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Author Topic: Short to Medium Term Arctic Sea Ice Conditions Discussion  (Read 593099 times)

jdallen

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #900 on: July 19, 2013, 08:54:35 AM »
I will however make an additional observation that goes back to my thinking that the extent is giving us an illusion of comfort, when it is really hiding problems.

If you look at the two images, at the area immediately to the east of the Chukchi on the Siberian side, it would appear that the 2013 ice is in much better shape than the same area in 2012.

Here's an image of the region from Lance-Modis from a few days ago, the most recent I could find with a good image of the area.

http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r05c04.2013196.terra.250m

*That* is not pack ice.  *That* is <b>Mush</b>, covering a significant fraction of the area which 2012, was reported as more or less 60-70% concentration.

Let's compare:

http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r05c04.2012196.terra.250m

I'm not really seeing 2013 being in better shape.  In fact, I believe I'm seeing much less in the way of larger, intact floes, and more in the way of grey slush.  It covers *somewhat* more surface, but I'm having a hard time believing it is more coherent/resistant to melt than the area in 2012.

We could compare other areas, and some may appear in fact to be more solid; perhaps they are. However over all, I still think the quality of the ice will prove lethal to the pack.  The next 10 days should tell us.  If 2013 catches up, I think that will indicate the ice quality is a serious factor, and it will be a good bet that we'll see extent and area crash past 2012.

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Frivolousz21

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #901 on: July 19, 2013, 09:42:12 AM »


the Atlantic side is in awful shape.  We are close to seeing it melt out.  Hycom was right that this event happened.  Now the ice is close to it's death there.  It's amazing.

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werther

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #902 on: July 19, 2013, 10:31:54 AM »
I'm probably laying my eggs in the same nest as Friv and JDAllen did above...
Haven't done much yesterday, except going over the MODIS tiles and ECMWF.
I'd rather like to report on some actual hard work done with the help of CAD and being specific on a clear cut region than debiting generalities.
So why not shut up, wait and see?
OK, but quickly... this ice isn't going to shape up until the last week of August, when insolation really gets smaller and temps start falling. Until then, no stretch of days can give a conclusion like "...if within 10, than not..." or that sort of general assumptions. With the right trigger, flash melt can happen any time until the end of August.
And flash could mean 3Mkm2 in a week ( now I'm really stretching my credibility, I know... Shizuku will pick up some rubble over 15% anyhow I guess).)

Wipneus

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #903 on: July 19, 2013, 10:57:48 AM »

OK, but quickly... this ice isn't going to shape up until the last week of August, when insolation really gets smaller and temps start falling. Until then, no stretch of days can give a conclusion like "...if within 10, than not..." or that sort of general assumptions. With the right trigger, flash melt can happen any time until the end of August.

Indeed Werther. I think flash melting was introduced describing the effects of a Not-So-Great Arctic Cyclone at the end of August 2011:

http://neven1.typepad.com/blog/2011/08/flash-melting.html

werther

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #904 on: July 19, 2013, 11:04:26 AM »
While discussing all of this, IJIS has updated.
Illustrating the possibilities with a massive -197K drop...
In striking distance now with all three contenders ('07, '11, '12). Two more like this and " quod erat demonstrandum ".
« Last Edit: July 19, 2013, 11:19:46 AM by werther »

werther

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #905 on: July 19, 2013, 11:56:26 AM »
Just saw this on ECMWF:


Friday 1907 + 120 h…

Still 4 days out, but if it pans out…

While circlin’ in through the ESAS and on the edge of the CAB it gets strenghtened by another low from the Norwegian Sea. ECMWF entitles it lots of energy…

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #906 on: July 19, 2013, 01:02:44 PM »
And... what can you say... did you see CT coming in?

BornFromTheVoid

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #907 on: July 19, 2013, 03:08:28 PM »
Both the ECM and GFS in good agreement on the storm net week.

GFS


ECM


New NASA Model


Good thunderstorm potential in Ireland, and an Arctic storm to keep me occupied next week. Exciting times.

kynde

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #908 on: July 19, 2013, 05:47:31 PM »
The GAC2013?

Very exciting heads up, thanks guys.

Shared Humanity

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #909 on: July 19, 2013, 05:47:52 PM »
With a low over the Beaufort and a possible high over Greenland, could these work together to push a lot of ice out the Fram?

