Please support this Forum and Neven's Blog

Author Topic: Greenland 2017 melt season  (Read 13294 times)

lurkalot

  • ASIF Lurker
  • Posts: 11
    • View Profile
Re: Greenland 2017 melt season
« Reply #50 on: July 20, 2017, 08:35:35 PM »
Ever heard of Sod's Law, Gerontocrat? A few minutes after your post, NSIDC revealed one of the biggest melt days on record.

BlackPhillip

  • ASIF Lurker
  • Posts: 1
    • View Profile
Re: Greenland 2017 melt season
« Reply #51 on: July 20, 2017, 08:50:52 PM »
Ever heard of Sod's Law, Gerontocrat? A few minutes after your post, NSIDC revealed one of the biggest melt days on record.


Is it raining or is it snowing?

DMI and NSIDC seem to disagree.

DMI has decent melting for 7/19, but any mass loss for that date is completely overwhelmed by significant snow on the interior of southern Greenland. On the whole it looks like Greenland very slightly gained mass on that date.



NSIDC shows a significant portion of southern Greenland (including interior) as melting, which has led to a very high (extraordinarily high if you consider how this season is going) melt %.



Does anyone know what is actually happening?

Juan C. García

  • ASIF Citizen
  • Posts: 442
    • View Profile
Re: Greenland 2017 melt season
« Reply #52 on: July 20, 2017, 10:16:58 PM »
« Last Edit: July 20, 2017, 10:26:49 PM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

oren

  • ASIF Upper Class
  • Posts: 1487
    • View Profile
Re: Greenland 2017 melt season
« Reply #53 on: July 20, 2017, 10:20:01 PM »
 Holy s**t!

Neven

  • Administrator
  • ASIF Governor
  • *****
  • Posts: 3961
    • View Profile
    • Arctic Sea Ice Blog
Re: Greenland 2017 melt season
« Reply #54 on: July 20, 2017, 10:26:49 PM »
Maybe the difference has to do with DMI being about surface mass, while NSIDC is about surface melt? Or maybe one interpreted precipitation as rain and the other as snow. I have no idea, I don't follow Greenland melt all that much. But there could be another spike, as the forecast is for warm, sunny weather over much of Greenland in days to come.
Il faut cultiver notre jardin

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #55 on: July 21, 2017, 02:12:10 PM »
Maybe the difference has to do with DMI being about surface mass, while NSIDC is about surface melt? Or maybe one interpreted precipitation as rain and the other as snow.

DMI is about both melt (mass loss obviously mainly on the periphery) and mass gain - snow fall. You need the complete set of three images to get it all. DMI and NSIDC's analysis are in agreement, but DMI is adding back snowfall to get the surface mass budget.

It is of note (at least to me) that a high melt percentage (actually, not that high) can be offset totally by some snowfall. It is also getting late in the melting season. The end result for the surface mass balance is going to be unusual.
« Last Edit: July 21, 2017, 02:58:45 PM by gerontocrat »

Adam Ash

  • ASIF Citizen
  • Posts: 223
    • View Profile
    • The 100 metre line
Re: Greenland 2017 melt season
« Reply #56 on: July 21, 2017, 02:44:37 PM »
I guess the one thing the SMB may not account for is the melt of the underside of glaciers?  Presumably the lowering of the top ice surface to ballance the bottom melt is noted in the overall mass  ballance.

nukefix

  • ASIF Citizen
  • Posts: 393
    • View Profile
Re: Greenland 2017 melt season
« Reply #57 on: July 22, 2017, 12:04:58 PM »
The Greenland surface melt products are sensitive to the presence of small amounts of liquid water (wet snow) on the surface. The SMB can still be positive when surface melt (=wet snow) is detected on the ice sheet.

oren

  • ASIF Upper Class
  • Posts: 1487
    • View Profile
Re: Greenland 2017 melt season
« Reply #58 on: July 22, 2017, 01:24:00 PM »
I don't see a contradiction. Isn't rain included in the SMB as well? As long as it doesn't run off the ice sheet, and I'm sure a lot of it doesn't,  it adds to surface mass, and registers as surface melt as well.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #59 on: July 22, 2017, 01:59:39 PM »
Ever heard of Sod's Law, Gerontocrat? A few minutes after your post, NSIDC revealed one of the biggest melt days on record.

