The melt extent algorithm used by Greenland Ice Sheet Today has been overestimating the melt extent, and as a result, daily images posted on this site in February and March may have indicated melt where none occurred.
This makes you wonder what other kinds of issues remain undetected in the satellite data. NSIDC has had to issue corrections in the past, when it was pointed out that their data and reality didn’t match. – Anthony
The algorithm for the Greenland Ice Sheet Today daily melt extent has been revised to account for unusually warm winter snow layers and residual meltwater deep in the snow. Meltwater from last summer’s intense melt season did not completely re-freeze through at least mid December. The adjusted algorithm shows greatly reduced melt extent for early 2013. This much lower extent is more consistent with available weather and climate records.
Melt extent and distribution
Figure 1. These images show cumulative melt extent before the algorithm correction (left) and after the correction (right). A few areas indicating one to two days of melting in southeast Greenland remain in the revised map. The red dot shows the location of the Danish AWS. Credit: National Snow and Ice Data Center – Click for hires imageAs shown in Figure 1, the adjustment to the algorithm resulted in fewer melt days than previously indicated. The revised image at right shows new surface melting in 2013 in a few small areas along the central southeastern Greenland coast, within the region of earlier spurious melt signals but greatly reduced.
Conditions in context
Figure 2. This image shows air temperature anomaly for Greenland for the period December 2012 to February 2013. Reds and oranges indicate higher than average air temperatures. The temperatures shown are at approximately 1,500 meters (5,000 feet) in altitude, appropriate for coastal Greenland regions. However, central Greenland is above this altitude, and values shown there do not represent the true surface conditions well. Credit: National Snow and Ice Data Center courtesy NOAA ESRL Physical Sciences DivisionTemperatures in Greenland have been higher than average this winter, with air temperatures near the coast averaging 2.0 to 3.5 degrees Celsius (4 to 6 degrees Fahrenheit) warmer than the 1981 to 2010 average. This has in part been a result of the persistent circulation pattern for the Arctic this winter, characterized by a negative Arctic Oscillation (AO). The AO is a measure of the intensity of the general pattern of low pressure over the northern high latitudes. A negative AO indicates higher-than-average pressures near the North Pole, allowing more frequent southward cold air outbreaks, and more intrusions of warm air masses from higher temperature areas. Despite these anomalously high temperatures along the Greenland coast, temperatures were not high enough to result in melting.
Adjusted algorithm and melt images
Figure 3. This plot shows surface air temperature at a PROMICE on-ice Automated Weather Station (AWS) near the southeastern Greenland ice sheet edge for early 2013. Temperatures did not exceed freezing at this site. Data from PROMICE were provided by the Geological Survey of Denmark and Greenland (GEUS) and are freely available. Credit: National Snow and Ice Data Center and J. Box, Geological Survey of Denmark and GreenlandThe melt extent algorithm used by Greenland Ice Sheet Today has been overestimating the melt extent, and as a result, daily images posted on this site in February and March may have indicated melt where none occurred. While the algorithm was indicating some coastal melt in February and early March, a comparison with weather data for Nuuk (the Greenland capital city, located along the southwest of the island) and data from the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) suggested these might be spurious melt readings. The local Automated Weather Station (AWS) data from a glacier along the southeastern coast (the Mittivakkat glacier AWS, shown by a red dot in Figure 1; data in Figure 3) indicate that the air temperature did not rise to the melting point (0 degrees Celsius, or 32 degrees Fahrenheit) in February or early March.
Figure 4. A model of the snowpack conditions indicates residual liquid water in the deep snowpack in southeastern Greenland. Credit: National Snow and Ice Data Center and X. Fettweis, Université de Liège, BelgiumDuring this period, starting around mid-February in southeast Greenland, the brightness temperatures in the upper few meters of the snowpack were 2 to 10 degrees Celsius (4 to 18 degrees Fahrenheit) higher than those observed during any other year in the 34-year record (1979 to 2012). While surface melt is not unprecedented in Greenland near the coast in February and March, the totals posted prior to March 14 were a result of these unusual snow temperature conditions, and not ongoing surface melt. This winter has seen unusually warm snow at depth on the ice sheet, following the intense melting that occurred last summer.
