Greenland 2014 Melt Season

[RaenorShine]

 NSIDC melt area fell on 11/8 to back below 20%.

DMI shows melt increasing on the west coast. Daily SMB loss increased to around 4Gt.

[RaenorShine]

Basic melt area fell back to just over 10% on 12/8 before rebounding to around 15% on 13/8.

DMI shows another band of precipitation taking the net daily SMB to zero. (13/8)

[RaenorShine]

DMI shows the precipitation stall being the dominant feature on 14/8. DMI SMB daily loss was around 0.5Gt.

[RaenorShine]

NSIDC melt area went down on 14/8 to just over 10%.

DMI shows the heavy precipitation moving away, but melt also lessening. Daily SMB loss increased slightly to 1Gt.

[RaenorShine]

NSIDC melt area continued to fall on 15/8 to around 10%.

DMI shows another pulse of precipitation moving in to the west on 16/8. Daily SMB shows a small net gain.

We are now at the end of the standard melt season (DMI start the season in September, but the  1990-2011 mean curve hits its minimum around now. It's too early to call the minimum SMB for this year, but the curve has flattened out significantly over the past couple of weeks. 

2014 has been a quiet one for surface mass loss, with DMI showing less mass loss than both 2013 (around 75Gt lower) and 2012(around 125Gt lower), but still well above the long term average. How much of the difference is due to the new algorithm being used I am not sure.  We'll have to wait for the DMI review later in the year.

NSIDC melt area looks to have been above 2013 (which had a large dip in late June-early July). Although we have not quite hit the 2013 maximum melt area, we have been constantly above the 1981-2010 average for most of the melt season.

[RaenorShine]

NSIDC melt area shows a slight uptick to around 12% (16/8).

DMI shows heavy melt along the western edge of the sheet, but more precipitation (again) which is winning the battle late in the season. DMI shows the first significant daily SMB gain since early June of 1Gt (17/8).

[Rubikscube]

Wow, the last week's (today's in particular) SMB and melt area maps are really interesting. My interpretation is that some of the blue areas further inland (SMB map), indicating mass gain, migth actually be rain that the DMI model assumes would not be able to exit the ice sheet thus being counted as mass gain while having a net damaging effect on the ice sheet, such as causing reduced albedo. I cannot recall having seen such extensive rain events impacting West Greenland many times before, not last year at least. Anyone who can tell how unusual/usual this is?

There also seems to be more of both rain and generally hot weather to come for western and southern Greenland during the next few days. A most interesting end to the season.

[Frivolousz21]

GIS albedo has been bad quite often this summer.  I have zero faith in that model.

[RaenorShine]

Wow, the last week's (today's in particular) SMB and melt area maps are really interesting. My interpretation is that some of the blue areas further inland (SMB map), indicating mass gain, migth actually be rain that the DMI model assumes would not be able to exit the ice sheet thus being counted as mass gain while having a net damaging effect on the ice sheet.........

That's the way I see it also. Some of the precipitation will be snow, but especially at lower levels it will be classed as trapped rain. After a few of the earlier storms melt has come back stronger after it has passed in the model, a sure sign of such damage being taken into account.

GIS albedo has been bad quite often this summer.  I have zero faith in that model]

Albedo isn't the only requirement for extensive melt though. It's been a cool summer especially in the south, with a few hot days. No model or measurement method is going to be perfect. Blaming the model/measurements when they do not support your view has been practiced on 'the dark side' for a while now and does not add to the discussion.

One way to evaluate a model is to look at its output vs real world measurements. For SMB we have to wait for Grace measurements. But DMI now have a daily output for melt area from their model on http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/. The graph looks remarkably similar to the measured output from NSIDC.

[RaenorShine]

NSIDC shows melt right across the saddle on 17/8. Melt area increased to over 20% of the sheet.

DMI shows extremely heavy precipitation moving north again. Daily SMB gain was similar to yesterday at 1Gt(18/8).

[Frivolousz21]

Albedo is by far the most important requirement for sustained melt.  A small albedo change is way more important then a small temperature change.

Just a small snapshot of the West/SW GIS ice sheet versus 2009 shows why 2014 is going to come in with a top 3 melt season.

that is nasty and it's getting late in the year.  there is still visible melt water, visible lakes, and the dark layer is visible with it's low albedo soaking in the waning sun.

[RaenorShine]

NSIDC shows a slight decrease to under 20% melt area (18/8).

DMI shows the heavy precipitation moving north and lessening significantly. Melt is still strong, so we have a large uptick in mass loss. Daily SMB loss was 4.5Gt on 19/8. This has more than reversed the alcoholic days of gain.

[crandles]

"The contribution of both ice sheets together to sea level rise has doubled since 2009," said Angelika Humbert from Germany's Alfred Wegener Institute.

"To us, that's an incredible number," she told BBC News.

http://www.bbc.co.uk/news/science-environment-28852980

Sounds like it is still doubling every 5 years.