OK, lurkalot, so the dog has managed a "whoof" or two. But a whoof, (first graph: melt-combine) does not change the story for the year (2nd graph : accumulated smb). The dog has to bark a lot louder and longer to change the story's plot.
Whereupon, looking at cci-reanalyzer, it seems the dog is raising its volume somehwat now and for the next few days

To me there is a serious question as to whether this year is a one-off or a climatic change, especially as elsewhere there has been much discussion about unusually high snowfall all around the Arctic Ocean (and maybe on the ocean) last fall, winter and spring.
« Last Edit: July 22, 2017, 02:10:53 PM by gerontocrat »

Coffee Drinker

  • ASIF Lurker
  • Posts: 23
    • View Profile
Re: Greenland 2017 melt season
« Reply #60 on: July 23, 2017, 04:14:51 AM »
The average height of the ice sheet is something like 2000m. How often does it actually rain at that altitude during the Greenland summer?

My gut feeling tells me that the Greenland ice sheet is predominately driven by precipitation and not so much by actual temperature.

TerryM

  • ASIF Upper Class
  • Posts: 1860
    • View Profile
Re: Greenland 2017 melt season
« Reply #61 on: July 23, 2017, 01:05:45 PM »
The average height of the ice sheet is something like 2000m. How often does it actually rain at that altitude during the Greenland summer?

My gut feeling tells me that the Greenland ice sheet is predominately driven by precipitation and not so much by actual temperature.
How do you explain 2012?
Terry

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #62 on: July 23, 2017, 04:42:06 PM »
The average height of the ice sheet is something like 2000m. How often does it actually rain at that altitude during the Greenland summer?

My gut feeling tells me that the Greenland ice sheet is predominately driven by precipitation and not so much by actual temperature.
How do you explain 2012?
Terry
I guess that sometimes in summer a plume of warm air comes up and bingo, rain at high altitude. In 2012 it happened a lot, this year not often at all. 2012 was unique. One presumes that as AGW continues, the snowline will creep up the mountainsides.

Darvince

  • ASIF Citizen
  • Posts: 197
    • View Profile
    • NSIDC Daily
Re: Greenland 2017 melt season
« Reply #63 on: July 23, 2017, 04:44:54 PM »
This is a quick-and-dirty mathematical idealization of the ice thickness of the GIS as you get further into the interior (it's just cube root(x) shifted leftwards):



As you can see, the amount of area of Greenland melting increases faster and faster as the airmasses above Greenland warm, due to its gentler slope in the interior. Therefore the melting percentage on any individual day is more likely to be between 20-30% than between 60-100%, despite the much greater range of the second value set.

charles_oil

  • ASIF Citizen
  • Posts: 178
    • View Profile
Re: Greenland 2017 melt season
« Reply #64 on: July 24, 2017, 10:57:13 PM »

Good short BBC article on BBC News channel today about visiting Greenland and monitoring the darkening ice.
http://www.bbc.com/news/science-environment-40686984

crandles

  • ASIF Upper Class
  • Posts: 1724
    • View Profile
Re: Greenland 2017 melt season
« Reply #65 on: July 24, 2017, 11:20:47 PM »

Good short BBC article on BBC News channel today about visiting Greenland and monitoring the darkening ice.
http://www.bbc.com/news/science-environment-40686984


Also mentions this:
http://advances.sciencemag.org/content/3/6/e1700584
Satellite observations show that, from 1995 to 2009, summer cloud cover decreased by 0.9 ± 0.3% per year.


