Author Topic: Greenland 2020-21 SMB, melting and GRACE mass (Read 61116 times)

gerontocrat · « **on:** September 05, 2020, 12:30:00 PM »

I am starting this thread so these posts conform to the DMI Greenland Year September to August as in their website http://polarportal.dk/en/greenland/surface-conditions/.

Also,I will plonk GRACE-FO data on overall Greenland Ice Sheet Mass here (when I get it).

The Greenland 2019-20 melting Season thread is staying open, as there will be many year end reports coming out in the next few months.

Here are the daily & cumulative graphs for 4 September.

gerontocrat · « **Reply #1 on:** September 06, 2020, 12:12:07 PM »

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

The new DMI year for SMB starts while the DMI keeps the old year for melt open. Too complicated for little me.

Data as at 5 Sep 2020.

Melt a respectable 7.4% of the surface area of Greenland.

Precipitation high(ish).
The result is a daily SMB gain of 2.2 GT.

Cumulative SMB gain for the year is 4.5 GT.

Melt may persist though reducing
A succession of lows bringing a mixture of rain and snow may well mean precipitation is high

SMB gains - maybe some large - in prospect.
_________________________________________________________________
Updates will be less frequent from now, depending on any unusual SMB gains or lack of gains.
Click on images for full size view.

gerontocrat · « **Reply #2 on:** September 13, 2020, 10:57:21 AM »

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Data as at 12 Sep 2020.

Melt has reduced to almost zero.

Precipitation quite low this week.

Cumulative SMB gain for the year is 13.4 GT, a little bit below average.

There may be a final blip of melt mid-week.
A succession of lows bringing a mixture of rain and snow may well mean precipitation is high.

SMB gains - maybe some large - in prospect.

Updates will be less frequent from now, depending on any unusual SMB gains or lack of gains.
_________________________________________________________________
Click on images for full size view.

gerontocrat · « **Reply #3 on:** September 16, 2020, 06:29:48 PM »

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Data as at 15 Sep 2020.

Melt did a small blip up to 1.15%.

Precipitation was low this week but on this day a big dump..

Cumulative SMB daily gain high at 4.4 GT, for the year 18.4 GT, a little bit below average.

There may be a final blip of melt today (Wednesday)
A succession of lows bringing a mixture of rain and snow may well mean precipitation is high.

SMB gains - maybe some large - in prospect.

Updates will be less frequent from now, depending on any unusual SMB gains or lack of gains.
_________________________________________________________________
Click on images for full size view.

gerontocrat · « **Reply #4 on:** September 18, 2020, 11:08:53 AM »

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Data as at 17 Sep 2020.

Melt did a small blip up to 2.3% on the 16th

Precipitation high in the last 2 days..

Cumulative SMB daily gain high at 5 GT on the 16th, 2Gt on the 17th, for the year 25.4 GT, almost up to average.

There may be some final blips of melt this month, but very small.
A succession of lows bringing a mixture of rain and snow may well mean precipitation is high.

SMB gains - maybe some large - in prospect.

Updates will be less frequent from now, depending on any unusual SMB gains or lack of gains.
_________________________________________________________________
Click on images for full size.

gerontocrat · « **Reply #5 on:** October 03, 2020, 01:03:04 PM »

Quote from: gerontocrat on September 18, 2020, 11:08:53 AM

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

September 2020 to August 2021 Year

Data as at 2 October 2020.

Melt has petered out to almost zero
Precipitation variable

Cumulative SMB gain 53 GT, a bit below average.

There may be some final blips of melt this month. but very small.

Updates will be less frequent from now, depending on any unusual SMB gains or lack of gains.
As it is somewhat boring at the moment, a gif is attached of melt and smb change to date.
_________________________________________________________________
Click on images for full size.

gerontocrat · « **Reply #6 on:** October 16, 2020, 03:51:58 PM »

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

data to 15 October

Melt has almost stopped. So instead here is a gif of daily SMB gain and cumulative SMB anomaly plus SMB and melt graphs.

Pretty much average snowfall so far.

gerontocrat · « **Reply #7 on:** November 01, 2020, 07:27:30 PM »

Data from...
http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

data to 31 October

No melt since 21 October. So instead here is a gif of daily SMB gain and cumulative SMB anomaly plus SMB and melt graphs.

