Monday, June 2, 2014

Yakutat: a glaciologist's paradise

Yakutat, Alaska, is a small town on the coast. The area around this little town hosts some incredible mountains and glaciers, some of them among the most rapidly retreating in the world, others quite happily advancing. Here are some impressions from our recent flights.

Turner Glacier seems to surge about every 2-3 years. It repeats surges more rapidly than any other glacier I know of. The surges are very violent, and nothing on the glacier remains uncrevassed.

Turner Glacier: the surge advances a front right into the ocean. It is one of the few (if not the only) surging tidewater glacier in Alaska.

Hubbard Glacier is an anomaly in this area: it has been steadily advancing during the past more than 100 years

Strong tidal currents manage to keep this gap open for now.
Hubbard Glacier threatens to close off this gap at Gilbert Point.

Looking out Yakutat Glacier into Harlequin Lake. The glacier has retreated dramatically in the past few years. It might have accelerated in the process, at least it looks much more crevassed than a few years ago

The glacier has separated into two different glaciers recently. The ice in the lake has already broken off and will soon flush out

Tuesday, May 27, 2014

Glacier Bay and the Fairweather mountains

The Fairweather range in Southeast Alaska must surely be among the most spectacular mountain ranges in the world. Mt. Fairweather rises from the Gulf of Alaska to over 4000 m over a distance of only about 20 km and then it drops right back to sea level on its east side towards Glacier Bay (Google maps). The area is heavily glaciated with big glaciers dropping from the peaks to the ocean. The spectacular topography is a result of the very active tectonics of the area with the giant strike/slip Fairweather Fault cutting right along the coast.

Mt. Fairweather. The Fairweather Fault runs along the long straight valley. Alsek Lake is in the foreground

Alsek Glacier and Alsek Lake

Mt. Fairweather with sand beaches in the foreground

Chris and Austin are putting up a GPS base station

Entrance to Lituya Bay. This narrow opening has treacherous tidal currents that have cost many lives, including some members of the first European visitors to the area under La Perouse.

LaPerouse Glacier is the only glacier in Alaska that reaches the outer coast. It has not changed much, in contrast to many glaciers around it. Sometimes, like in this picture, it is separated from ocean by a narrow beach, but sometimes it calves directly into the ocean.

The Glacier Bay altimetry program is quite extensive, and cannot be flown in a single day. So we camped at the beach.

LaPerouse Glacier

LaPerouse Glacier descends very steeply towards the ocean

An advancing glacier in Lituya Bay. This glacier has separated itself from tidewater and is no longer losing mass through calving. As long as it maintains sediments in front of it, it is able to advance.

Lituya Bay. An earthquake in 1958 caused a rockfall into the bay, which caused the biggest recorded wave in history. It reached up to 500 m above sea level. The scar can still be seen on the right side of the image. The lighter vegetation marks the area that was stripped by the wave.

Melbern Glacier and Lake

Monday, May 26, 2014

Airborne glacier science

For almost two decades the glaciology group has measured glacier surface elevations in Alaska with a laser flown on (relatively) small aircraft. Originally this was done with a small two-seater piper PA-12, but for the last decade or so from a much more powerful Single Otter turbine aircraft, operated by Paul Claus of Ultima Thule Outfitters. These measurements form the basis of glacier change assessments in the Alaska, the Yukon and much of British Colombia, some of the most rapidly changing areas of the world. Chris Larsen has been in charge of this program for many years, and this year I had the chance to be part of it and deploy a radar to measure ice thickness. The beauty of this program is that you can only fly in the mountains when the weather is good. So we get to see some of the most amazing mountains on Earth during this work. Below are some impressions from this May. I'll put up a few more posts from the different areas we visited.

The Ultima Thule Lodge, from where we base our operations

Frozen glacier lake

Terminus of Logan Glacier

Hanging ice in the St.Elias mountains

Ocean waves reflecting off the shore

Snow runnels. They are common, but I don't know what causes them

Lenticular clouds forming: it's windy!

Tuesday, April 22, 2014

Annual Black Rapids trip

This was a quick three-day trip to Black Rapids to get all instruments ready for the summer. Just as last year, it was quite windy on the glacier and the slopes were so wind-loaded that I didn't dare going there to put up the cameras that we use to watch lake drainages.
The snow pack was quite unusual: Near the glacier terminus, there was no snow. It had all melted in an extreme warm event this winter. But the upper glacier had a record snow pack. This came right after the most ice loss there in 40 years of measurements.

Camp in the Lokket tributary

Nice view of Hayes from the Richardson Highway

The night we cam back there was a lunar eclipse. Here it is just starting (over the Tanana River)

Almost at full eclipse

Wednesday, April 9, 2014

Taku Glacier

We just started a new project on the Taku Glacier. The goal is to take a closer look at glacier erosion. This glacier is amazing. In previous work we have found that it can excavate as much as 3 m of sediment per year. That is, the glacier is primarily growing at the bottom, by digging itself into soft sediments. Over the next three years we will take a detailed look at how this works. Last week we used radar and seismics to map the glacier bed. With a detailed seismic survey we hope to also find the depth of the sediments under the ice. Next year we will drill through the glacier to find out how it moves over its substrate.

Here are some pictures from this year's field work:

The Juneau Icefield

View from the camp site: Split Thumb

The tent camp

Alessio working on the seismic line on a windy day

The camp with the ocean in the background. If Taku kept advancing, it would eventually cut off the Taku River and create a huge lake. This has happened in the historic past, but the warming climate is unlikely to sustain the current advance for much longer.

The first days were quite windy with lots of blowing snow

The first wiggles show the return of seismic waves from the glacier bed

Orion on a clear night

At the moment, Taku Glacier is still advancing

Roman inspects the sediment bulges in front of the advancing ice

A tree is no match for advancing ice

Ice advancing over sediment

And the yellow bird that's taking us home again.