So about 12.5% less clouds over 14 years.
We are familiar with stronger greenland high pressure since 2007, but interesting to see cloud cover decrease numbers.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #66 on: July 25, 2017, 02:12:43 PM »
The dog has made a few muted "whoofs" over the last few days.  But loads of snow (rain?) in the southeast. The map "accumulatedmap" which shows the accumulated surface mass balance (in mm water equivalent) from September 1st 2016 to now illustrates the concentration of mass gain in that quarter.

There is a recent modest mass loss, and around 30% of Greenland has melt every day, but this is not above average. The threads on the glaciers have not talked about any spectacular calving events. Greenland ice sheet to have an overall mass gain this year?

Also the contrast of 2017 with 2012 is spectacular. It has always added to my conviction that 2017 was not going to see a massive sea ice melt.


nukefix

  • ASIF Citizen
  • Posts: 393
    • View Profile
Re: Greenland 2017 melt season
« Reply #67 on: July 25, 2017, 05:22:23 PM »
Also the contrast of 2017 with 2012 is spectacular. It has always added to my conviction that 2017 was not going to see a massive sea ice melt.
My thinking is that there's a limited amount of extra heat around - if Greenland is super-warm some other area is therefore cooler and sometimes this can conserve sea-ice. So let's see...

Daniel B.

  • ASIF Lurker
  • Posts: 52
    • View Profile
Re: Greenland 2017 melt season
« Reply #68 on: July 27, 2017, 06:30:19 PM »

So about 12.5% less clouds over 14 years.
We are familiar with stronger greenland high pressure since 2007, but interesting to see cloud cover decrease numbers.

Perhaps the increasing cloud cover this year has aided in the increasing ice mass.  There has certainly been more snowfall.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #69 on: July 28, 2017, 02:56:25 PM »
The dog has barked. The Greenland melting season has woken up with a vengeance. Not only has the melt area increased to 46% from 33% in two days, the intensity of the melt has increased, resulting in a doubling of daily surface mass loss from about 4 gigatonne to 8 gigatonne per day. This is a unique event this season.

cci-reanalyzer is also predicting continuing strong positive temperature anomalies for Greenland over the next 5 days.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #70 on: July 29, 2017, 04:19:35 PM »
http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/ says daily melt 28th July still up at 46% of area. Also for the first time this melt season the melt map below shows no surface mass gain anywhere on the ice sheet - clear skies. cci-reanalyzer shows these clear skies (and +ve temp anomalies) persisting for the next 5 days or so.

High daily surface mass loss seems set to continue.

Shared Humanity

  • ASIF Upper Class
  • Posts: 2020
    • View Profile
Re: Greenland 2017 melt season
« Reply #71 on: July 29, 2017, 07:17:23 PM »
That high is pulling a lot of warm moist air towards northwest Greenland.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #72 on: July 30, 2017, 03:22:45 PM »
That high is pulling a lot of warm moist air towards northwest Greenland.
Whereupon one immediately sees some snow / rain(?) dumped in NW Greenland - todaysmb graph below.

The melting remains intense (4 days so far) with up to 8 gigatonne (8 cubic kilometres) of cold fresh water being dumped per day into the ocean from the peripheral regions of Greenland. This is about twice the daily average for this time of year. This looks set to continue for a few days yet.

One wonders how much effect this has on the glaciers and for example, the sea ice attached north of Greenland and in the Nares strait.


oren

  • ASIF Upper Class
  • Posts: 1487
    • View Profile
Re: Greenland 2017 melt season
« Reply #73 on: July 30, 2017, 05:51:47 PM »
The melting remains intense (4 days so far) with up to 8 gigatonne (8 cubic kilometres) of cold fresh water being dumped per day into the ocean from the peripheral regions of Greenland. This is about twice the daily average for this time of year. This looks set to continue for a few days yet.