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #910 on: July 19, 2013, 06:25:37 PM »
With a low over the Beaufort and a possible high over Greenland, could these work together to push a lot of ice out the Fram?

Not in the near term.



But it is going to spread out the eastern CAB, and possibly accelerate the crumbling.

Vergent
« Last Edit: July 19, 2013, 06:41:20 PM by Vergent »

Laurent

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #911 on: July 19, 2013, 06:31:37 PM »
It seems there will be a lot of rain over Beaufort very soon !
http://www.weather-forecast.com/maps/Arctic?symbols=none&type=prec

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #912 on: July 19, 2013, 06:33:20 PM »
This low is forecast to be about 995mb central pressure, last years August Storm was below 985mb.

Furthermore, using SSMIS (Bremen AMSR-2 doesn't start until 24 July 2012):

<snippage>

Same time last year the ice was in a worse state over the Pacific sector.
Chris;

Please excuse if that came across as wild-eyed doomsaying.  I was not trying to suggest the impending doom of the ice by way of a repeat of 2012.  That said, 995 is a pretty low pressure, and should kick up some fairly good circulation.   My observations was more musing over what a reasonable cyclone would do to the ice in the Beaufort (and elsewhere, for that matter) in its current state.

No need to plead excuse, it's a reasonable speculation given the impact of last year's storm.

995 really isn't that low, but unless I missed something last night the forecast has updated. The storm is now projected to bottom out at 980mb on Tue 23 July, GFS. HYCOM doesn't show a similar impact to the Laptev Bite, but this storm is of shorter duration.
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

However HYCOM didn't do well with the 2012 storm.

Bremen shows a substantial loss from 1 Aug to 7 Aug.
1 Aug 2012.
http://www.iup.uni-bremen.de:8084/amsr2data/asi_daygrid_swath/n6250/2012/aug/asi-AMSR2-n6250-20120801-v5_visual.png
7 Aug 2012.
http://www.iup.uni-bremen.de:8084/amsr2data/asi_daygrid_swath/n6250/2012/aug/asi-AMSR2-n6250-20120807-v5_visual.png

But HYCOM prediction on 2 Aug doesn't predict such a massive loss.
2 Aug 2012
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn/nowcast/ictn2012080118_2012080200_035_arcticictn.001.gif
7 Aug 2012.
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn/nowcast/ictn2012080118_2012080700_035_arcticictn.001.gif

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #913 on: July 19, 2013, 06:46:20 PM »
The ice movement plot Vergent just posted reveals a problem with the HYCOM forecast. Ice movement doesn't seem to be reflecting the storm in GFS and ECM. As stated on their site:

Atmospheric forcing in ACNFS is obtained from the Fleet Numerical Meteorology and Oceanography Center 3 hrly 0.5° Naval Operational Global Atmospheric Prediction System (NOGAPS) (Hogan et al., 1991) forcing.

NOGAPS seems to have the storm over towards the Siberian side. Which may explain the predicted ice movement there. FWIW I'd back GFS and ECM, especially as BFTV shows those models agree.


After the years post 2007 being cool wet summers here in the UK, we've had a blocking high for weeks, and now the ground is dry the temperatures are shooting up. Manchester Airport now 29degC, where I live is 30.1, an infra-red thermometer gives the road surface temperature outside my house as 46degC. Having been in a temperature/humidity controlled lab (20degC +/-1degC) all day, this heat is stunning.

BornFromTheVoid

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #914 on: July 19, 2013, 07:03:19 PM »
Similar situation in Ireland Chris, the grass is dying quite quickly now. 29C today in many parts of Ireland yet again. There should be some relief next week though.


Anywho, the storm is still there of the 12z GFS run


jdallen

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #915 on: July 19, 2013, 07:18:38 PM »
OK, but quickly... this ice isn't going to shape up until the last week of August, when insolation really gets smaller and temps start falling. Until then, no stretch of days can give a conclusion like "...if within 10, than not..." or that sort of general assumptions. With the right trigger, flash melt can happen any time until the end of August.
And flash could mean 3Mkm2 in a week ( now I'm really stretching my credibility, I know... Shizuku will pick up some rubble over 15% anyhow I guess).)

<insert chuckle here> Perhaps as is appropriate with the 'new' arctic, my assertion should have read,
'The next ten days will narrow the range of probability...'

