Greenland under early pressure too

When I posted that weather forecast for the Arctic in the Beaufort under early pressure blog post a few days ago and said very large anomalies are forecast for Greenland and Baffin Bay, it didn't really occur to me just how exceptional that temperature anomaly was going to be for Greenland and its ice sheet*. Now I know.

A bell started to ring softly today while reading this blog post by Robertscribbler, in which he describes the temperatures and wind speeds that hit Greenland yesterday. But things really hit home when I read this news article on Polar Portal, written by Dr. Ruth Mottram from the Danish Meteorological Institute:

Unusually Early Greenland Melt

An early melt event over the Greenland ice sheet occurred this week, smashing by a month the previous records of more than 10% of the ice sheet melting.**

Left: Maps showing areas where melting has taken place within the last two days. Right: The percentage of the total area of the ice where the melting occurred from January 1 until 11th May (in blue). The dark grey curve represents the 1990-2013 average. The grey shaded area represents the year to year variation for each day.

Based on observation-initialized weather model runs by DMI, almost 12% of the Greenland ice sheet had more than 1mm of melt on Monday 11th April, following an early start to melting the previous day. Scientists at DMI were at first incredulous due to the early date. “We had to check that our models were still working properly” said Peter Langen, a climate scientist at DMI. “Fortunately we could see from the PROMICE.dk stations on the ice sheet that it had been well above melting, even above 10 °C. This helped to explain the results”. The former top 3 earliest dates for a melt area larger than 10% were previously all in May (5th May 2010, 8th May 1990, 8th May 2006).

“Even weather stations quite high up on the ice sheet observed very high temperatures on Monday”, said Robert Fausto, a scientist at GEUS who maintains PROMICE.dk melt data. “At KAN_U for example, a site at 1840 m above sea level, we observed a maximum temperature of 3.1°C. This would be a warm day in July, never mind April”. Other PROMICE stations in the network at lower levels had daily average temperatures between 5 and 10 °C.

Daily mean temperatures at NUK_L (near Nuuk) and KAN_U (near Kangerlussuaq) for each day in 2016 (PROMICE.dk).

Similarly, around the coast of Greenland where DMI has climate records dating back to 1873, Greenland came close to setting a record temperature for the whole of Greenland in April. Kangerlussuaq measured a daily maximum of 17.8°C, the previous record is 18.0°C and the DMI observation station at the Summit of Greenland set a new “warm” April record of -6.6°C. “Everything is melting” observed Nuuk resident Aqqaluk Petersen.

Read the rest here.

Things are forecast to cool down again in the region in the next few days. We will have to wait and see if this unusual event is just a fluke, or a harbinger of things to come. Hopefully not, but it's been a crazy year so far.

---

* Of course, over on the Arctic Sea Ice Forum commenter S. Pansa already spotted this a week ago.

** It seems 2012 saw an even earlier and more widespread melting event, although I'm not sure if this NSIDC graph (found here) can be compared directly to the DMI graph:

We all know what happened in Greenland that year (this and then this)...

---

Addendum April 13th:

I've asked Ruth Mottram about the differences between the way DMI and NSIDC measure ice sheet melt as a percentage of total cover and here's her reply:

We have looked at the dates Marco mentioned and found they did not pass our (admittedly rather arbitrary) threshold of 10% of the ice sheet area melting though it came fairly close.

The 5^th and 6^th April 2012 both had about 9% of the area melting in our model, days either side had about 3% melt area.

To answer your question on the NSIDC and DMI Greenland melt products:

The two products are complimentary as the NSIDC method is essentially a satellite based estimate of where melt is occurring based on passive microwave scatter, whereas our SMB and melt estimates come from a model. The surface model is driven by a weather forecast model, which has observational data assimilated into it, but with no observations directly assimilated from the ice sheet surface. Nonetheless we are pretty confident it does a good job in describing the melt area as, when the NSIDC page is live, the two are often rather similar. The promice stations on the ice sheet also confirm that the HIRLAM/HIRHAM model performs pretty well in characterizing the ice sheet weather.

We hope to produce a paper showing this and documenting the model system soon.

Two further differences between the two products that may cause a divergence in results:

1)      We use different ice masks, ours is based on a very thorough mapping of the ice sheet carried out by Michele Citterio and Andreas Ahlstrøm at GEUS, the NSIDC one is older and in most places has a larger ice sheet area. I think it may be based on an old USGS map of Greenland as our previous ice mask had some similar problems. This would probably mean that the NSIDC product shows a larger melt area than the model.

