UPDATE: 7/12/13 1045 PDT DMI concedes the record may not be valid, see here
I’ve been working on this one for a week, and I finally confirmed my hunch about where the weather station is located. The story begins with Jason Samenow at the Washington Post, who made a big deal out of a new temperature record in Maniitsoq, Greenland:
Any time I read about new record temperatures in the Arctic or Antarctic, I tend to think of this simple truth: In near polar settlements, temperature is measured close to that small human island of warmth , and since most such towns are completely dependent on aviation, the measurement is often done at the airport, since weather there is a go/no go factor of primary importance.
It turns out I was correct. What was surprising was just how correct my hunch turned out to be.
First, the Maniitsoq, Greenland data for July 30th, courtesy of Weather Underground:
Note the yellow highlights for the Tmax. This confirms Samenow’s story, though I find it curious that Weather Underground didn’t round up to 79F based on Samenow’s reported value of 78.6F (which he likes to say is nearly 80F). No matter, there are other issues that I was suspicious of.
First, this is a weather event, it doesn’t have anything to do with climate, as DMI indicated on their weather map for the day, strong warm winds behind a warm front washed over southwest Greenland, where Maniitsoq is located:
Weather pattern responsible for record warmth in southwest Greenland (Danish Meteorological Institute)
Samenow was correct in noting:
It adds the warmth may have been enhanced by a phenomenon known as the Foehn Effect, in which air flows over nearby elevated terrain and compresses and heats on its way down. In this case, DMI believes the air may have passed over the elevated Sugar Loaf ice cap and then dried and warmed up as it descended (or downsloped) on its leeward side into Maniitsoq.
But then falls back into the “it must somehow be related to global warming” position saying:
The DMI says the warmth was not “unnatural”, but explains it fits into a long-term pattern of climate warming.
“[T]here is an indisputable gradual increase in temperature in Greenland,” DMI writes. “Along the way, any ‘warm event’ thus have a higher probability of being slightly warmer than the previous one.”
As I pointed out at the beginning of this article, the temperature was measured at the airport. But how good is that weather station location? Is it biased by its placement at the airport? It took me a week to find it, but find it I did.
First, an overview from Google Earth of the town and the airport. You can clearly see the “nearby elevated terrain” near the airport.
The winds were out of the Northeast at the time of the high reading after 5PM, note yellow highlights:
Next, from aerial closeup and my experience with spotting hundreds of weather stations for the SurfaceStations project, this is where I thought the Stevenson Screen might be at the airport. try as I might though, I couldn’t find a photo of it.
It turned out that a video shot by a tourist (Bart Rietveld) confirmed my suspicion, I found it this morning during a bout of insomnia. Here’s the screencap from the video, looking Northwest from the tarmac at BGMQ aka Maniitsoq airport.
Source: @ 0:15 into this video:
Here is what I conclude about the station placement:
- Maniitsoq airport is a recent development in the history of the area, it has been settled for almost 4000 years. It is an anomaly carved out of the landscape (see first Google Earth image).
- The weather station is surrounded by the airport runway and tarmac, which is unnatural ground cover. Note how dark it is in the tourist video.
- The dark albedo there is enough to melt snow in the winter, in fact they count on it to help keep the airport open. Just like I showed in Svalbard, they have to keep the runway open even after snowfall, and it becomes an albedo anomaly surrounded by snow.
- The local siting effects likely added to the temperature record on July 30th because the easterly wind would also have picked up some of the heat from the terminal building and tarmac and transported it to the weather station.
- For these reasons, it isn’t a good place to measure temperature for climate, but it is the best place to measure weather/temperature for aviation purposes: right next to the runway.
It seems that DMI agrees that this temperature is artificially elevated at the Maniitsoq airport, because according to this story in Nunatsiaq Online, DMI has discarded the record in favor of one in the town. They added this footnote to their story about record heat in Greenland:
[Note: the DMI later rescinded the claim that the July 30 temperature was a record-breaker, saying that the lower temperature recorded at another station in the community — 24 C — stands for that day. That’s 1.9 C lower than the record, which is still to be broken]
Note also that DMI had this to say in the original report on the event:
Whether the 25.9 ° C later elevated to a new record for Greenland will first be decided after further climatological study of the situation.
While I could not find the rescinding announcement at DMI, likely due to me being unable to effectively interpret the language on the DMI website, I can confirm that as of today, 11 days after the event, the old record still stands:
It looks like Mr. Samenow at the Washington Post will need to issue a retraction. Ditto for Dr. Jason Box and who also bought into the event without questioning it or following up on it.
And these news articles need corrections (readers can help by sending notes to them):
- Greenland soars to its highest temperature ever recorded, almost 80 degrees F. (washingtonpost.com)
- Greenland Hits Highest Temperature Ever Recorded (thesterlingroad.com)
- Global weirding 2013: same temp in Ojai as in Greenland (achangeinthewind.com)
- Record high temperature recorded in Greenland (summitcountyvoice.com)
- Greenland hottest ever (blogs.redding.com)
- Greenland experiences ‘record high’ temperatures (blueandgreentomorrow.com)
UPDATE Dr. Richard Keen adds in comments:
All this discussion of a degree or two is a moot point, since even the “nearly 80 degrees”, i.e. 79F, is still 7 degrees short of the record high for Greenland.
That honor belongs to Ivigtut, down on the southern tip of Greenland (probably not far from Maniitsoq), where it was 86F (30.1C) sometime before 1940. This record is published in:
Climates of the World, in Climate and Man – Yearbook of Agriculture, US Dept of Agriculture, 1941
Climates of the World, US Dept. Commerce, 1969
and even in Wikipedia: http://en.wikipedia.org/wiki/Ivittuut
So you know it’s valid.
I don’t know the exact date of the record, but suffice it to say it’s before 1940, which explains why the DMI chose to use records starting in 1958. After all, Greenland weather records go back to 1784 (Vinther et al., Extending Greenland temperature records into the late eighteenth century, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D11105, doi:10.1029/2005JD006810, 2006). It’s a common ploy for the Warmers to act as though climate started in 1958, when Keeling starting recording CO2 on Mauna Loa, or 1947, when the PDO went cool, or 1970, when Arctic temperatures bottomed out, to get their upward trends.