Pretty much average snowfall so far.

gerontocrat · « **Reply #8 on:** November 11, 2020, 03:28:30 PM »

And here is the September graph of SMB change (from DMI), Greenland mass change (from GRACE-FO), and gross mass loss from calving and glacial melt.

The data basically says Greenland fell asleep in September.

gerontocrat · « **Reply #9 on:** December 02, 2020, 04:22:41 PM »

http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Greenland snowfall so far this year is boringly average.
Nothing remarkable about mass loss either, and the data is late in arriving.

Only posting this to keep the thread alive.

Don't bother with the gif unless you have a decent internet connection and are bored (it's large).

gerontocrat · « **Reply #10 on:** December 07, 2020, 06:23:32 PM »

Germany has put some more GRACE-FO ice-sheet data up @ ftp://isdcftp.gfz-potsdam.de/grace-fo/GravIS/GFZ/Level-3/ICE/

It's always a bit later (to mid Sept 20) than the text files from JPL/PO-DACC, but it's down to basin level.

Looks like a small overall ice mass gain in September, with mass loss in the south and mass gain in the north.

gerontocrat · « **Reply #11 on:** December 22, 2020, 04:10:45 PM »

The average year remains somewhat average

Note that the DMI melt and SMB graphs have daily data up to one day ago, BUT...

The graphs that combine DMI and GRACE-FO data use monthly data mid-month to mid-month. This is because for some reason (unknown to me) the GRACE-FO data is cumulative data to midmonth. So to make a comparison the DMI data has to be mid-month to mid-month.

Note also the GRACE-FO data is always one to two months in arrears (at best).

Final Note - the GIS cumulative mass loss summary GRACE data from JPL is considerably higher than the mass loss data by basin provided by the GFZ German Research Centre for Geosciences in Potsdam. Some time ago I pointed this out to GFZ who said it would be looked at. Nothing back.

gerontocrat · « **Reply #12 on:** January 25, 2021, 01:28:41 PM »

http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Greenland snowfall so far this year is still boringly average. However, a closer look at the accumulated snowfall anomaly map is of interest (image attached).
Overall the anomaly is pretty much zero, but there are strong positive anomalies (i.e. above average snowfall) on the west coast, and especially on the SW coast and southern tip of greenland. Meanwhile there are negative anomalies (i.e. below average snowfall) on the east and north coast.

I also attach the graph of SMB, and graphs that combine DMI and GRACE-FO data using monthly data mid-month to mid-month. This is because for some reason (unknown to me) the GRACE-FO data is cumulative data to midmonth. So to make a comparison the DMI data has to be mid-month to mid-month.

gerontocrat · « **Reply #13 on:** February 17, 2021, 03:43:41 PM »

http://polarportal.dk/en/greenland/surface-conditions/
http://ensemblesrt3.dmi.dk/data/prudence/temp/PLA/PP_GSMB/

Greenland snowfall so far this year is still boringly average. However, a closer look at the accumulated snowfall anomaly map is of interest (image attached).
Overall the anomaly is pretty much zero, but there are strong positive anomalies (i.e. above average snowfall) on the west coast, and especially on the SW coast and southern tip of greenland. Meanwhile there are negative anomalies (i.e. below average snowfall) on the east and north coast.

I also attach the graph of SMB

interstitial · « **Reply #14 on:** February 17, 2021, 09:16:55 PM »

So more than average snowfall in areas were the microclimate has already shifted to warmer and wetter and less snowfall where less change has occurred. Somehow This fails to reassure me about the future.

gerontocrat · « **Reply #15 on:** February 19, 2021, 01:47:16 PM »

Here is the latest GRACE-FO GIS data from Germany - to November 2020. Always one month behind the summary data from the summary data from JPL's PO.DACC system.

It is winter - melting of glaciers continues but overall Mass increases slightly (see next post).

gerontocrat · « **Reply #16 on:** February 19, 2021, 01:56:49 PM »

I attach the graph that shows SMB, Mass loss from glaciers melting, and net mass loss/gain.
i.e. the SMB data from DMI is combined with GRACE-FO GIS Mass data.

The data is to mid Dec 20 for GIS mass and mid-Feb20 for SMB data.

SMB gain is currently greater than mass loss from glacial melting (at this time of year mainly from marine-terminating glaciers), hence overall mass loss gains slightly.