One wonders how much effect this has on the glaciers and for example, the sea ice attached north of Greenland and in the Nares strait.
The situation in Greenland is very interesting but I doubt that it affects the sea ice very much. Currents around Greenland generally flow to the south, and most of the melt area is in the southeast and southwest, so it seems this freshwater mainly goes to the "cold spot" in the Atlantic.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #74 on: August 03, 2017, 12:23:34 PM »
It seems that the recent strong melt is in decline. Of interest, to me at least, is that the 30 year average maximum for melt and surface mass loss was a few days ago, and surface mass gain starts by the end of August. I wonder if the Greenland melting season has extended in recent years.

magnamentis

  • ASIF Upper Class
  • Posts: 1199
    • View Profile
    • Nexpaq Modular ARA iOS Software Mobile Computing Phones Philosophy Ethics Numerology Mikrocirkulation Vaskular Therapie Gesundheit Blut Gesundheit Schmerzen Multipelsklerose Diabetes Immunsystem Fibromyalgie
Re: Greenland 2017 melt season
« Reply #75 on: August 03, 2017, 05:15:31 PM »
It seems that the recent strong melt is in decline. Of interest, to me at least, is that the 30 year average maximum for melt and surface mass loss was a few days ago, and surface mass gain starts by the end of August. I wonder if the Greenland melting season has extended in recent years.

well possible but the same was said one day before the last super-peak. even though your graphs are very useful i do not think they are suitable for daily usage when it comes to the value of the information they are providing. but that's only for efficiency-apostles like me ;) just keep going and do it your way, just a remark to consider.
http://magnamentis.com
Knowledge, Understanding & Insight Are Among The Best Sources For Personal Freedom & Vitality !

Daniel B.

  • ASIF Lurker
  • Posts: 52
    • View Profile
Re: Greenland 2017 melt season
« Reply #76 on: August 03, 2017, 06:32:31 PM »
It seems that the recent strong melt is in decline. Of interest, to me at least, is that the 30 year average maximum for melt and surface mass loss was a few days ago, and surface mass gain starts by the end of August. I wonder if the Greenland melting season has extended in recent years.

No, the season has not changed much over time.  Individual years fluctuate, depending on the specific weather patterns.  But overall, the maximum rate of melt occurs in July, with melting continuing until about the end of August (give or take a week or so). 

SCYetti

  • ASIF Lurker
  • Posts: 33
    • View Profile
Re: Greenland 2017 melt season
« Reply #77 on: August 04, 2017, 01:35:32 AM »
This may be a little off topic. But exactly what is burning in SW Greenland?

Csnavywx

  • ASIF Citizen
  • Posts: 404
    • View Profile
Re: Greenland 2017 melt season
« Reply #78 on: August 04, 2017, 01:42:21 AM »
The season will likely not extend until autumn ice pack vanishes and isolates the ice sheet as an airmass source.

TrevorH

  • ASIF Lurker
  • Posts: 2
    • View Profile
Re: Greenland 2017 melt season
« Reply #79 on: August 04, 2017, 04:00:56 AM »
This may be a little off topic. But exactly what is burning in SW Greenland?

Peat bog? Methane seep? Here's a Sentinel image from July 31 as it was just getting started.

Tor Bejnar

  • ASIF Upper Class
  • Posts: 1481
    • View Profile
Re: Greenland 2017 melt season
« Reply #80 on: August 04, 2017, 04:11:58 AM »
Here's a Sentinel Playground close up and region-wide view (with fire location near the center) 100 km inland of Attu (about 2/3s of the distance from coast to icesheet).
« Last Edit: August 04, 2017, 04:24:07 AM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

Tor Bejnar

  • ASIF Upper Class
  • Posts: 1481
    • View Profile
Re: Greenland 2017 melt season
« Reply #81 on: August 04, 2017, 04:44:21 AM »
Here are a couple of  picture from near Kangerlussuaq (according to internet search) which is about 100 km south of the fire that shows what I presume is typical vegetation: a shrubs and grasslands tundra. 

