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Author Topic: Greenland 2019-20 SMB (Snowfall & Melting) Year  (Read 22026 times)

FrostKing70

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #50 on: March 02, 2020, 11:24:13 PM »
Thank you, that was very helpful!   

As I look at the overlay, it appears the equilibrium line on the south side is close to the 1,500 meters mentioned in the article, and climbs upward the farther north we go on the ice sheet. 

Makes perfect sense now that I see it, but I was not mentally adjusting for how long the GIS is from south to north and the associated temperature and isolation differences!

oren

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #51 on: March 03, 2020, 07:00:25 AM »
Nice work Tor.
I would have thought the equilibrium elevation would be lower. You learn something new every day.

sidd

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #52 on: March 03, 2020, 08:08:17 AM »
I keep careful watch on the saddle at 67N between north and south domes. When ELA consistently exceeds that, saddle collapse has begun. We are very close.

sidd

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #53 on: March 11, 2020, 07:35:29 PM »
http://polarportal.dk/en/greenland/surface-conditions/ as at 10 March 2020


Accumulated Data 1 Sept 2019 to 10 March 2020

Melt From now of zero consequence probably until next April.

and

PRECIPITATION Snowfall tending a bit more below than above average- result.....

SMB continues well below average, over 50 GT , circa 15% less than average

SMB much above average in the coastal SE, NE, & NW.
Elsewhere average or well below average.
________________________________________________________________________
Quotes from DMI
Quote
The Greenland Ice Sheet evolves throughout the year as weather conditions change. Precipitation increases the mass of the ice sheet, whilst greater warmth leads to melting, which causes it to lose mass. The term surface mass balance (SMB) is used to describe the isolated gain and loss of mass of the surface of the ice sheet – excluding the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.

Melting does not in itself necessarily give rise to mass loss, however. Much of the meltwater will refreeze in the surface snow layers rather than running off the ice sheet, and this process is included in the calculations of surface mass balance which is why the melt area plot may differ from the areas of negative mass balance seen on the map “Daily change”. Likewise, sublimation does not count as melting and surface mass balance can therefore occur with the surface temperature being far below the melting point.
_______________________________________________________________
[/quote]
[/quote]
"Para a Causa do Povo a Luta Continua!"
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grixm

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #54 on: March 15, 2020, 11:32:35 AM »
The Freya glacier webcam is back up and the sun has started to come out. There's not that much snow, either.

https://www.foto-webcam.eu/webcam/freya1/

PS: Is this thread just for SMB data? If so, there is no general 2020 greenland season thread yet.

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #55 on: March 15, 2020, 12:45:28 PM »

PS: Is this thread just for SMB data? If so, there is no general 2020 Greenland season thread yet.
Due to being in a hurry I forgot to add in the title GRACE-FO Greenland Ice Sheet (GIS) Mass Loss.
But this is where I post the GIS monthly data from the GRACE-FO project.

You are correct, there are a large number of threads about different specialised aspects of Greenland, but not a general thread.

But keep those images coming, please - makes the thread more interesting and a sunny day now means melt.
« Last Edit: March 15, 2020, 03:29:13 PM by gerontocrat »
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Stephan

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #56 on: March 16, 2020, 10:13:43 PM »
grixm,
thank you for posting the Freya webcam picture. It was off-line for quite a while now, so I didn't notice it is working again.
I invite all of you to visit that website. You can easily play around and look at the situation in the previous years (2019 it was off). In my opinion the March 2020 snow is much less than in the year 2018 and less than in 2017 and 2016 (different position of the webcam).
It is too late just to be concerned about Climate Change

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #57 on: March 17, 2020, 11:43:14 PM »
http://polarportal.dk/en/greenland/surface-conditions/ as at 16 March 2020


Accumulated Data 1 Sept 2019 to 16 March 2020

Melt Not long until April - when will the first day of -ve SMB gain be?

and

PRECIPITATION Snowfall very much below average in the last week- result.....