  ;)
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Chuck Yokota

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #916 on: July 20, 2013, 01:29:12 PM »
There has been a remarkably clear view in the last few days of the collapse of the ice in the Parry Channel between Devon, Somerset, and Cornwallis Islands.

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #917 on: July 20, 2013, 07:29:57 PM »
BFTV,

Looks like we remain in a blocking high regime though, although perhaps on the periphery*, I suspect we won't see serious low pressures until later in August.

Updated forecasts now suggests a breakdown into a mildly low pressure regime.
« Last Edit: July 21, 2013, 05:42:35 PM by ChrisReynolds »

jdallen

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #918 on: July 20, 2013, 07:54:37 PM »
BFTV,

Looks like we remain in a blocking high regime though, although perhaps on the periphery, I suspect we won't see serious low pressures until later in August.

980 forecast on 7/24 over the Beaufort?  Or are you talking about the margins of the basin, rather than the ice proper?
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Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #919 on: July 20, 2013, 08:10:32 PM »
Big high over Greenland - 1030 hPa - as well:

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jdallen

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #920 on: July 20, 2013, 11:04:05 PM »
Big high over Greenland - 1030 hPa - as well:

... Which combined with the 980hPa low, makes for a rather high gradient. That's a 5% difference in pressure, and a huge amount of potential energy.  Expect requisite high wind velocities.   
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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #921 on: July 21, 2013, 12:49:02 AM »
... Which combined with the 980hPa low, makes for a rather high gradient. That's a 5% difference in pressure, and a huge amount of potential energy.  Expect requisite high wind velocities.
Hi jd,

It's 2,500 km between those two centers of pressure. Here's how to calculate the gradient wind:

http://mysite.du.edu/~etuttle/weather/wind.htm#Grad
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jdallen

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #922 on: July 21, 2013, 03:56:59 AM »
... Which combined with the 980hPa low, makes for a rather high gradient. That's a 5% difference in pressure, and a huge amount of potential energy.  Expect requisite high wind velocities.
Hi jd,

It's 2,500 km between those two centers of pressure. Here's how to calculate the gradient wind:

http://mysite.du.edu/~etuttle/weather/wind.htm#Grad

Outstanding!  Thanks, Dodger.
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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #923 on: July 21, 2013, 04:19:42 AM »
I think flash melting was introduced describing the effects of a Not-So-Great Arctic Cyclone at the end of August 2011
Hi Wipneus,

My recollection is that we first started using the term 'flash-melting' to describe what happens when a large region of sea ice at 20-odd % concentration all goes below the 15% SIE threshold over a single day.

Previously, the best way to detect that type of situation is to compare it to a data reporting source using a 30% threshold.

Now, YOU are the best way! (with your AMSR2 data)  8)
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AartBluestoke

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #924 on: July 21, 2013, 06:27:25 AM »
.. the term 'flash-melting' to describe what happens when a large region of sea ice at 20-odd % concentration all goes below the 15% SIE threshold over a single day.

And this is the problem with using any specific threshold -- you can get a nice uniform linear loss of 5%/week from top/bottom melting, then on some specific day you cross a threshold and it looks like "lots" of melt happens on that specific day.

Would it be possible to create a set of graphs with extent vs time, with plots of extent with a threshold of 5,10,15,25,33,50,75,90,95% ?

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #925 on: July 21, 2013, 07:04:30 AM »
Wipneus could do the concentration distribution curve, but we only have 1 year of data.
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ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #926 on: July 21, 2013, 08:26:30 AM »
BFTV,

Looks like we remain in a blocking high regime though, although perhaps on the periphery, I suspect we won't see serious low pressures until later in August.

980 forecast on 7/24 over the Beaufort?  Or are you talking about the margins of the basin, rather than the ice proper?

Sorry, we're talking about UK and Ireland.

jdallen

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #927 on: July 21, 2013, 09:48:23 AM »
BFTV,

Looks like we remain in a blocking high regime though, although perhaps on the periphery, I suspect we won't see serious low pressures until later in August.

980 forecast on 7/24 over the Beaufort?  Or are you talking about the margins of the basin, rather than the ice proper?

Sorry, we're talking about UK and Ireland.

Ah! Makes perfect sense now. I haven't checked specifics, but much the same is taking place across the inter montane west.
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ktonine

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #928 on: July 21, 2013, 01:36:43 PM »
HYCOM is showing some significant changes in the next week:


ktonine

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #929 on: July 21, 2013, 01:48:49 PM »
Here's the single frame for 7-27



Looks like a lot if ice is going to be thrown back into the open coastal waters in the Chukchi and Beaufort.

