Archive for August, 2013

Visiting and monitoring South Greenland dark ice

Friday, August 16th, 2013

I’m spending a week flying out of Narsarsuaq, south Greenland, with colleague Dr. Robert Fausto, to maintain climate stations equipped to monitor surface ice melt in great detail. Part of the Danish PROMICE network, the stations obtain surface energy and mass budget closure. The closure means that calculated melt matches with observed melt.

coming in to land at a PROMICE climate station, one of 22 on Greenland ice operated by GEUSPhoto J. Box.

Flying across this vast space and on the ground, I’m is struck by how abundant snow algae and other light absorbing impurities can be. The low reflectivity impurities amplify the effects of the increasing melt season. Increased melt means a shorter duration of highly reflective snow cover. The prolonged exposure of an impurity-rich bare ice surface multiplies melt rates. I’ve calculated that without this albedo feedback, the increase in melt rates would amount to half of what’s observed. Some of this feedback is due to ice crystal rounding. Some is due to the impurities. Measuring the relative importance of metamorphic and impurity driven albedo reduction is a subject of our work.

boots on the ice offer a close look (and to sample) impurities concentrating at the surface. The fact is, much of this dark material is from cyanobacteria and blue-green algae. Photo J. Box.

puddles often form with this kind of algal slick’. Photo J. Box.

It’s exciting to be working with Dr. Marek Stibal who studies the microbial environment on Arctic ice. Together with his data, the surface energy exchange data from the PROMICE climate stations and Danish Meteorological Institute’s regional climate modeling (Follow @Greenlandsmb), we have a powerful approach to unravel more detail from the melt story in Greenland.

South Greenland Dark Ice. Photo J. Box.

Snow accumulates in crevasses forming snow bridges that one would rather fly over. In between, impurity-rich ice absorbs up to 80% of the Sun’s energy. Photo J. Box.

Surface melt water mingles with impurity rich Greenland ice. Photo J. Box.

Robert Fausto maintains a climate station equipped to measure downward and upward solar energy, among many other climate parameters as part of the Danish PROMICE network (Follow @PromiceGL). Photo J. Box. (Follow @Climate_Ice)

Greenland 2013 melt is over the hill

Monday, August 12th, 2013

While average sea ice minimum occurs in September, the Greenland ice albedo minimum occurs in July. This year, the albedo minimum occurred 31 July, coinciding with a record setting warm episode.

By 9 August, fresh snowfall concentrated along the southeastern ice sheet brought up the ice sheet albedo.

Across the northwestern ice sheet, melting increased the first 10 days of August, darkening the surface from a brighter than normal pattern associated with abnormally large snow accumulation that made difficult the Japanese SIGMA expedition.

Ice sheet albedo remains anomalously low along the western upper ablation area. The most persistent low albedo this melt season has been along the northwest, in the vicinity of Storstrømmen glacier.

Heat transport into the Arctic bypassed Greenland to it’s east. Svalbard has had a warm summer.

A reliable feature of climate is the poleward transport of heat in the atmosphere (and ocean) and the main contuit into the Arctic is the North Atlantic. So, what we see in this figure is normal and Greenland just didn’t get much exposure to this warm air stream (marked with up-pointing purple arrows). This extra heat bypassed Greenland much of this summer.

Greenland high near-surface air temperature record set

Saturday, August 3rd, 2013

It’s worth adding that the large scale circulation, if (likely) delivering (excess, anthropogenic) heat and moisture via south air advection, is arguably a legitimate part of a climate change narrative. The foehn effect may not be an aside if atmospheric humidity were increased by climate warming, yielding additional latent heat release in the downslope compression of the foehn effect…

Greenland soars to its highest temperature ever recorded, almost 80 degrees F.

By Jason Samenow, Published: August 1 at 1:47 pmE-mail the writer

 

The Danish Meteorological Institute is reporting that on Tuesday, July 30, the mercury rose to 25.9 C (78.6 F) at a station in Greenland, the highest temperature measured in the Arctic country since records began in 1958.

The balmy reading was logged at the observing station Maniitsoq / Sugar Loaf, which is on Greenland’s southwest coast, the DMI reports. It exceeded the 25.5 C (77.9 F) reading taken at  Kangerlussuaq on July 27, 1990, in the same general area. Mantiitsoq is Greenland’s sixth-largest town, with a 2010 population of 2,784.

4880007af6Weather pattern responsible for record warmth in southwest Greenland (Danish Meteorological Institute)

The DMI says the record warmth was brought about by southeasterly winds, funneled by the flow between a large area of high pressure over continental Greenland, and low pressure over Baffin Island to the west.

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.

Via the Danish Meteorological Institute: "Satellite photo of the area around Maniitsoq and Sugar Loaf Mountain on Tuesday 30 July 2013. Photo from NASA's Terra satellite."Via the Danish Meteorological Institute: “Satellite photo of the area around Maniitsoq and Sugar Loaf Mountain on Tuesday 30 July 2013. Photo from NASA’s Terra satellite.”
(IPCC)Conceptual model of how a warming baseline climate increases the chance of record-breaking weather (IPCC)

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.”

Related, from 2012: Greenland ice sheet surface melt: massive meltdown or meaningless trickle?

This warm temperature extreme in Greenland comes on the heels of an astonishing heat wave in northern Siberia.

Wunderground weather historian Christopher Burt described a “perhaps unprecedented” streak of 10 days in the central Arctic region of Russia in which temperatures exceeded 86 degrees F (30 C) in mid-to-late July.

Prior to this, it was the desert southwest reaching heat milestones.  Recall Death Valley set the record for hottest U.S. temperature ever recorded in June, climbing to a blistering 129 degrees.

At the moment, China is in the midst of a record-breaking heat wave.  And in Alaska,Fairbanks and Anchorage have ongoing historically long streaks of warm weather.

These heat events were all likely set up predominantly by the configuration of naturally varying weather patterns.  But  elevated greenhouse gas concentrations may well be tacking on a small warming contribution, nudging these extreme events into record territory.

Jason Samenow is the Capital Weather Gang’s chief meteorologist and serves as the Washington Post’s Weather Editor. He earned BA and MS degrees in atmospheric science from the University of Virginia and University of Wisconsin-Madison.