The melt detection method, based on passive microwave emissions, is primarily sensitive to near-surface conditions, but has some input from the snowpack down several meters (10 to 20 feet). Heavy snow fell during the relatively warm winter, burying and insulating deeper snow. This contributed to anomalously high temperatures for the uppermost layers of snow this winter. Additionally, models based on snowpack properties suggested that some 2012 meltwater remained unfrozen at 5 meters depth (approximately 16 feet) in mid-December. The model results are consistent with observations from JAXA’s AMSR-2 sensor.
The algorithm was adjusted by combining the trend of observed brightness temperatures with a model of the expected microwave emission in the channels used for melt detection (the SSM/I sensor’s 37 GHz Horizontal polarization channel). This adjustment is generally performed every year in March to calibrate the melt detection thresholds. However, because of the unusual condition of the snowpack, the adjustment needed to be made much earlier than ever before.
Further information
Fettweis, X., M. Tedesco, M. van den Broeke, and J. Ettema, 2011. Melting trends over the Greenland ice sheet (1958-2009) from spaceborne microwave data and regional climate models. The Cryosphere 5, 359-375, doi: 10.5194/tc-5-359-2011.
I believe if you changed all the catastrophic man-made global warming rhetoric, to a reference of the worldwide economy, rather than a reference to worldwide climate, the alarmists would be 100 percent accurate.
Niff
March 21, 2013 10:41 pm
So the images are…..photoshopped?
Lawrie Ayres
March 21, 2013 10:49 pm
It would appear the knowledge that an increasingly large number of climateers outside the government paid circle are keeping a careful and expert eye on their “data” is having a very positive effect. Shoddy work erring on the side of the warmers is no longer acceptable and is quickly identified and, encouragingly, is now being corrected. Kudos to all you honest scientists.
Lank remembers
March 21, 2013 11:20 pm
The Washington Post
“The Arctic Ocean is warming up, icebergs are growing scarcer and in some places the seals are finding the water too hot, according to a report to the Commerce Department yesterday from Consulafft, at Bergen, Norway
Reports from fishermen, seal hunters, and explorers all point to a radical change in climate conditions and hitherto unheard-of temperatures in the Arctic zone. Exploration expeditions report that scarcely any ice has been met as far north as 81 degrees 29 minutes.
Soundings to a depth of 3,100 meters showed the gulf stream still very warm. Great masses of ice have been replaced by moraines of earth and stones, the report continued, while at many points well known glaciers have entirely disappeared.
Very few seals and no white fish are found in the eastern Arctic, while vast shoals of herring and smelts which have never before ventured so far north, are being encountered in the old seal fishing grounds. Within a few years it is predicted that due to the ice melt the sea will rise and make most coastal cities uninhabitable.”
* * * * * * * * *
I apologize, I neglected to mention that this report was from November 2, 1922, as reported by the AP and published in The Washington Post – 90 years ago.
Yep – ice melt was a tad overestimated back then too – and without the help of satellites!!
Pingo
March 21, 2013 11:20 pm
Now try to spot a watermelon saying what good news this is! More difficult than finding an unbroken hockey stick..
Algorithms and models, not the reality, are über alles in the so-called climate science.
tty
March 22, 2013 12:08 am
One wonders why they didn’t check the weather at Kulusuk instead. Kulusuk is right in the middle of the supposed snowmelt area while Nuuk 400 is miles away on the other side of the icecap (and weather is often very different on the east and west coasts).
Here is weather for Kulusuk airport: http://www.tutiempo.net/en/Climate/Kulusuk_Lufthavn/02-2013/43610.htm
February: average temperature – 3,6, average maximum -1,1, average minimum -6,4, all Celsius.
Nine days with maximum above freezing, none with minimum above freezing, seventeen days with snowfall. Which means that there was certainly some daytime snowmelt, but that except for evaporation it refroze next night.
Rational Db8
March 22, 2013 12:26 am
@ur momisugly Lank remembers says: March 21, 2013 at 11:20 pm
Great post! Thanks for reminding us.
Gary Hladik
March 22, 2013 12:32 am
As with other areas of science, the devil really is in the details. Kudos for catching this error, now find the remaining bugs (yes, there are more).
Rational Db8
March 22, 2013 12:33 am
If Greenland is loosing all this ice over the past 30+ years, I’d dearly love to know how they explain the Glacier Girl.
For those here who might be unfamiliar, it’s easy to find the story online, and it’s truly fascinating. Essentially back during WWII, a small squadron of fighter planes had to ditch on Greenland. On the glaciers. About 50 years later, they went back and dug down through about 268 feet of ice to get to one of the P-38 fighters. They took her apart down in the hole, lifted her out piece by piece, Then they moved her to a more conducive location, put her back together and flew her.