Some climate models tell us that as AGW continues SMB gain may increase in winter as warmer wetter air increases snowfall but eventually annual SMB gain will decline and could be -ve by mid-Century. On average currently annual SMB gain runs at an average a bit above 360 GT.

As usual click image to enlarge

gerontocrat · « **Reply #17 on:** March 11, 2021, 01:21:37 PM »

Here is the latest GRACE-FO GIS data from Germany - to December 2020. Always one or two months behind the summary data from JPL's PO.DACC system.

It is winter, so while sub-surface melting of marine-terminating glaciers continues, SMB gains from snowfall are higher, giving a net mass gain in December.

sidd · « **Reply #18 on:** March 12, 2021, 07:33:37 AM »

Thats a straight line, good to see, as opposed to antarctica results you posted.

sidd

gerontocrat · « **Reply #19 on:** March 17, 2021, 02:06:58 PM »

Snowfall to Mid-March is so average.
JPL have produced GRACE-FO data to January '21.

Compared with 2019, overall loss in mass much slower.

So here is a map and graphs of where we are in Snowfall, Melting, and Ice Sheet Mass Balance in the 20-21 Greenland year.

gerontocrat · « **Reply #20 on:** April 03, 2021, 03:58:00 PM »

Melt !

Yes - a measurable melt big enough for my old eyes to see it on April 2.
On the coast of the Southern tip of Greenland.

May be more and a bit bigger melt events in the next few days.

gerontocrat · « **Reply #21 on:** April 04, 2021, 10:55:30 AM »

Another day, another - slightly bigger - melt.

Stephan · « **Reply #22 on:** April 04, 2021, 08:45:12 PM »

...and it looks like the melting around Grønland's southernmost tip will continue. The 14 day forecast for Narsarsuaq:

be cause · « **Reply #23 on:** April 05, 2021, 09:57:59 PM »

Field Study Sheds New Light on Melt Zone
With data from a rare expedition to Greenland,
https://www.facebook.com/111544252373674/videos/302324291287634

gerontocrat · « **Reply #24 on:** April 06, 2021, 12:16:47 PM »

Quote from: Stephan on April 04, 2021, 08:45:12 PM

...and it looks like the melting around Grønland's southernmost tip will continue. The 14 day forecast for Narsarsuaq:

So here's a little gif and graph (y axes exaggerated x 10 from normal)

FrostKing70 · « **Reply #25 on:** April 13, 2021, 04:57:59 PM »

Pretty standard start to the year.

gerontocrat · « **Reply #26 on:** April 16, 2021, 02:34:38 PM »

Quote from: FrostKing70 on April 13, 2021, 04:57:59 PM

Pretty standard start to the year.

I have been known to use the word - boring. But then again 2012 was boringly average until the melt started. I was hoping that the early meltthis year would be sustained - but it looks like nothing much will happen from now for a week or two at least.

I attach a gif and graph (graph with Y axis exaggerated x 10 from normal ) of the little melt event that did happen during early April.

Sublime_Rime · « **Reply #27 on:** April 25, 2021, 02:41:36 AM »

GFS predicting prolonged heatwave for Greenland, with positive anomalies for nearly the entire area and above freezing for much of southern tip and particularly southwest coast for entirety of 18Z run today. Also accompanied by HP for most of that time. Might the doldrums end soon? Shall we see an early start to Greenland melt season?

Stephan · « **Reply #28 on:** April 25, 2021, 08:04:47 AM »

This is the temeprature and weather forecast for Narsarsuaq, close to the southernmost tip of Grønland.

gerontocrat · « **Reply #29 on:** April 25, 2021, 12:39:07 PM »

Yes, it looks like something like significant melt is on its way for a few days. But note that it is not early compared with recent years. AGW does seem to have made melt start earlier and finish later.
I attach the DMI map and my graph for melt - my graph still has to have an exaggerated y axis to show the melt which is the highest this melt year but still only on 1% of Greenland's area.

I also attach the accumulated SMB anomaly map as at 24 April, showing the large east west variation. It will be interesting to compare that with the map as snowfall and melt vie for supremacy up to the final result at end September.

gerontocrat · « **Reply #30 on:** April 26, 2021, 09:43:56 AM »

Melt is recorded over 2% of the area of Greenland. Note that this does not show on the daily SMB graph. The DMI model assumes that initially the melt does not run-off, but just sinks into the existing snow cover.

