Friday, September 8, 2017

Glacier Bird on BBC


The final episode of BBC TWO's new documentary series about mountains will air at 9 pm on 13 September, featuring a variety of sequences filmed in the Andes.

Among the Andes sequences will be a segment filmed at Quelccaya, as described above. Several wonderful "behind the scenes" clips have been produced for the Glacier Bird film, one of which is here (hopefully available soon in North America). A link to the page above, with an embedded clip, is here.

Since the time of filming - just last year - science has moved forward:  we have discovered a second species of bird which also nests on the glacier (Hardy et al., submitted to Wilson Journal of Ornithology), and Glacier Bird's taxonomic classification has changed from Diuca speculifera to Idiopsar speculifer. The common name in English remains White-winged Diuca-Finch, but this too may change because the bird is not a Diuca-Finch!

For those not in the UK, the series will be broadcast in North America by PBS at a later date.

Tuesday, August 29, 2017

"Mountain: Life At The Extreme" (new BBC series)


On Wednesday evenings at 9 pm starting 30 August, television network BBC TWO will be airing a new 3-part documentary series exploring three different mountain ranges: the Rockies, the Himalaya and the Andes.

Each episode is more than a natural history program in that it depicts examples of both the "extraordinary animals and remarkable people" living in these extreme environments (quote credit here).

The Rocky Mountain
sequences feature wolverines, extreme skier Hilaree O'Neill, big horn sheep, and Native American horse racing - among others. Clips and more are available on their website:  <http://www.bbc.co.uk/programmes/b093x4gb>

The Himalaya episode also features
animals, along with the people comprising remarkable ancient cultures. One exciting sequence follows Nepali ultrarunner Mira Rai through a race. (Mira is featured in the May 2017 issue of Outside Magazine, and will be running one of the UTMB races in Chamonix this week.) For more on the episode, including clips and updated information, check the BBC website: <http://www.bbc.co.uk/programmes/b094klt5>

Details on the final episode airing 13 September have not yet being released. This post will be updated when they are - for it includes a sequence on our work at Quelccaya.

Unfortunately for North Americans, BBC TWO is not available. There will be rebroadcasts by PBS, but dates are not yet available.

Tuesday, August 15, 2017

dry-season weather


We visited Quelccaya for fieldwork during July this year and experienced a long interval of sunny, dry weather. Although July is solidly within the core winter dry season, the atmosphere was particularly dry at this time; the cloud visible in the background above was literally the largest we saw during our time at the ice cap.

Below are two oblique views of the glacier margin, on the day that we arrived in the area (20 July) and the day we departed (27 July). Due to funding constraints, this was a relatively short trip. After 8 days of clear sky and intense solar radiation, some might expect to see more change in the transient snowline than the images show. In other years of fieldwork this has certainly been the case. This year, the areas of greatest apparent change over the interval are highlighted by the red ellipses. Although these areas were determined subjectively from the images, rather than measurements of snow depth, two clear-sky satellite images roughly bracketing the period reveal a similar pattern (see below).

Why so little ablation of snow, within a zone which is both thinning and retreating rapidly in recent decades? Most likely, this was due to the combination of dry atmosphere and low wind speed during this interval. With a negative vapor pressure gradient due to the dry air, any available energy went toward sublimation, requiring ~8 times more energy per kilogram than melting. Furthermore, low wind speed suppressed turbulent transfer of latent heat. At the summit, relative humidity was typically ~10 percent (vapor pressure <2 hPa) and rarely rising to 50 percent during the afternoons.

Despite little ablation during this brief interval of the dry season, recession of the ice cap in this area is accelerating. A subsequent post and paper will quantify retreat we have been measuring since 2008, revealing the profound changes associated with the 2015-16 El Niño event.





Monday, June 19, 2017

dry season begins?


Beautiful clear weather at Quelccaya at the end of last week. The transient snowline appears to be rising, as evidenced by the darker areas of bare ice around the ice cap margins. Note that some snow still exists on high ridges around Quelccaya.

Great products coming from the European Space Agency (ESA) these days, and planned for the future. Hopefully NASA Earth observation will begin receiving more support and recognition, after the U.S. 2018 mid-term elections!

Monday, May 15, 2017

2016-17 accumulation [updated]



The current accumulation season began ~8 months ago, almost immediately after a Landsat image was acquired on 16 September. Last year was thus an atypical situation in which the ELA can be known with some confidence, which for 2016 was ~5600 m.

Excepting the first half of November, accumulation steadily increased into early April. Although the rate of accumulation then decreased, telemetry reveals that snowfall continues, as illustrated by the image above - depicting the area yesterday through high clouds. Note that fresh snow is visible on the landscape even at elevations below the glaciers. Since the mid-September minimum, 2.05 m of snow has accumulated at the AWS.

[UPDATE 06/01:  Two weeks later, snowcover on Quelccaya and the surrounding landscape shows little change, on a Landsat 8 image acquired on 30 May. Quite a contrast to last year, following reduced accumulation during the 2015-16 El Niño.]

Thursday, November 10, 2016

Accumulation begins for 2016-17


New accumulation is underway at Quelccaya. The image above depicts the ice cap and surrounding terrain on 3 November, thanks to NASA & USGS! Contrast snowcover on the ice cap last week with that shown below on 16 September.

Telemetry of snowfall measurements from the Quelccaya AWS shows that about 6 cm of additional ablation occurred in the week following when the image below was acquired. Between then and 3 November (see above), the AWS recorded 32 cm of snow accumulation - which very likely indicates that the next wet season is underway. So, although net accumulation for the 2015-16 El Niño will be much below average, it appears that the event will indeed be recorded at the summit. This may not have been the case if the wet season began later, as is more typically the case.

Thursday, October 6, 2016

Snowline continues rising


The transient snowline at Quelccaya reached ~5600 m in mid-September, as illustrated on the Landsat 8 image above. Had the wet season begun by then, only the upper ~100 m of the ice cap would have seen net accumulation for the El Niño year 2016. However, it is likely that ablation continued after the time of this image.

A subsequent Landsat image was acquired on 2 October. New snowcover is visible south of Quelccaya, but cloud cover obscures the ice cap. So, we must wait for the next few satellite passes to see whether the snowline continues rising - or if the new wet season has begun. The first opportunity for this assessment will be in ~10 days.

This situation demonstrates a difficulty of mapping minimum snowcover extent from satellites. Thin high clouds (as in this image) or scattered cumulus clouds still allow snowcover assessment, yet cloud cover thick enough to obscure the ground prevents mapping. As a result, the spatial extent of accumulation cannot be accurately determined by remote sensing some years.