OTOH  "taken just over two years' worth of data centred on 2012/2013" and
"When compared with similar data-sets assembled by the US space agency's IceSat mission between 2003 and 2009"
might indicate 2006 to 2012.5 for 6.5 years average gap.

[crandles]

The paper
http://static2.egu.eu/media/filer_public/ac/f2/acf2d697-4a67-433b-bfd4-2a1f569cdb86/tc-2014-18.pdf

says

For Greenland we find a volume loss increased
by a factor of 2.5 compared to the ICESat period

Factor of 2.5 over 6.5 years is about a doubling every 5 years.

[RaenorShine]

NSIDC melt area rebounded back to the 20% Mark on 19/8.

DMI shows heavy melt continuing despite the precipitation. Daily SMB loss was more or less unchanged at 4.5Gt.

Another confirmation of our impact on Greenland Crandles. At what point on the exponential melt curve will the world start doing something about it?

[RaenorShine]

Basic melt area increased again on  20/8 to around 22%.

DMI shows larger areas of light precipitation on 21/8.daily SMB loss fell back slightly to 3.5Gt.

Both measurements are exceptionally high for this time of year. NSIDC shows melt area outside of its 2sd area. DMI shows us well outside its 1990-2011 historic range in grey (although they do drop the highest and lowest values for some reason).

[Frivolousz21]

Melt area is up to 30% now or close to it.

[RaenorShine]

As friv pointed out above, melt area increased to around 30% on 21/8.

DMI shows significantly less melt on 22/8, with similar precipitation.  Daily SMB loss fell to almost zero.

The Albedo map looks really bad at the moment, with the whole of the southern peninsula of greenland showing 15%+ anomaly.

Robertsscribbler has a blog on Greenland on the effects of the recent weather.

http://robertscribbler.wordpress.com/2014/08/21/greenlands-late-august-rain-over-melt-ponds-is-a-glacial-outburst-flood-hazard/

Greenland’s Late August Rain Over Melt Ponds is a Glacial Outburst Flood Hazard

Glacial melt ponding on steep ice faces. Above freezing temperatures for an extended period. Storms delivering rainfall to the glacier surface.

These three events are a bad combination and one that, until recently, we’ve never seen before for Greenland. It is a set of circumstances directly arising from a human-driven warming of the great ice sheet. And it is one that risks a highly violent and energetic event in which melt ponds over-top and glaciers are flushed and ripped apart by surges of water rushing for scores of miles over and through the ice sheet. Major melt pulse events called glacier outburst floods that can result in catastrophically large volumes of water and broken ice chunks issuing from the towering, melting glaciers of Greenland and Antarctica.

[RaenorShine]

NSIDC shows melt area halving on 22/8 to 15%. This is still well above the average though.

DMI shows further decreases in melt (with virtually no melt in the north), and another large pulse of precipitation in the west. Daily SMB balance has moved firmly into gain of 2Gt (23/8).

[RaenorShine]

NSIDC shows melt area almost unchanged at 15% (23/8)

DMI shows precipitation lessening slightly, with mlet again limited to the souther peninsula.  Daliy SMB gain fell to under 1Gt (24/8).

NSIDC have also posted a summary of the melt season a couple of days ago that I have only just seen.

http://nsidc.org/greenland-today/2014/08/greenlands-summer-the-pressure-is-on-and-off/

Greenland’s summer: The pressure is on, and off

Melting on the surface of the Greenland Ice Sheet in June and July 2014 has been well above the 1981 to 2010 average in most areas, but after a fast start in May, the southern region and the southeastern coast have seen lower-than-average melt. Mid-summer surface melting did not reach higher elevations (above 2000 meters) as often as in the reference period 1981 to 2010. Short bursts of extensive melting were related to periods of high air pressure over the ice sheet favoring sunny conditions, and promoting increased melting in darker areas of the ice sheet (wet snow, bare ice, or dirty snow).

[RaenorShine]

 NSIDC shows melt area falling slightly again, but still around 15% 24/8.

DMI shows a similar picture to yesterday. Daily SMB gain increased slightly to just over 1Gt 25/8.

[RaenorShine]

NSIDC shows melt area dropping to under 10%(25/8).

DMI shows melt decreasing still further. Daily SMB gain has increased to 2Gt(26/8).

[RaenorShine]

Nsidc shows a further drop to 5% (26/8)

DMI shows a similar pattern to yesterday. Daily SMB gain was 1.5 Gt (27/8).

[RaenorShine]

NSIDC shows melt area at around the same level (5%- 27/8)

DMI shows heavy precipitation in the south. Daily SMB Gain increased to 3.5Gt (28/8)

[RaenorShine]

NSIDC Melt area remains at 5% - 28/8

DMI shows the heavy precipitation moving up the west coast. Daily SMB Gain increased  to 4.5Gt (29/8)

With the last couple of days its evident we have passed the minimum SMB for the season so I am going to stop the daily updates. If I see any major melt pulses I'll add a further post.

[Espen]

RaenorShine,

Thanx for the updates and the work done