Soooooo, to the researchers and scientists who think there’s been so much global warming causing huge ice melts…. just how the heck did a plane on the surface wind up buried under 268 ft. of snow and ice accumulated over those 50 years, during which so much of this global warming occurred????!!
stan stendera
March 22, 2013 12:54 am
Here we go again. Greenland ice melt over stated. Another body blow to the warmist’s creed.
David, UK
March 22, 2013 1:25 am
O.T., but in other news, heavy snow has fallen overnight throughout much of the UK, and continues to fall – and fall FAST. It’s a winter wonderland outside my window right now – and we’re three weeks into March! But I know it must be an illusion, because these days children just don’t know what snow is, because it NEVER snows these days. Yep, I’ll be wearing my shorts and Hawaiian shirt as is befitting for these warmer times.
DavidS
March 22, 2013 1:32 am
Meanwhile in the UK spring of 2013, children still don’t know what snow looks like.
sarc
SØREN BUNDGAARD
March 22, 2013 1:50 am
Al Gore-rithm issue;)
richard verney
March 22, 2013 2:20 am
Yet another example of a data set not fit for purpose.
Once again, the ‘error’ operating in the AWG proponents’ favour.
Guess, no surprise there. I share the sentiments expressed by Lawrie Ayres (March 21, 2013 at 10:49 pm) that being held up to scrutiny on the web is having some positive effect.
JDN
March 22, 2013 2:22 am
I remember commenting on a WUWT story a few years ago that someone needs to do spot checks on sea ice “data” from overflights. Is that going on? I look at the variation in sea ice coverage between algorithms, and the difficulty of figuring out what is ice vs. not ice, and I wonder how long until we find out that the Barents sea isn’t quite as ice-free as sea ice satellites make them to be.
Speaking of seeing things, I ran across the Dogger Bank incident (http://en.wikipedia.org/wiki/Dogger_Bank_incident) where the Russian navy destroyed British fishing boats because they thought they were Japanese. There was also a line in there about the American navy being so spooked by torpedoes that they fired at “ocean swells, trains on land, and rocks along the coastline, believing them to be enemy torpedo boats”. Just saying, it doesn’t require a computer to see things that aren’t there or vice versa, but computers help.
thomam
March 22, 2013 2:24 am
WIth the talk of all our “unseasonable” snow in the UK, I observe that it was my stepdaughter’s 15th burthday on Tuesday of this week and it has now snowed on 13 out of her 15 birthdays. But I suppose the plural of anecdote is not data…
Louis Hooffstetter
March 22, 2013 2:29 am
On March 22, 2013, the third day of spring, it’s literally freezing in the Carolinas. Yet somehow Greenland is melting!
Climastrology does it again!
tobias
March 22, 2013 2:48 am
I just won a bet here in BC Canada “against” a warmer (50 lat) , Lived here for 40 years bet him snow at least twice before March 19 ( It snowed 4 times.) Where does this report fit in anyhow, “Greenland ice melt overstated”,… in February ??. What else is new from their corner of the “debate”.
They are in full retreat , only theirs is real in contrast to the glaciers on Greenland.
Ian W
March 22, 2013 2:58 am
One would have thought that there would be some automated validation of these satellite metrics. There are numerous automated ground observation stations even in the arctic ocean there are automated buoys reporting weather and temperature data. There could be a rigorous cross check between the sensors that would have shown up inaccuracies very rapidly. Similarly for ocean temperatures now there are ARGO floats reporting SST they should be cross checked against satellite SST. As it is these ‘climate scientists’ take weather reports and rush off ito their pet politicians to trigger more non-science policies.
climatereason
Editor
March 22, 2013 3:07 am
Back in the days when I was naive i.e before I started to investigate the historic claims of climate change scientists-I would have believed the Greenland ice melt (and many other climate related things) was because someone had actually physically OBSERVED it. It seems that most climate science these days comes from models and maths and the original observed quality raw data is missing.