SMB continues well below average, maybe 75 GT , circa 20% less than average

SMB much above average in the coastal SE, NE, & NW.
Elsewhere average or well below average.

Dry days also mean sunny days - surface melt tends to reduce albedo of snow, though not enough melt yet for run-off?
________________________________________________________________________
Quotes from DMI
Quote
The Greenland Ice Sheet evolves throughout the year as weather conditions change. Precipitation increases the mass of the ice sheet, whilst greater warmth leads to melting, which causes it to lose mass. The term surface mass balance (SMB) is used to describe the isolated gain and loss of mass of the surface of the ice sheet – excluding the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.

Melting does not in itself necessarily give rise to mass loss, however. Much of the meltwater will refreeze in the surface snow layers rather than running off the ice sheet, and this process is included in the calculations of surface mass balance which is why the melt area plot may differ from the areas of negative mass balance seen on the map “Daily change”. Likewise, sublimation does not count as melting and surface mass balance can therefore occur with the surface temperature being far below the melting point.
_______________________________________________________________
[/quote]
[/quote]
[/quote]
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #58 on: March 21, 2020, 08:19:03 PM »
http://polarportal.dk/en/greenland/surface-conditions/ as at 20 March 2020


Accumulated Data 1 Sept 2019 to 20 March 2020

Melt Not long until April - when will the first day of  SMB loss be?

and

PRECIPITATION Snowfall very much below average in the last week until this day - when snow drought ended. But GFS says precipitation low for the next 5 days result - see image of cumulative precipitation 21-26 March..... result being...

SMB remains well below average by maybe 75 GT , circa 20%.

SMB much above average in the coastal SE, NE, & NW.
Elsewhere average or well below average.

Dry days also mean sunny days - surface melt tends to reduce albedo of snow, though not enough melt yet for run-off?
________________________________________________________________________
Quotes from DMI
Quote
The Greenland Ice Sheet evolves throughout the year as weather conditions change. Precipitation increases the mass of the ice sheet, whilst greater warmth leads to melting, which causes it to lose mass. The term surface mass balance (SMB) is used to describe the isolated gain and loss of mass of the surface of the ice sheet – excluding the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.

Melting does not in itself necessarily give rise to mass loss, however. Much of the meltwater will refreeze in the surface snow layers rather than running off the ice sheet, and this process is included in the calculations of surface mass balance which is why the melt area plot may differ from the areas of negative mass balance seen on the map “Daily change”. Likewise, sublimation does not count as melting and surface mass balance can therefore occur with the surface temperature being far below the melting point.
_______________________________________________________________
« Last Edit: March 21, 2020, 08:26:48 PM by gerontocrat »
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #59 on: March 28, 2020, 12:55:59 PM »
http://polarportal.dk/en/greenland/surface-conditions/ as at 27 March 2020


Accumulated Data 1 Sept 2019 to 27 March 2020

Melt Not long until April - when will the first day of  SMB loss be?
On Sunday 29th a brief spell of above freezing temps on the SW coast - but cloud and rain/snow mix, so not enough warmth for a net SMB loss?

and

PRECIPITATION Snowfall mostly below average in the last week.
GFS says precipitation snow/rain on the 28th and 29th, then a snow drought for the foreseeable future.

SMB remains well below average by maybe 75 GT , circa 20%.

SMB much above average in the coastal SE, NE, & NW.
Elsewhere mostly average to well below average.
________________________________________________________________________
Quotes from DMI
Quote
The Greenland Ice Sheet evolves throughout the year as weather conditions change. Precipitation increases the mass of the ice sheet, whilst greater warmth leads to melting, which causes it to lose mass. The term surface mass balance (SMB) is used to describe the isolated gain and loss of mass of the surface of the ice sheet – excluding the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.