I can't determine what the net effect will be on the low concentration areas near the pole.

Overall it looks like extent should increase - but with ice being thrown back into (warmer) open waters, area and volume should take sizeable hits.

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #930 on: July 21, 2013, 03:10:46 PM »
Ah! Makes perfect sense now. I haven't checked specifics, but much the same is taking place across the inter montane west.

It may seem off topic, but the UK has had cool wet summers since 2007, associated with a new pattern of atmospheric circulation. And since 2007 sea ice levels have been low. This year is highly unusual because the pattern hasn't developed. Anyway it's cooler today, and there's the chance of thunderstorms over the next few days. We rarely get thunderstorms, and I love them, my fingers are crossed for some exciting storms.  ;D

Apocalypse4Real

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #931 on: July 21, 2013, 05:03:02 PM »
@Chris, UK then had a recent heat wave - longest stretch of high temps in years that threatens wheat production.

"Temperatures in the U.K. have climbed above 82 degrees Fahrenheit for 11 days, the longest hot spell since 2006, the Met Office said today in an online report. England had 0.2" of rain on average in the first two weeks of July. Similar precipitation totals in the second half of the month would mean the driest July for the region since 1825, when England and Wales saw just 0.3" of rain, the national weather forecaster said."

http://www.agweb.com/article/wheat_threat_looms_as_uk_heat_wave_rivals_2006_BLMG/

Now back to the coming GAC 2013 (1) (the (1) reflects my expectation that we will see more than one GAC this year - time will tell.)

The Ohio State University Polar forecast for 25  July 2013 at 0000 UTC calls for a 976 mb SLP low to park over the CAB. The coastal temps in Siberia and Alaska and the CAA are high.

Link:
http://polarmet.osu.edu/nwp/animation.php?model=arctic_wrf&run=00&var=plot001

See attached: for 250713 0000

While fairly strong, I think its persistence will be a telling factor on ice impact.

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #932 on: July 21, 2013, 05:15:22 PM »
A4R,

...the longest hot spell since 2006...

Residuals from the trend in Central England Temperature series show the cooling post 2006, taken from a 2011 blog post, so only going up to 2011. Note the post 2007 drop.

I'll update that when CET figures are in for this summer, so far I expect an uptick.

Apocalypse4Real

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #933 on: July 21, 2013, 05:39:00 PM »
Thanks Chris,

My sister-in-law has been sweating it out in Watford! Of course tomorrow's 32 C in her area will not be enjoyed. She is ready for cooler temps.

Enjoy the thunderstorms! If you lived in Florida, you'd get them about every day this time of year. Picture: Clearwater Beach Florida, 2012.

I'll stay on topic after this - back to the ice.

A4R

Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #934 on: July 21, 2013, 06:40:05 PM »
I have just published Arctic Sea Ice 2013 update 5: cyclone time again.

Excerpt:



Now that's a big cyclone, very, very similar to last year's Great Arctic Cyclone. Except that it comes out of nowhere, and quickly de-intensifies after Wednesday. It will do some damage to the ice pack, but not as much as last year. Note also the high-pressure area over Greenland.

Of course, the forecast can change.
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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #935 on: July 21, 2013, 07:13:04 PM »
Hello everybody .. this is my first post on this site and am thankful to BornFromTheVoid for recommending checking you out
 There has never been a more interesting time in man's experiment with his home. And never has so much information been so readily available on the weather and climate of our planet.
I realize I have missed the Arctic Area minimum predictions  but see I would have been in the lowest 10% of forecasts .. for the same reasons as the forecast of Arctic ice movement(5 posts} above is blood red .. permanent sea ice has been replaced with seasonal pack ice ,and after tomorrow's full moon will be at the whim of tide and wind
  The forming GAC? may be there for some time .. both GEM Canada and JMA still have it as a deep central Arctic feature at the end of their current 10 and 7 day runs .
  Is an ice free Arctic and it's consequences the prerequisite of any serious reversal of the insanity of humanity ?