I looked at the location in previous years to see if this was a perennial fire (such as a coal seem fire) but it isn't.  Probably a 'grass fire', with nothing to put it out except rain or snow.


Arctic ice is healthy for children and other living things.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #82 on: August 04, 2017, 03:20:57 PM »

...even though your graphs are very useful i do not think they are suitable for daily usage when it comes to the value of the information they are providing. but that's only for efficiency-apostles like me ....

I just post what is happening in the current season.
The Greenland Ice Retreat thread is where one may discuss the long-term?

(One day I will understand Neven's perfectly understandable instructions on how to do links. Must be a mental block).

<Click 'modify' in the top right of this comment, and you can see how I changed your text to have the link appear within 'Greenland Ice Retreat thread; N.>

Meanwhile - the recent melting fades away. Greenland Net Mass Gain in 2017 for sure ?




« Last Edit: August 04, 2017, 05:10:35 PM by Neven »

Daniel B.

  • ASIF Lurker
  • Posts: 52
    • View Profile
Re: Greenland 2017 melt season
« Reply #83 on: August 04, 2017, 04:33:19 PM »

...even though your graphs are very useful i do not think they are suitable for daily usage when it comes to the value of the information they are providing. but that's only for efficiency-apostles like me ....

I just post what is happening in the current season.
The Greenland Ice Retreat thread is where one may discuss the long-term?
 -
 https://forum.arctic-sea-ice.net/index.php/topic,1120.msg123707.html#msg123707

(One day I will understand Neven's perfectly understandable instructions on how to do links. Must be a mental block).

Meanwhile - the recent melting fades away. Greenland Net Mass Gain in 2017 for sure ?

Seems like a given now.

nukefix

  • ASIF Citizen
  • Posts: 393
    • View Profile
Re: Greenland 2017 melt season
« Reply #84 on: August 04, 2017, 04:52:57 PM »
The fire looks great in S-2 SWIR-combination:

http://apps.sentinel-hub.com/sentinel-playground/?lat=67.84888987414084&lng=-51.514892578125&zoom=12&preset=91_SWIR&layers=B8A,B03,B02&maxcc=100&gain=1.0&gamma=1.0&time=2015-01-01|2017-08-03&cloudCorrection=none&atmFilter=&showDates=false&evalscript=

It could burn until the next rain I guess..

Reallybigbunny

  • ASIF Lurker
  • Posts: 29
    • View Profile
Re: Greenland 2017 melt season
« Reply #85 on: August 04, 2017, 10:06:50 PM »
Yes it does look great. Nice clear day. The fire is only around 3km diameter currently.

TerryM

  • ASIF Upper Class
  • Posts: 1860
    • View Profile
Re: Greenland 2017 melt season
« Reply #86 on: August 05, 2017, 06:01:30 AM »
This may be a little off topic. But exactly what is burning in SW Greenland?


Nice spotting!!
Thanks for your vigilance.
Terry

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #87 on: August 05, 2017, 02:05:15 PM »
Re Fires.

Ages ago I read an article about Greenland farming and the consequence of retreating ice on the periphery. It seems that the downside for existing farmland is that as the ice retreats the pastureland is drying out, less summer precipitation - don't ask me for the meteorological science that explains that.

Hence more chance of grass fires?

SCYetti

  • ASIF Lurker
  • Posts: 33
    • View Profile
Re: Greenland 2017 melt season
« Reply #88 on: August 06, 2017, 12:51:49 AM »
On NASA's Worldview 2 more fires appear today.


Tor Bejnar

  • ASIF Upper Class
  • Posts: 1481
    • View Profile
Re: Greenland 2017 melt season
« Reply #90 on: August 06, 2017, 06:02:11 AM »
I seriously doubt it.  A methane releasing might cause an explosion (as has been reported in Siberia), but a continuing fire would require a 'steady' release with ignition.  (Lightening might ignite it.)  A sustained burning gas release would need to be significant to be seen from a satellite.