Melting does not in itself necessarily give rise to mass loss, however. Much of the meltwater will refreeze in the surface snow layers rather than running off the ice sheet, and this process is included in the calculations of surface mass balance which is why the melt area plot may differ from the areas of negative mass balance seen on the map “Daily change”. Likewise, sublimation does not count as melting and surface mass balance can therefore occur with the surface temperature being far below the melting point.
_______________________________________________________________
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Tor Bejnar

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #60 on: March 28, 2020, 02:19:33 PM »
I don't think of the Humboldt Glacier and doing much (off of Kane Basin in the NW part of Greenland - basically where the large light pink area is), but the light pink is suggestive more ice is moving that what meets the eye (or at least 'my eye').
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #61 on: April 03, 2020, 10:37:54 PM »
I missed the first melt event of this year on March 30 & 31 (and an almost invisible spot on April 1.

Here is March 31...
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #62 on: April 11, 2020, 03:27:01 PM »
http://polarportal.dk/en/greenland/surface-conditions/ as at 10 April 2020


Accumulated Data 1 Sept 2019 to 10 April 2020

Melt 3 weeks after Solstice - when will the first day of  SMB loss be?
On Sat 11th & Sunday 12th a spell of above freezing temps on the SW coast - enough warmth for a net SMB loss? Certainly should show up on the melt graphics.

and

PRECIPITATION A big dump a wekk ago and then snowfall mostly below average in the last week.

SMB remains well below average by maybe 75 GT..

SMB much above average in the coastal SE, NE, & NW.
Elsewhere mostly average to well below average.
________________________________________________________________________
Quotes from DMI
Quote
The Greenland Ice Sheet evolves throughout the year as weather conditions change. Precipitation increases the mass of the ice sheet, whilst greater warmth leads to melting, which causes it to lose mass. The term surface mass balance (SMB) is used to describe the isolated gain and loss of mass of the surface of the ice sheet – excluding the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.

Melting does not in itself necessarily give rise to mass loss, however. Much of the meltwater will refreeze in the surface snow layers rather than running off the ice sheet, and this process is included in the calculations of surface mass balance which is why the melt area plot may differ from the areas of negative mass balance seen on the map “Daily change”. Likewise, sublimation does not count as melting and surface mass balance can therefore occur with the surface temperature being far below the melting point.
_______________________________________________________________
[/quote]
"Para a Causa do Povo a Luta Continua!"
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Tor Bejnar

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #63 on: April 11, 2020, 03:45:56 PM »
IIRC from a discussion last year, the greyed areas on the Greenland melt charts (SMB daily and SMB annual accumulated) show a range from '2nd highest' to '2nd lowest' values.  Where the red 2011-12 line goes off by itself, it shows the record year off by itself.  On the daily record, the 2019 blue line is off by itself for a day at the end of September.  (See the spot of 'white' above the blue "V" on the attached enlargement.  There is also a record daily high earlier in the month, also shown.)  Other peaks and dips might also be records, but the lines are too thick to show any 'white'.
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oren

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #64 on: April 12, 2020, 12:03:47 AM »
Gerontocrat, thank you for these reliable updates. I noticed the last one did not include the 2018-19 line, if you could put it back it would be much appreciated. I am kinda hoping this year will pick up some extra snow soon, like last year did around this time.

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #65 on: April 12, 2020, 02:28:50 PM »
Gerontocrat, thank you for these reliable updates. I noticed the last one did not include the 2018-19 line, if you could put it back it would be much appreciated. I am kinda hoping this year will pick up some extra snow soon, like last year did around this time.
DMI took last year off the graph. They did the same last year.

No point in contacting them - they do not answer emails, e.g. I have asked for any chance of getting daily SMB data as a txt, csv, xls file. They have it, they obviously aren't inclined to give it.

So I have no numeric data from this site. Maybe I should try NSIDC ?

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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #66 on: April 14, 2020, 02:17:43 PM »
I missed the first day of SMB loss in calendar year 2020.

It was on April 11th - due to almost zero precipitation and, according to DMI, sublimation, i.e. not surface melt. Meanwhile NSIDC say there was surface melt on that day.