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #936 on: July 22, 2013, 05:03:09 PM »
A glimpse between the clouds of the sea ice at the North Pole today, from Terra via Worldview:
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Apocalypse4Real

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #937 on: July 23, 2013, 04:36:18 AM »
Great catch Jim,

It seems to show us that most of the Arctic has the consistency of a Slurpee in the US. If this stirred and shaken then a good dose of sunlight, we may see a closing in on prior years melt.

ktonine

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #938 on: July 23, 2013, 04:41:08 AM »
Cross posted with ASIB:

As we contemplate the possible effects of the predicted cyclone, we have this from Matthew Asplin (PhD Graduand). He has published with Dr. Dave Barber and submitted Cyclone Forcing of the Ocean-Sea Ice-Atmosphere Interface  as his PhD thesis.

" I think there is enough open water, and enough fracturing in the sea ice surface, as well as weakening (preconditioning), that mechanical forcing from this storm's winds, storm surge, waves, and possible local upwelling and mixing of the near-surface ocean layer could drive a rapid reduction in extent, as we saw last year. Cloud cover from this storm will temper the solar insolation. Given that this is occuring in late July, we still have all of August, and half of September for further solar-driven melting, or storm-forcing.

This is definitely an event to watch, and definitely the "Year of the Arctic Cyclone" when it comes to predicting the Arctic sea ice minimum extent.
"


(And thanks to Matthew for allowing me to add his comments to our discussion.)

BornFromTheVoid

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #939 on: July 23, 2013, 12:58:27 PM »
Hello everybody .. this is my first post on this site and am thankful to BornFromTheVoid for recommending checking you out
 There has never been a more interesting time in man's experiment with his home. And never has so much information been so readily available on the weather and climate of our planet.
I realize I have missed the Arctic Area minimum predictions  but see I would have been in the lowest 10% of forecasts .. for the same reasons as the forecast of Arctic ice movement(5 posts} above is blood red .. permanent sea ice has been replaced with seasonal pack ice ,and after tomorrow's full moon will be at the whim of tide and wind
  The forming GAC? may be there for some time .. both GEM Canada and JMA still have it as a deep central Arctic feature at the end of their current 10 and 7 day runs .
  Is an ice free Arctic and it's consequences the prerequisite of any serious reversal of the insanity of humanity ?

                 be cause

Welcome along be cause!

Looks like the ECM is making the storm a 48-72 hour event.

t24


t48


t72


It will be interesting to see what effects it has, given that the ice is in slightly better condition and the storm ain't quite as strong as last August

wili

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #940 on: July 23, 2013, 01:24:26 PM »
" the ice is in slightly better condition"

I assume you mean by area and extent numbers.

It seems to me that, if this brief cyclone does do significant damage to the ice pack, it will tell us precisely that the ice this year been has actually in worse condition, even though the numbers look better.

Interesting indeed.
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BornFromTheVoid

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #941 on: July 23, 2013, 01:41:51 PM »
" the ice is in slightly better condition"

I assume you mean by area and extent numbers.

It seems to me that, if this brief cyclone does do significant damage to the ice pack, it will tell us precisely that the ice this year been has actually in worse condition, even though the numbers look better.

Interesting indeed.

Nope, I mean looking at the MODIS imagery. The ice over the Beaufort, Chukchi and western central Arctic (main areas to be affected) look in better condition as this storm approaches than Chukchi, ESS and the Pacific side of the central Arctic looked with the approach of GAC12.

Given that the storm is also much weaker, I wouldn't expect the same dramatic results as last August (that storm had a central pressure <970hPa and a much larger damaging wind field)

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #942 on: July 23, 2013, 07:00:14 PM »
" the ice is in slightly better condition"

I assume you mean by area and extent numbers.

It seems to me that, if this brief cyclone does do significant damage to the ice pack, it will tell us precisely that the ice this year been has actually in worse condition, even though the numbers look better.

Interesting indeed.

Nope, I mean looking at the MODIS imagery. The ice over the Beaufort, Chukchi and western central Arctic (main areas to be affected) look in better condition as this storm approaches than Chukchi, ESS and the Pacific side of the central Arctic looked with the approach of GAC12.

Given that the storm is also much weaker, I wouldn't expect the same dramatic results as last August (that storm had a central pressure <970hPa and a much larger damaging wind field)

Agreed.

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #943 on: July 23, 2013, 07:13:55 PM »
The ice pack as a whole might look better, as there is more of it, and it is a lot less patchy than last year. The ice itself looks just as bad, in my opinion, with huge regions of grey mush with a couple of individual floes in it.