2)      The resolution of the two data products is also different, our model is run at 5km, the NSIDC product calculates gridded brightness temperatures for grid cells of 25 x 25km. This means you may get a different percentage area of the ice sheet when comparing melt across grid cells.

It's too bad the NSIDC is experiencing a data gap due to problems with the SSM/I sensor aboard the DMSP F17 satellite, as we'd then have a second apple-to-apple comparison. And two apple-to-apple comparisons can be an interesting apple-to-orange comparison. But alas.

Comments

[D]

NSIDC is still "calibrating" for 2016. I looked for information there but found nothing. Thanks to you and DMI for writing up this chilling story.

[AbbottisGone]

What do you mean by still calibrating?

Is there some sort of official word on the matter?

The graphs went up,... Is this false?

[Neven]

Yes, there is an official word on the NSIDC website:

NSIDC has suspended daily sea ice extent updates until further notice, due to issues with the satellite data used to produce these images. The vertically polarized 37 GHz channel (37V) of the Special Sensor Microwave Imager and Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) F-17 satellite that provides passive microwave brightness temperatures is providing spurious data. The 37V channel is one of the inputs to the sea ice retrieval algorithms, so this is resulting in erroneous estimates of sea ice concentration and extent. The problem was initially seen in data for April 5 and all data since then are unreliable, so we have chosen to remove all of April from NSIDC’s archive.

It is unknown at this time if or when the problem with F-17 can be fixed. In the event that the sensor has permanently failed, NSIDC is working to transition to either the DMSP F-18 or possibly the JAXA Advanced Microwave Scanning Radiometer 2 (AMSR2) on the Global Change Observation Mission – Water (GCOM-W) satellite. Transitioning to a different satellite will require a careful calibration against the F-17 data to ensure consistency over the long-term time series. While this transition is of high priority, NSIDC has no firm timeline on when it will be able to resume providing the sea ice time series.

A switch to AMSR2 wouldn't bee too great, because if everyone starts to rely on that and it goes boom too...

Of course, there will always be other (non-passive microwave) sensors to observe Arctic sea ice, but changes should be kept as small as possible.

[Neven]

Robertscribbler has a follow-up post: The Greenland Summer Melt Season Just Started in April

And Climate Central reports: Greenland's Melt Season Started Nearly Two Months Early

[Neven]

I've asked Ruth Mottram about the differences between the way DMI and NSIDC measure ice sheet melt as a percentage of total cover and here's her reply:

We have looked at the dates Marco mentioned and found they did not pass our (admittedly rather arbitrary) threshold of 10% of the ice sheet area melting though it came fairly close.

The 5th and 6th April 2012 both had about 9% of the area melting in our model, days either side had about 3% melt area.

To answer your question on the NSIDC and DMI Greenland melt products:

The two products are complimentary as the NSIDC method is essentially a satellite based estimate of where melt is occurring based on passive microwave scatter, whereas our SMB and melt estimates come from a model. The surface model is driven by a weather forecast model, which has observational data assimilated into it, but with no observations directly assimilated from the ice sheet surface. Nonetheless we are pretty confident it does a good job in describing the melt area as, when the NSIDC page is live, the two are often rather similar. The promice stations on the ice sheet also confirm that the HIRLAM/HIRHAM model performs pretty well in characterizing the ice sheet weather.

We hope to produce a paper showing this and documenting the model system soon.

Two further differences between the two products that may cause a divergence in results:

1) We use different ice masks, ours is based on a very thorough mapping of the ice sheet carried out by Michele Citterio and Andreas Ahlstrøm at GEUS, the NSIDC one is older and in most places has a larger ice sheet area. I think it may be based on an old USGS map of Greenland as our previous ice mask had some similar problems. This would probably mean that the NSIDC product shows a larger melt area than the model.

2) The resolution of the two data products is also different, our model is run at 5km, the NSIDC product calculates gridded brightness temperatures for grid cells of 25 x 25km. This means you may get a different percentage area of the ice sheet when comparing melt across grid cells.

I'm adding this answer to the blog post.

[wayne]

The ice horizon announced this heat wave well before it arrived.
It was marked by a prolonged, longer than all previous records, continuous lower horizon.

It also goes like this, the coldest atmosphere agglomeration has shrunk dramatically dragging straight North Cyclones usually dedicated to the UK and Ireland.

The coldest air never garnished enough depth on land and sea ice,
so summer will come early everywhere.