Sublimation makes sense as it is snow turning into vapour, which reduces snow mass (SMB). Surface melt, if in small quantities, is likely to just soak into the snow surface without run-off, i.e. no loss of mass.
__________________________
ps: On the 12th DMI shows surface melt - at the snowline edge near the SW coast..
But it also snowed, and likely rained at lower levels.

So no SMB loss, but the surface melt on this day likely to have been caused by rain at the lowest levels, not sunshine.

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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #67 on: April 15, 2020, 03:22:51 PM »
GRACE-FO data on the GIS mass change to Feb 2020 released
- ftp://isdcftp.gfz-potsdam.de/grace-fo/GravIS/GFZ/Level-3/ICE/GIS/

Annual GIS mass loss 431 GT (= 1.2 mm sea level rise), of which 256 GT was in the West (see map attached)
Total mass loss since 2002 3,800 GT (= 10.5 mm sea level rise).

i.e. last 12 month rate of SLR double the average of 2002-2020.

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FrostKing70

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #68 on: April 16, 2020, 03:16:07 AM »
The GRACE graph seems to be nearly linear for 3 years (2017 to 2019?), without the annual increase and decrease seen in all the other years.  Doesn't seem like real data, even though it meanders a bit towards the end.  Is there an explanation?

 

wdmn

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #69 on: April 16, 2020, 04:27:00 AM »
The GRACE graph seems to be nearly linear for 3 years (2017 to 2019?), without the annual increase and decrease seen in all the other years.  Doesn't seem like real data, even though it meanders a bit towards the end.  Is there an explanation?

The GRACE mission ended 2017, and GRACE-FO was not launched until May 2018, so there was a period without any data collection.

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #70 on: April 16, 2020, 02:00:18 PM »
The GRACE graph seems to be nearly linear for 3 years (2017 to 2019?), without the annual increase and decrease seen in all the other years.  Doesn't seem like real data, even though it meanders a bit towards the end.  Is there an explanation?
GRACE started to die in mid 2017, many years beyond its expected life.
The regular monthly updates from GRACE-FO started from October 2018. Hence the odd bit on the graph for that period. Since my and LibreOffice's graphing skills are limited - that's all, folks.

This is the data for that interregnum (posh word, what?)
 
YEAR    Measure   DATE   Cumulative Mass Loss
2017.360   -1,631   May-2017   -3045.819
2017.440   -1,640   Jun-2017   -3054.616
2018.455   -1,825   Jun-2018   -3239.049
2018.520   -1,824   Jul-2018   -3238.588
2018.831   -1,915   Oct-2018   -3329.073
2018.873   -1,916   Nov-2018   -3330.541
2018.957   -1,897   Dec-2018   -3311.348
_______________________________________________
interregnum
noun
- a period when normal government is suspended, especially between successive reigns or regimes.
- the period in English history from the execution of Charles I in 1649 to the Restoration of Charles II in 1660.
- an interval or pause between two periods of office or other things.
"the interregnum between the discovery of radioactivity and its detailed understanding"
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #71 on: April 21, 2020, 03:33:17 PM »
Melt from Rain

http://polarportal.dk/en/greenland/surface-conditions/

I for one, always associate melt in Greenland with Sunny Days, i.e. from insolation (+ a warmer atmosphere).

But last year I came across a paper entitled...
"Increased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusions", i.e. rain. ( https://www.the-cryosphere.net/13/815/2019/ )

And here is an example - on the attached  the blue patch is intense precipitation on the 20th April. One assumes - SNOW!
But at the snowline edge, there was melt on that day, the little bits of red on the melt graph. It must be due to precipitation at the edge as rain, not snow.