I would be surprised if we'd see no effect at all. ECMWF now has at least two days of pretty stormy conditions.
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Peter Ellis

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #944 on: July 23, 2013, 09:58:42 PM »
You see "huge regions of grey mush with a couple of individual floes in it".  I see "contiguous pack that hasn't been shattered into individual floes", which is a plus so far as I'm aware.  Yes, it's quite grey, which indicates quite thin ice with ponds and/or drained ponds - but thus far it's maintaining its integrity surprisingly well.

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #945 on: July 23, 2013, 10:03:29 PM »
You're definitely right about the surprising part. This ice was supposed to be thinner than last year's. Maybe it has to do with the amount of heat released during the fragmentation event?

Sorry that I keep saying the same things.  ;D
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Peter Ellis

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #946 on: July 23, 2013, 10:13:36 PM »
From the Canadian Ice Service contribution to the June SEARCH outlook:
http://www.arcus.org/files/search/sea-ice-outlook/2013/06/pdf/pan-arctic/canadianiceservice.pdf

"Air temperatures in the southeastern Beaufort Sea were well below both the 1971‐2000 and 1981‐2010 normals this past winter, especially in February. These cold temperatures, combined with the southward compaction of the sea ice due to the negative‐AO‐enhanced Beaufort Gyre, caused the sea ice in this area to become almost immobile for an extended period. When movement in the ice pack resumed, the sudden re‐fracturing of the Beaufort ice at the end of February / early March was catastrophic and made news headline everywhere. Following this fracture event, limited movement and colder than normal air temperatures in the southern Beaufort Sea then resumed. The onset of melt in the southern Beaufort Sea is therefore expected to be “near‐normal” this year, as opposed to “earlier than normal”.

Going by that, one reason the cracking in March appeared so dramatic is that the first-year ice was actually thicker and tougher than usual due to a colder than average winter, meaning the (normal) circulation and spread was concentrated into fewer, wider cracks.  They're the ones nearest on the ground, so they're better placed than any of us to know what's going on.

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #947 on: July 23, 2013, 10:42:26 PM »
GAC-2012 A is developing two weeks earlier than its predecessor, GAC-2012 last year.

The pattern is much the same. A strong jet-stream branch out of Kolyma-Siberia spins a lot of energy in on the 500-300Mb level, creating an all-troposphere cyclonic feature. Sounds nice…

From Squall Jet Stream CRWS: 6 August 2012


After this jet sweep, GAC 2012 lasted until 9 August.

For a grasp on what this coming storm could perform, I’d give most attention to the atmospheric circulation. There’s strong ridging all around the Arctic Basin, enough  energy is being provided. There’s more moisture in the atmosphere too.

From ECMWF:


OTOH, lower tropospheric temperature differences don’t look too supportive. Also, less open water is available for the storm to pick up extra moisture and spur from the ice-water boundary.

Again from ECMWF Tuesday 12:00 h:


Later today, the forecast weakened for Saturday.

I think this storm is exemplary for the ones we will see in the near future. As it is quite early, there’s good chance for another.

Meanwhile, the process of weakening the ice continues. After all, these storms are the pinch-hitters. The damage will accrue, no matter what form the weather takes…

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #948 on: July 23, 2013, 10:50:57 PM »
Peter,
I don’t doubt the Beaufort analysis. But for the sake of proportion, I reintroduce this temp summary for the refreeze season until 14 February:



You see, it was ‘normal’ in the outer nook of the Beaufort, just against the Amundsen Gulf, in line with the climo. Any of us can check NCEP/NCAR for the rest of the season.

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #949 on: July 23, 2013, 11:29:41 PM »

Going by that, one reason the cracking in March appeared so dramatic is that the first-year ice was actually thicker and tougher than usual due to a colder than average winter, meaning the (normal) circulation and spread was concentrated into fewer, wider cracks.  They're the ones nearest on the ground, so they're better placed than any of us to know what's going on.

Could be, but the SEARCH report (regional outlook) also has this:

"Kaleschke and Rickert provided an estimate of the difference between March 2013 and March 2012 ice thickness based on preliminary data from the European Space Agency’s satellites CryoSat-2 and SMOS (Figure 6). An increase in ice thickness in the Laptev, Kara, and Barents Seas was highlighted in their report."

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