIDC has done a bit of cut&paste without checking if the paragraph still makes sense.

I was aware of the "pole hole" in coverage, but it has been a couple of years since I actually bothered to read the caveat. The version I have pasted into my spreadsheet states that...

" ... This area is 1.19 million square kilometers for SMMR (from the beginning of the series through June 1987) and 0.31 million square kilometers for SSM/I (from July 1987 to present). Therefore, there is a discontinuity in the "area" data values in this file at the June/July 1987 boundary."

At that time, the correction was pretty unambiguous: one added 1.19 million sq kms to any Arctic area value up to, and including, June 87; after that, one only added 0.31 million sq kms.

I would hazard a guess that, from Jan 2008 onwards, the offset value reduces to 0.029 - but it could certainly have been phrased better.

Does that help?

I have certainly found their helpdesk extremely helpful whenever I have had a query.

cheers bill f




D

Yes, Neven, it is a strong cyclone for June. In 2013 a cold stormy June led to recovery of the ice pack. Stormy Junes over the Arctic ocean are generally associated with recovery years. However, I think we need to be careful to look at the jet stream patterns. In June 2013 the jet stream collapsed around the Arctic ocean keeping cold air in and warm air over the continents. This year the jet stream is very wavy, pulling warm air into the pole.

We need to be careful to look at the details and watch out for generalizations.

Arctic amplification is based on more adsorption of solar radiation as snow and ice melts. Melt ponds are one part of that equation but so are ice extent and area of snow cover over land.

I still expect the large amount of excess heat in the oceans around the Arctic to keep the melt going at a record rate. The rapid loss of snow this spring first on the Alaskan side, now on the Siberian side is contributing to Arctic amplification this summer. However, weather and ice are complex and hard to predict. A stormy June might slow down the progress of melting. It might buy the ice records a little more time. We'll see.

-George aka FishOutofWater

jdallen_wa

Indeed, FishOutofWater.

This isn't the GAC of 2012, but it also isn't the ice-saving weather of 2013.

Currently according to Climate Reanalizer there is rain falling across the Laptev. The next three days show much of the same, with warm wet air streaming across the Kara through the Laptev to the ESS bringing rain and accompanied by temperatures of 1-4C. The remaining snowpack is being obliterated.

In short, there is nothing about this storm which favors the ice.

Wipneus

Rob Dekker,

That data file does not give you what you think it does. Instead of average {extent|area} computed from daily sea ice concentration, it is {extent|area} calculated from average monthly sea ice concentration.
Think of it: even if area equals extent every day of the month - 100% concentration within the ice extent, never any melt ponds or leads- grid cells that are only covered with ice during part of the month lead to an average concentration less than 100%. Thus monthly area < monthly extent.

I think, the monthly E-A may be at least biased by the change in extent in that month, explaining at least some correlation in an obvious way.

Martin Gisser

Jim Hunt,
indeed a graphic graphic! The paradigmatic graph to end all hiatus delusions. Horror of the Lomborgs of our world.

Neven

Cyclone is now at 971 hPa:

Colorado Bob


Seaweed colonizing ice-free parts of Antarctica

With glaciers melting, the original white, mostly lifeless Antarctica is now becoming darker and lively with seaweed.


http://earthsky.org/earth/seaweed-colonizing-ice-free-parts-of-antarctica

Blaine

@Neven, @Navegante:

To the extent that the ice is free-floating, it will not retard Ekman pumping. In fact, by transferring stress downwards, it will increase the depth of the coherently moving surface layer, which will increase the Coriolis deflection angle between the wind and the direction of ice motion, and increase Ekman pumping. Of course, the ice will also retard surface compression (which violates the free-floating assumption), which will decrease net Ekman pumping. The sign of net effect is not obvious, and I don't expect that it would come close to canceling out the effect altogether.

Ekman pumping due to cyclones is not usually significant for a completely different reason: timescale mismatch. Cyclones typically just don't last long enough to see significant thinning of the surface layer. Certainly a repeated series of cyclones in the same location could see a significant effect, but this doesn't usually happen.

Wave-driven vertical mixing on the other hand, is non-linear in the applied force and is severely depressed in ice-covered regions. So Neven's conclusion that vertical mixing caused by a cyclone is very much less where there is significant ice cover is absolutely correct, even though this is not caused by a an Ekman pumping effect.