So as the years go by, it could be rain, not sunny days, that causes a catastrophic increase in Greenland melt.
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kassy

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #72 on: April 21, 2020, 03:49:13 PM »
Or they could take turns.  ;)

Cool find. Do you expect more of this in the coming month?
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #73 on: April 21, 2020, 04:52:01 PM »
Or they could take turns.  ;)

Cool find. Do you expect more of this in the coming month?
Yes - depending on the weather bringing warmth & moisture.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #74 on: April 21, 2020, 05:56:58 PM »
SMB & melt Data

Ruth Mottram & The DMI have come up with a hhh...uuuuuu,,,,gggge basket of goodies.
& it is not my birthday.
Boredom of self-isolation at bay for a few days?
SMB data + Grace-FO data cshould be interesting

ps: When I wrote to them some time ago I gave the ASIF quite a big plug.
________________________________________

Quote
Ruth Mottram <rum@dmi.dk>
20 Apr 2020, 10:30 (1 day ago)
to me, info@polarportal.dk, Martin

Dear xxxxxx   
Quote
(Gerontocrat is being coy as to his identity today)
thanks very much for your message, and many apologies for the late response - I recently found the reply I thought I'd sent to you in my drafts folder, apparently it did not send.

However, the reason I was looking for your mail address was to let you know some good news. We have decided to make our datasets much more easily available and they are now once again up on our server. .
You can grab the daily updated numbers here:


http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/GSMB_2020.txt


and the previous years are available here:

http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/


I'd liek to emphasise that these are model products and as we hopefully make clear in the disclaimer, they are provided only for information and may change. A different model may get slightly different results!

If you need more information or help in understanding the numbers, please don't hesitate to get in touch


Best wishes


Ruth Mottram
« Last Edit: April 21, 2020, 06:22:08 PM by gerontocrat »
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blumenkraft

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #75 on: April 21, 2020, 07:00:14 PM »
Thanks so much, Ruth. And you too, Gero!
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #76 on: April 22, 2020, 10:56:05 PM »
Another (bigger) dose of melt from rain.
Yet another fight between warmth & cold.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #77 on: April 23, 2020, 05:42:01 AM »
http://polarportal.dk/en/greenland/surface-conditions/ as at 22 April 2020


Accumulated Data 1 Sept 2019 to 22 April 2020


Sublimation (on the West coast), MELT and precipitation (both on the East coast) all on the same day.

PRECIPITATION greater than melt so SMB daily increase mostly above average in recent days.

Accumulated SMB still somewhat below average.

WARMTH persisting until at least Sunday 26th April should produce more melt.
________________________________________________________________________
Quotes from DMI

Quote
The Greenland Ice Sheet evolves throughout the year as weather conditions change. Precipitation increases the mass of the ice sheet, whilst greater warmth leads to melting, which causes it to lose mass. The term surface mass balan 2ce (SMB) is used to describe the isolated gain and loss of mass of the surface of the ice sheet – excluding the mass that is lost when glaciers calve off icebergs and melt as they come into contact with warm seawater.

Melting does not in itself necessarily give rise to mass loss, however. Much of the meltwater will refreeze in the surface snow layers rather than running off the ice sheet, and this process is included in the calculations of surface mass balance which is why the melt area plot may differ from the areas of negative mass balance seen on the map “Daily change”. Likewise, sublimation does not count as melting and surface mass balance can therefore occur with the surface temperature being far below the melting point.
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oren

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #78 on: April 23, 2020, 05:50:31 AM »
Just like last year, the 2nd half of April is delivering some of the missing snow. Hopefully this will continue.

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #79 on: April 25, 2020, 03:55:41 PM »
http://polarportal.dk/en/greenland/surface-conditions/

The coast of the southern half of Greenland (i.e. at low altitude) is above freezing.

The 23rd saw much precipitation and much melt b= above average increase in SMB
the 23th saw almost no precipitation and much melt = almost zero increase in SMB.
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Sublime_Rime

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #80 on: April 25, 2020, 07:51:44 PM »
Melting events over past couple days seems to have reduced albedo (bluish tint) over the lower-altitude areas on the east and west coasts of central Greenland. Senior posters: Does this seem significantly early for this to occur? Likely to precondition continued melt in these areas?