Incidentally, the warmest two consecutive decades in Greeland remain the 1930’s and 1940’s. We will have to wait until 2020 to see if the current spell of warmer than average weather beats it
tonyb
Dr. John M. Ware
March 22, 2013 3:13 am
Last year March here in Virginia was very warm, though not quite a record as I recall. This year is very different–cold, occasionally snowy, dreary. Two days ago it got to 62 degrees F here, the first day in the 60s this March, and likely the last according to the local weatherfellas. Yesterday our Weatherbug said the high was 46, but that was at midnight; by dawn it was 30 degrees, and by 7 a.m. it was 26 and snowing briskly. Not much stuck because the ground was so warm, but the grass and cars did get a white coating for a while. The high for the actual daylight was 35 with a brisk wind, making garden work impossible. How I have wished for just enough global warming to get some work done! Seeds need planting, beds need cleaning, etc., etc. Not in the outlook–more snow likely by Monday morning.
johnmarshall
March 22, 2013 3:23 am
Those damn temperature anomalies actually tell you nothing. It may be 3Cwarmer than a, supposed, average but was that above or below freezing, 0C?
The satellites also have problems with the many melt ponds that form on sea ice and report these as clear water. They also have problems with broken ice which again is reported as clear water.
Perhaps scare reports about the disappearing sea ice are not as real as thought.
So the Ice that was melting in Feb, was really not melting, and in fact might have been increasing in mass… Our Bad.
I believe if you changed all the catastrophic man-made global warming rhetoric, to a reference of the worldwide economy, rather than a reference to worldwide climate, the alarmists would be 100 percent accurate.
So the images are…..photoshopped?
It would appear the knowledge that an increasingly large number of climateers outside the government paid circle are keeping a careful and expert eye on their “data” is having a very positive effect. Shoddy work erring on the side of the warmers is no longer acceptable and is quickly identified and, encouragingly, is now being corrected. Kudos to all you honest scientists.
The Washington Post
“The Arctic Ocean is warming up, icebergs are growing scarcer and in some places the seals are finding the water too hot, according to a report to the Commerce Department yesterday from Consulafft, at Bergen, Norway
Reports from fishermen, seal hunters, and explorers all point to a radical change in climate conditions and hitherto unheard-of temperatures in the Arctic zone. Exploration expeditions report that scarcely any ice has been met as far north as 81 degrees 29 minutes.
Soundings to a depth of 3,100 meters showed the gulf stream still very warm. Great masses of ice have been replaced by moraines of earth and stones, the report continued, while at many points well known glaciers have entirely disappeared.
Very few seals and no white fish are found in the eastern Arctic, while vast shoals of herring and smelts which have never before ventured so far north, are being encountered in the old seal fishing grounds. Within a few years it is predicted that due to the ice melt the sea will rise and make most coastal cities uninhabitable.”
* * * * * * * * *
I apologize, I neglected to mention that this report was from November 2, 1922, as reported by the AP and published in The Washington Post – 90 years ago.
Yep – ice melt was a tad overestimated back then too – and without the help of satellites!!
Now try to spot a watermelon saying what good news this is! More difficult than finding an unbroken hockey stick..
Proof (if we needed it) that the “Unprecedented Greenland Ice Sheet Surface Melt” of 2012 didn’t really happen
http://www.nasa.gov/topics/earth/features/greenland-melt.html
Algorithms and models, not the reality, are über alles in the so-called climate science.
One wonders why they didn’t check the weather at Kulusuk instead. Kulusuk is right in the middle of the supposed snowmelt area while Nuuk 400 is miles away on the other side of the icecap (and weather is often very different on the east and west coasts).
Here is weather for Kulusuk airport:
http://www.tutiempo.net/en/Climate/Kulusuk_Lufthavn/02-2013/43610.htm
February: average temperature – 3,6, average maximum -1,1, average minimum -6,4, all Celsius.
Nine days with maximum above freezing, none with minimum above freezing, seventeen days with snowfall. Which means that there was certainly some daytime snowmelt, but that except for evaporation it refroze next night.
@ur momisugly Lank remembers says: March 21, 2013 at 11:20 pm
Great post! Thanks for reminding us.
As with other areas of science, the devil really is in the details. Kudos for catching this error, now find the remaining bugs (yes, there are more).
If Greenland is loosing all this ice over the past 30+ years, I’d dearly love to know how they explain the Glacier Girl.
For those here who might be unfamiliar, it’s easy to find the story online, and it’s truly fascinating. Essentially back during WWII, a small squadron of fighter planes had to ditch on Greenland. On the glaciers. About 50 years later, they went back and dug down through about 268 feet of ice to get to one of the P-38 fighters. They took her apart down in the hole, lifted her out piece by piece, Then they moved her to a more conducive location, put her back together and flew her.
Soooooo, to the researchers and scientists who think there’s been so much global warming causing huge ice melts…. just how the heck did a plane on the surface wind up buried under 268 ft. of snow and ice accumulated over those 50 years, during which so much of this global warming occurred????!!