In any case, there is very little heat available at middle depths at this time of year, so I would not expect to see a significant melting effect now.

What would be possible now is a significant increase of open water caused by ice compression. By causing surface divergence and convergence areas, the the storm should crunch some surface ice together. Ice area should go down with an increase in average thickness and no change in volume. This would of course result in an albedo decline and and increase in the melting rate. This would of course be balanced against the direct effects of the snow and cooler and cloudier weather caused by the storm itself.

Rob Dekker

Bill Fothergill said

It looks as though someone at NSIDC has done a bit of cut&paste without checking if the paragraph still makes sense. ... I would hazard a guess that, from Jan 2008 onwards, the offset value reduces to 0.029 - but it could certainly have been phrased better.

Does that help?

Yes, it does, and thank you for your reply.
I also noticed the difference between the notes in the old and the new files, and that the new 'area' numbers are adjusted upward (by indeed about 0.3) for 2008 onward.

So I think you are right that the new discontinuity is in 2008 only, and not in 2013. But I will contact the NSIDC helpdesk just to make sure.

Wipneus said :

Think of it: even if area equals extent every day of the month - 100% concentration within the ice extent, never any melt ponds or leads- grid cells that are only covered with ice during part of the month lead to an average concentration less than 100%.

I had to read that sentence a couple of times, but I understand what you mean. And yes, this may be a problem for even my simple model, and it may explain differences between the NSIDC's area numbers and other data sets.

Let me think about this a bit and then I will try to come up with a better method for determining "extent minus area" as a metric to determine leads and melting ponds.

Thanks !

Wipneus

Rob, I was tired glad you could figure it out.

Make sure that you did see my compactness graph at
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-compact-compare.png

Three different sea ice concentration datasets, computed by very different methods (not to mention the two different satellite sensors) all agree that the compactness in May (and currently) is unusually high.

Daily data for NSIDC is here:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_nt_nrt_main.txt
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data/nsidc_nt_final_main.txt.gz

Data for the Jaxa L3 SIC is here:
https://sites.google.com/site/arctischepinguin/home/amsr2/data/Jaxa_AMSR2_L3_10km_Area_Extent-v0.0.txt

Data for the Uni Hamburg 3.125km AMSR2 SIC is here:
https://sites.google.com/site/arctischepinguin/home/amsr2/data/UH_AMSR2_3.125km_Area_Extent-v0.0.txt

Neven

Our friend has bottomed out at 970 hPa:

navegante

D, the persistent cyclone, as far as I remember, was weak and . . . persistent :) Came from Siberia like a thief in the night and stood for weeks ocuppying the Arctic. This one is more like SWAT from Northern Europe breaking into the house, so to speak :) Still we will see if the SWAT calm down and decide to stay for a coffee or two

navegante

Although the truth is, the forecast for Beaufort and especially Chukchi for the next five days or so does not look very conductive for melting. Lows, lack of insolation . . . the momentum there may be lost or delayed, the clock is ticking and sun is needed.
A great steady warm flow toward Fram may be developing though.

RunInCircles

Help me understand. One of the features of Cyrosphere today is their view of snow cover. I have never seen this much snow cover left in June. Other comments indicate snow cover is low in the northern hemisphere but this is not even close to what I am seeing on their map? Can somebody explain please?

Chris Reynolds

Thanks Rob, glad to see it was a useful perspective.

Kevin O'Neill

RunOnCircles:Look near the top of the Cryosphere Today Homepage on the lefthand side, above the global maps and below the charts; you'll find this note:

"Note: snow cover data not updating ... we hope to have a new data source by July, 2015."

RunInCircles

Thanks Kevin

Werther

Whatever ‘meltpond-june’ may or may not bring, the recent large Low has had an effect on ice distribution in the CAB.

 photo Polar detail 10062015 smallest_zpsmknvzird.jpg

This 500 km radius circle around the pole is from today’s MODIS, enhanced picture (bright -10/contrast +22/mid-tones -64).

It shows a lot of torn leads and open water, as the surface winds have dispersed while compacting elsewhere. It looks like the large swath of thinner ice in the ‘Laptev-bite-to-come’ has been messed up most.
I’ll post a larger version on the Forum.

Neven

Thanks for that, Werther. Awesome.

Things have slowed down in the Arctic right now, but the second round is about to begin.

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