Looks like forcast calls for another 3-4 days at least of significantly high temp anomalies for greenland as a whole, before returning to normal later in the week.

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #81 on: April 26, 2020, 02:17:14 PM »
http://polarportal.dk/en/greenland/surface-conditions/

A spike in melting April is earlier than average, but in these years it would feel strange not to have an event in April.

Meanwhile, the weather had a busy day yesterday (25 April), sublimation, melt and precipitation. Result - average SMB daily gain.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #82 on: April 27, 2020, 08:26:34 AM »
First bash at SMB data released by DMI attached.
See http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Hope to be looking at the SMB data against GRACE-FO data later this week.
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oren

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #83 on: April 27, 2020, 02:09:59 PM »
Nice! Now they just need to add back the 1981-2010 mean.
And now I can see the late April upswing this year is smaller than last year.

gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #84 on: April 27, 2020, 04:46:19 PM »
Nice! Now they just need to add back the 1981-2010 mean.
And now I can see the late April upswing this year is smaller than last year.
and to give the data split into the drainage basins.
But which drainage basin definition and map are they using?
There is the map used for GRACE-FO data, and there is the map used by e.g.
Eric Rignot et al in the PNAS paper "Forty-six years of Greenland Ice Sheet mass balance
from 1972 to 2018"  See attached

also attached is 1st bash at the melt data - which is in % area. The cumulative figure is a totally  unscientific rough guide to the intensity of the melting season. Simply put, if daily melt % is 25% for 4 days in a row, that gives a cumulative melt day of 1.
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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #85 on: April 27, 2020, 10:03:19 PM »
very nice, gerontocrat.
Looks like there is a lot of spreadsheet work ahead of you. Good luck with that, and looking forward for further nice charts...
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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #86 on: April 28, 2020, 08:21:41 PM »
Sometimes it is good to look beyond the land to the surrounding seas.

To Greenland's West is Baffin Bay - with a sea ice area at lowest in the satellite record for the last 21 days, currently a country mile below 2nd placed 2005. The West coast is nearly sea ice free up to and beyond 70 North.

To the East is the Greenland Sea - and despite loads of ice export from the Fram, sea ice area on the southern coast (up to 70 North) is well below average, and north of that looking pretty ropy.

i.e. the Southern half of Greenland is totally (as near as makes no difference) exposed to weather coming in from an open water ocean. I do not know how this compares with an average year and the resulting impact of earlier open water ocean weather systems on snowfall, rain and melting (SMB) and glacial melt both on land and under marine terminating glaciers (total GIS mass balance). But I doubt it will do the Greenland Ice Sheet any favours.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #87 on: April 30, 2020, 10:59:37 PM »
Linking DMI & GRACE-FO data

GRACE-FO gives us the changes  in the NET MASS BALANCE of Greenland.
DMI now gives us the change in surface Mass Balance (SMB)

So we now have a simple equation.

GROSS MASS Change = NET MASS loss (gain) + SMB gain (loss), and that mass change is (almost) always a mass loss.

The attached table and graph shows that the gross mass loss increases every month - even in winter. i.e. glacial melt, mostly from marine-terminating glaciers continues all winter by not a small amount.
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ps: If DMI give data for years before 2018 (2017-18 were the years of no or sporadic GRACE data) then the table & graph can be extended backwards).
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #88 on: May 01, 2020, 03:13:18 PM »
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Greenland SMB @ 30 April

In the last few days continuous melt on the coastal fringe of southern Greenland (especially the East coast) + a mixture of sublimation & precipitation & dry periods.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #89 on: May 09, 2020, 06:49:32 PM »
http://polarportal.dk/en/greenland/surface-conditions/
https://climatereanalyzer.org/wx/fcst_outlook/

The somewhat substantial probable warming event in the Arctic for the next 5-10 days looks like having only a limited effect on Greenland.