[Bill Fothergill]

Whilst on the Woods Hole site looking for some info on Sea Level Rise, I happened to notice the attached article discussing Greenland melt.

https://www.whoi.edu/oceanus/feature/scientists-find-trigger-that-cracks-lakes

As he is excellent at sniffing out such pieces, it is very possible that Colorado Bob has already mentioned this article in an earlier thread. (It's a toss-up these days which is worse - my memory or my eyesight.)

[Colorado Bob]

Bill Fothergill -

Thanks for the hat tip.

(It's a toss-up these days which is worse - my memory or my eyesight.)

Move over, you're not the Lone Ranger.

Insert smiley face here.

[Colorado Bob]

Bill Fothergill -

I read about this today in Antarctica. Cracks appear in the ice . Melt water drains down the cracks , it wedges the ice apart.
It's called "hydraulic fracking" .
Scientists Are Watching in Horror as Ice Collapses

http://news.nationalgeographic.com/2016/04/160412-ice-sheet-collapse-antarctica-sea-level-rise/

[Colorado Bob]

Scientists Are Watching in Horror as Ice Collapses

http://news.nationalgeographic.com/2016/04/160412-ice-sheet-collapse-antarctica-sea-level-rise/

Water weights 8.6 pounds per gallon. It's very heavy.

It moves the heat. It carries life. It's 70 percent of life.

[Jeff Lemieux]

This is the article on Antarctica that's troubling me today. From an insurance conference of all things. Don't know if this is well vetted or just some more offhand comments, but the hints that the latest fieldwork is from WAIS is particularly bad, but that the results won't be released for years, is a bit jarring.

http://www.insurancejournal.com/news/national/2016/04/12/405089.htm

Margaret Davidson, NOAA’s senior advisor for coastal inundation and resilience science and services, and Michael Angelina, executive director of the Academy of Risk Management and Insurance, offered their take on climate change data in a conference session titled “Environmental Intelligence: Quantifying the Risks of Climate Change.”

Davidson said recent data that has been collected but has yet to be made official indicates sea levels could rise by roughly 3 meters or 9 feet by 2050-2060, far higher and quicker than current projections. Until now most projections have warned of seal level rise of up to 4 feet by 2100.

These new findings will likely be released in the latest sets of reports on climate change due out in the next few years.

“The latest field data out of West Antarctic is kind of an OMG thing,” she said.

[AbbottisGone]

Going out on a limb I would expect that forecasts of 3m of sea level rise by 2060 would never be released!

If that is anywhere near the truth we are already in anarchy!!

[Al Rodger]

Jeff Lemieux,
I think you would describe Margaret Davidson as a technical/scientific civil servant rather than a scientist and her un-referenced statement is not well made.

I'm sure that if there were some "OMG" field data out of West Antarctica, even preliminary data, it would not remain secret in the manner described. So I would suggest that Davidson is referring to something in plain sight.
Perhaps she refewrs to Hanson et al (2016). That paper is based on a certain level of evidence but is more a discussion document rather than a focused piece of science. It does point to "West Antarctica and Wilkes Basin in East Antarctica (having) potential to cause rapid sea level rise" which sort of fits the bill although the paper does not provide the "roughly 3 meters by 2050-2060".

[FrankD]

Are the F-17 sensor issues behind the bizarro numbers Cryosphere Today have been posting recently? Areal variations of 700,000 sq km per day can't possibly be right.
(obviously there are some data quality assurance issues as well, but that's another story...)

[Jim Hunt]

Frank - In brief - Yes! For much more detail on that see:

Satellite Problems With Arctic Sea Ice Measurement

For a related story on "data quality assurance issues" in certain sections of the cryoblogosphere see also:

Global Sea Ice “Comeback” Conspiracy

As you point out "that can't possibly be right", but certain "experts" seemed not to notice:

You will note that we were not the only ones to swiftly conclude that Judy [Curry]’s assertion was lacking both veracity and verisimilitude!

Do you suppose we can now expect a “fulsome apology” from the other players in this tragi-comic farce, together with all their rebloggers, retweeters, plagiarisers and other assorted acolytes?

[AbbottisGone]

I like to imagine the good people of NSIDC let the false data go on for few more days to imply that a concession from the deniers was really required once they admitted their data had to be admitted faulty and thus pulled from the official record.

I like to imagine...

[Jim Hunt]

Fondly imagine if you so desire AiG, but no hint of an apology, fulsome or otherwise, has yet emerged via the virtual pens of Curry, Peiser, Watts et al.

http://GreatWhiteCon.info/2016/04/global-sea-ice-comeback-conspiracy/#comment-214267

Watts seem particularly keen to prevent any hint of the actual facts emerging within his soundproof "skeptical" echo chamber.