The fires we see, I'm sure, are grass/brush tundra fires.
Arctic ice is healthy for children and other living things.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #91 on: August 06, 2017, 01:53:30 PM »
Greenland melting season starts its decline?

Shared Humanity

  • ASIF Upper Class
  • Posts: 2020
    • View Profile
Re: Greenland 2017 melt season
« Reply #92 on: August 06, 2017, 03:06:45 PM »
Greenland melting season starts its decline?

It's that time of year.

Tor Bejnar

  • ASIF Upper Class
  • Posts: 1481
    • View Profile
Re: Greenland 2017 melt season
« Reply #93 on: August 08, 2017, 08:14:21 PM »
Curious comment, Thomas.  I wouldn't have drawn that conclusion from the article. 
Yes, there was a trash fire in 2013.
Arctic ice is healthy for children and other living things.

johnm33

  • ASIF Middle Class
  • Posts: 746
    • View Profile
Re: Greenland 2017 melt season
« Reply #94 on: August 08, 2017, 08:24:00 PM »
"The fires we see, I'm sure, are grass/brush tundra fires" I'm not so sure it varies but there's some SO2 in the smoke. So perhaps an outcrop of lignite somewhere in the fire.
https://earth.nullschool.net/#2017/08/07/1200Z/chem/surface/level/overlay=so2smass/orthographic=-47.09,70.34,3000/loc=-51.389,67.768

Thomas Barlow

  • ASIF Citizen
  • Posts: 204
    • View Profile
Re: Greenland 2017 melt season
« Reply #95 on: August 09, 2017, 12:34:14 AM »
Curious comment, Thomas.  I wouldn't have drawn that conclusion from the article. 
Yes, there was a trash fire in 2013.
You are right, I misread it.

numerobis

  • ASIF Citizen
  • Posts: 195
    • View Profile
Re: Greenland 2017 melt season
« Reply #96 on: August 09, 2017, 07:42:34 PM »
This article blames peat:
http://www.nunatsiaqonline.ca/stories/article/65674tundra_fires_sweep_across_northwest_greenland/

Depending how deep the peat is, some of these fires could smoulder a long time.

crandles

  • ASIF Upper Class
  • Posts: 1724
    • View Profile
Re: Greenland 2017 melt season
« Reply #97 on: August 09, 2017, 07:51:24 PM »
also on the BBC
http://www.bbc.co.uk/news/science-environment-40877099
'Unusual' Greenland wildfires linked to peat

Peat fires worry researchers because the material stores large amounts of CO2 that is released through burning. They are also worried that the "black carbon" soot arising from the fires could land on the ice sheet and cause further melting.

Some rain is expected tomorrow which researchers hope will put the fire out.

gerontocrat

  • ASIF Middle Class
  • Posts: 518
    • View Profile
Re: Greenland 2017 melt season
« Reply #98 on: August 09, 2017, 09:59:44 PM »
From my time in Indonesia (of all places) I suggest that it takes a lot of rain to put out a peat fire. It gets well below the ground, and can smoulder for years without any obvious surface effects. Oxygen deprivation might do it - bring on the snow ?

Sailaway

  • ASIF Lurker
  • Posts: 3
    • View Profile
Re: Greenland 2017 melt season
« Reply #99 on: August 10, 2017, 02:42:16 AM »
Having seen peat fires in the Lincolnshire Fens burn for 3 years until they burn 14 ft down to the water table (lower than sea level due to drainage) I would be worried. The saving factor in Greenland may be a higher water content in the peat.

This book looks interesting https://books.google.com.au/books?id=OjL0CAAAQBAJ&pg=PA132&lpg=PA132&dq=fen+lands+burning+peat&source=bl&ots=Z9Y4PU71FQ&sig=LwO52o2HtwAO8TXwH3dFV7xYAEE&hl=en&sa=X&ved=0ahUKEwivnJyns8vVAhWJVLwKHUwuDpEQ6AEIVDAG#v=onepage&q=fen%20lands%20burning%20peat&f=false