Melting on the Southern coasts and maybe fairly dry except for in the usual place - the SE corner.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #90 on: May 12, 2020, 03:01:39 PM »
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/


So far melting remains modest, and SMB gain this season also well below average.
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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #91 on: May 12, 2020, 04:22:00 PM »
It will be interesting to see if the line this year remains below last years, and thus turns down in the next ~2 weeks.

Combine that with the predictions that this year has a 75% chance of being the warmest year on record, and it should make for an interesting summer in Greenland.

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #92 on: May 14, 2020, 10:18:35 AM »
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/


So far melting remains modest,but persistent , and gradually increasing, while SMB gain this season also well below average.

With above average ocean open water, especially on the West coast, forecasts of a long hot year, the possibility of large mass losses from the GIS must be above average.
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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #93 on: May 16, 2020, 12:35:47 AM »
On the melting season thread much talk about pre-conditioning.
Perhaps the same applies to the Greenland spring & summer.

The two images attached show how the southern half of Greenland is now totally exposed to open water ocean - and that ocean is already warming up. (Sea ice in Baffin Bay has been lowest in the satellite record for 38 days in a row.)

Weather arriving from the open water ocean is somewhat different from that which passes over an expanse of frozen water.
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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #94 on: May 16, 2020, 08:54:26 AM »
On the melting season thread much talk about pre-conditioning.
Perhaps the same applies to the Greenland spring & summer.

The two images attached show how the southern half of Greenland is now totally exposed to open water ocean - and that ocean is already warming up. (Sea ice in Baffin Bay has been lowest in the satellite record for 38 days in a row.)

Weather arriving from the open water ocean is somewhat different from that which passes over an expanse of frozen water.

It's definitely seen huge preconditioning.



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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #95 on: May 16, 2020, 12:25:42 PM »
http://polarportal.dk/en/greenland/surface-conditions/

Melt, though not large, is persistent, not quite enough to result in an SMB loss, but enough to keep daily surface mass gain very much below average.

Looking at the GFS forecast suggests many more days of the same - a slow burn.
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gerontocrat

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #96 on: May 17, 2020, 11:19:22 AM »
Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/


SMB gain is zero on this day (16May).
But despite the considerable area of melt and little snowfall, surface mass did not reduce. I presume this is because the DMI model is assuming that much of the current melt is not leading to run-off, i.e. the water from melted surface snow is sinking into the top lowers of snow.

My guess is that this is a potential considerable uncertainty in the output from the model. I believe there is only one station with a long-term record of river discharge (Watson River discharging into Baffin Bay). Greenland needs more weather stations!

Accumulated SMB gain this year at 500GT is about 50GT below the average.
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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #97 on: May 17, 2020, 02:00:24 PM »
But despite the considerable area of melt and little snowfall, surface mass did not reduce. I presume this is because the DMI model is assuming that much of the current melt is not leading to run-off, i.e. the water from melted surface snow is sinking into the top lowers of snow.

There is also the water that penetrates the glacier, but freezes or remains trapped inside the glacier without joining the sub-glacial water circulation system.
Which is actually very difficult to model

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #98 on: May 17, 2020, 04:55:36 PM »
Meanwhile, GFS forecasts for the next 10 days

- West & Central Greenland will be dry as a bone. Even the modest precipitation in the East will be mostly confined to the coastal fringe. The usual exception is that small area in the SE Corner.

- AVERAGE (and the daily forecast) temperatures imply continual melting on the SW coastal quarter.

My guess is that some days will see a modest SMB loss - and if not, well below average SMB gain.

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FrostKing70

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Re: Greenland 2019-20 SMB (Snowfall & Melting) Year
« Reply #99 on: May 17, 2020, 08:54:26 PM »
Sounds like we are set up to nearly flat line on accumulation for the next 7 to 10 days, which will get us to the point in the year where, at least in recent years, we have tipped over to loss for the summer...
« Last Edit: May 17, 2020, 09:11:37 PM by FrostKing70 »