Here we go again. Greenland ice melt over stated. Another body blow to the warmist’s creed.
O.T., but in other news, heavy snow has fallen overnight throughout much of the UK, and continues to fall – and fall FAST. It’s a winter wonderland outside my window right now – and we’re three weeks into March! But I know it must be an illusion, because these days children just don’t know what snow is, because it NEVER snows these days. Yep, I’ll be wearing my shorts and Hawaiian shirt as is befitting for these warmer times.
Meanwhile in the UK spring of 2013, children still don’t know what snow looks like.
sarc
Al Gore-rithm issue;)
Yet another example of a data set not fit for purpose.
Once again, the ‘error’ operating in the AWG proponents’ favour.
Guess, no surprise there. I share the sentiments expressed by Lawrie Ayres (March 21, 2013 at 10:49 pm) that being held up to scrutiny on the web is having some positive effect.
I remember commenting on a WUWT story a few years ago that someone needs to do spot checks on sea ice “data” from overflights. Is that going on? I look at the variation in sea ice coverage between algorithms, and the difficulty of figuring out what is ice vs. not ice, and I wonder how long until we find out that the Barents sea isn’t quite as ice-free as sea ice satellites make them to be.
Speaking of seeing things, I ran across the Dogger Bank incident (http://en.wikipedia.org/wiki/Dogger_Bank_incident) where the Russian navy destroyed British fishing boats because they thought they were Japanese. There was also a line in there about the American navy being so spooked by torpedoes that they fired at “ocean swells, trains on land, and rocks along the coastline, believing them to be enemy torpedo boats”. Just saying, it doesn’t require a computer to see things that aren’t there or vice versa, but computers help.
WIth the talk of all our “unseasonable” snow in the UK, I observe that it was my stepdaughter’s 15th burthday on Tuesday of this week and it has now snowed on 13 out of her 15 birthdays. But I suppose the plural of anecdote is not data…
On March 22, 2013, the third day of spring, it’s literally freezing in the Carolinas. Yet somehow Greenland is melting!
Climastrology does it again!
I just won a bet here in BC Canada “against” a warmer (50 lat) , Lived here for 40 years bet him snow at least twice before March 19 ( It snowed 4 times.) Where does this report fit in anyhow, “Greenland ice melt overstated”,… in February ??. What else is new from their corner of the “debate”.
They are in full retreat , only theirs is real in contrast to the glaciers on Greenland.
One would have thought that there would be some automated validation of these satellite metrics. There are numerous automated ground observation stations even in the arctic ocean there are automated buoys reporting weather and temperature data. There could be a rigorous cross check between the sensors that would have shown up inaccuracies very rapidly. Similarly for ocean temperatures now there are ARGO floats reporting SST they should be cross checked against satellite SST. As it is these ‘climate scientists’ take weather reports and rush off ito their pet politicians to trigger more non-science policies.
Back in the days when I was naive i.e before I started to investigate the historic claims of climate change scientists-I would have believed the Greenland ice melt (and many other climate related things) was because someone had actually physically OBSERVED it. It seems that most climate science these days comes from models and maths and the original observed quality raw data is missing.
Incidentally, the warmest two consecutive decades in Greeland remain the 1930’s and 1940’s. We will have to wait until 2020 to see if the current spell of warmer than average weather beats it
tonyb
Last year March here in Virginia was very warm, though not quite a record as I recall. This year is very different–cold, occasionally snowy, dreary. Two days ago it got to 62 degrees F here, the first day in the 60s this March, and likely the last according to the local weatherfellas. Yesterday our Weatherbug said the high was 46, but that was at midnight; by dawn it was 30 degrees, and by 7 a.m. it was 26 and snowing briskly. Not much stuck because the ground was so warm, but the grass and cars did get a white coating for a while. The high for the actual daylight was 35 with a brisk wind, making garden work impossible. How I have wished for just enough global warming to get some work done! Seeds need planting, beds need cleaning, etc., etc. Not in the outlook–more snow likely by Monday morning.
Those damn temperature anomalies actually tell you nothing. It may be 3Cwarmer than a, supposed, average but was that above or below freezing, 0C?
The satellites also have problems with the many melt ponds that form on sea ice and report these as clear water. They also have problems with broken ice which again is reported as clear water.
Perhaps scare reports about the disappearing sea ice are not as real as thought.