However, the SMB graph shows extensive sublimation (light pink on the map) on the West Coast

gerontocrat · « **Reply #31 on:** April 27, 2021, 09:25:01 AM »

Melt even higher on 26 April

click images to enlarge

gerontocrat · « **Reply #32 on:** April 28, 2021, 10:57:29 AM »

Quote from: gerontocrat on April 27, 2021, 09:25:01 AM

Melt even higher on 26 April

And even higher on 27 April

click images to enlarge

Sublime_Rime · « **Reply #33 on:** April 28, 2021, 03:44:54 PM »

Quick question Gerontocrat: Is the offset in the cumulative data shown due to differences in the end of the previous melt season, or for visualization purposes? For example, 2019-2020 seems to be starting of quite a bit higher than 2020-21.

gerontocrat · « **Reply #34 on:** April 28, 2021, 08:12:34 PM »

Quote from: Sublime_Rime on April 28, 2021, 03:44:54 PM

Quick question Gerontocrat: Is the offset in the cumulative data shown due to differences in the end of the previous melt season, or for visualization purposes? For example, 2019-2020 seems to be starting of quite a bit higher than 2020-21.

The former. DMI defines the Greenland Year from Sep 1 to 31 Aug

But what with AGW 'n-all, melt often continues well into September. I decided to keep to the DMI year for consistency. 2019-20 year had more September melt.

Later as melt accelerates, I will be showing the whole year. The current graph dates and y-axes are exaggerated so as to show the early melt.

gerontocrat · « **Reply #35 on:** April 29, 2021, 10:21:51 AM »

Quote from: Sublime_Rime on April 28, 2021, 03:44:54 PM

Quick question Gerontocrat: Is the offset in the cumulative data shown due to differences in the end of the previous melt season, or for visualization purposes? For example, 2019-2020 seems to be starting of quite a bit higher than 2020-21.

And here are the 2 graphs - part year and full year

+ the melt map for this day

gerontocrat · « **Reply #36 on:** April 30, 2021, 01:46:45 PM »

A third day with melt above the average for the time of year

Note also sublimation on the daily SMB image

gerontocrat · « **Reply #37 on:** May 01, 2021, 10:14:29 AM »

On this day the 30th April,

Very low precipitation
less sublimation
less melt
= SMB loss for the first time this season and very early indeed.

click images to enlarge

kassy · « **Reply #38 on:** May 01, 2021, 11:55:01 PM »

What is the usual onset for SMB loss?

gerontocrat · « **Reply #39 on:** May 02, 2021, 10:29:26 AM »

Quote from: kassy on May 01, 2021, 11:55:01 PM

What is the usual onset for SMB loss?

I attach the DMI graph. You will see that an occasional day of SMB loss can happen from the middle of May onwards, with consistent SMB losses usually starting from the 1st week of June. My own graph shows a tiny SMB loss last year on the 11th April - so small that I didn't see it until I exaggerated the y-axis on my graph by 10 times.

The grey area on the DMI graph shows the maximum and minimum values in the historical record for each day. The current event seems to be a record breaker, BUT for some reason DMI excludes the maximum and minimum value for each day, so perhaps not.

SMB loss has happened for a second day (see next post) and is higher. There is no doubt that 2 days of easily noticeable SMB loss at this time of year is very unusual. If it continues for a third day I think it classifies as an event.

click image to enlarge

gerontocrat · « **Reply #40 on:** May 02, 2021, 10:35:40 AM »

On this day the 1st May, a repeat of the 30th April, i.e.

Very low (almost zero) precipitation
less sublimation
less melt
= SMB loss for the 2nd time this season and very early indeed.

click images to enlarge

gerontocrat · « **Reply #41 on:** May 02, 2021, 10:46:50 AM »

SMB loss might continue for the next 2 to 3 days.

Daytime temperatures on the coast warm enough for melt.
Almost no precipitation (which helps sublimation?)

Now that would make an event.

gerontocrat · « **Reply #42 on:** May 03, 2021, 11:01:12 AM »

On this day the 2nd May, a repeat of the 30th April and 1st May, i.e.

Very low (almost zero) precipitation
minus sublimation
minus melt
= SMB loss for the 3rd time this season and on successive days and even greater.

Of interest is that although melt was a bit lower than the previous 2 days, SMB loss was higher. For why? Sublimation. The daily SMB map shows impressive sublimation. A really good demo of how sublimation can apparently make up to 10% of SMB loss during the melting season.

The GFS forecasts predict almost zero precipitation for the next 3 days (again), but temperatures not quite so conducive to melt. Will this event continue?

click images to enlarge

Stephan · « **Reply #43 on:** May 03, 2021, 01:23:07 PM »

A beautiful clear day at Freya Gletscher, East Grønland.
Freshly fallen snow on the rocks in the foreground has disappeared in two days. Melting? Sublimation?

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

gerontocrat · « **Reply #44 on:** May 03, 2021, 01:43:00 PM »

Quote from: Stephan on May 03, 2021, 01:23:07 PM

A beautiful clear day at Freya Gletscher, East Grønland.
Freshly fallen snow on the rocks in the foreground has disappeared in two days. Melting? Sublimation?

A nice simple article explaining conditions required for sublimation that even I can understand...

https://www.usgs.gov/special-topic/water-science-school/science/sublimation-and-water-cycle?qt-science_center_objects=0#qt-science_center_objects

Dry air. YES
Sunshine for heat. YES.
A wind rather like the Chinook.

With a high over central Greenland it looks like very dry winds cascaded down to both the West coast and part of the East coast.

Also looks like more of this for the next 3 days at least.

paolo · « **Reply #45 on:** May 03, 2021, 10:35:56 PM »

Quote from: gerontocrat on May 03, 2021, 11:01:12 AM

...
Of interest is that although melt was a bit lower than the previous 2 days, SMB loss was higher. For why? Sublimation. The daily SMB map shows impressive sublimation. A really good demo of how sublimation can apparently make up to 10% of SMB loss during the melting season.
...

The analysis is correct, but I would like to add a nuance, the information related to melt concerns the impacted area (% area) and not the quantity (GT). Clearly there is a link between the two pieces of information, but there is not a linear relationship between the two (for example, with the same extension and even with the same temperatures, we can have different amounts of melt depending on the wind speed).

Indeed it is a pity that for the melt we only have, to my knowledge, a measure relative to the extension...

paolo · « **Reply #46 on:** May 03, 2021, 11:04:38 PM »

I wanted to take a closer look at what happened at the Freya Glacier and I made an animation from 29/04 to 03/05. In particular I wanted to see if there wasn't, at least in part, an effect of the warming of the sun-exposed rocks.
Clearly there was snow between 29/04 and 30/04, followed by three sunny days, not a cloud in the sky, but chilly (with midday temperatures ranging from -3.2 to -2.1).
And if you look closely, especially if you enlarge the image to 100%, you can see that it's not only the snow around the rocky outcrops, but that the whole left side of the ridge ~~crinal~~ is literally deflating, it's breathtaking!
Even if the wind may have helped, it is obvious that there was a lot of sublimation.
One mystery remains, the disappearance of the snow on the shadow side, no sun, no sublimation!

PS: I added for beauty, an animation with the images of the second camera (but misses the image of 01/05)

Click to animate and click a second time to enlarge100% the images (2592x1728)

Stephan · « **Reply #47 on:** May 04, 2021, 08:40:16 AM »

There may be some sunny minutes or hours on the "shadow side" of the ridge earlier in the morning or later in the afternoon, of course with a lower sun's angle and therefore less insolation, even more reduced by the nothward falling slope. Unfortunately the webcams at Freya Gletscher only produce one photo per day, at noon time.

paolo · « **Reply #48 on:** May 04, 2021, 10:10:52 AM »

No, the shaded slope faces north and this time of year it cannot receive sunlight in the afternoon (let alone in the morning, being west of the main ridge above it, on which the camera is located).
The explanation must be :
1) in the wind which must have allowed a very limited deposit of snow on 29/30
2) in the fact that a minimal sublimation must be possible, even without sun, the necessary heat being taken from the air (~~air~~ the air being dry and renewed by the wind action)

P-maker · « **Reply #49 on:** May 04, 2021, 10:55:04 AM »

Paolo,

Sorry to interrupt, but you are simply not correct. After we passed the NH Spring Equinox about six weeks ago, the sun is now rising in the NE quadrant and settling in the NW quadrant. Thus, dry morning sun and warm evening sun will hit the north facing slopes in the Freya valley.

News:

Author Topic: Greenland 2020-21 SMB, melting and GRACE mass (Read 61116 times)