Tuesday, July 12, 2016

Taku Glacier and the Juneau Icefield Research Program

Last week we finished some of the last work on Taku Glacier under our current NSF grant. We serviced all our borehole instruments that we installed last year; many of which are still working. We also ran a low frequency radar to measure the ice thickness. In the past, Taku had been excavating sediments at its base, so the glacier has been getting thicker, although the surface elevation barely changed. In some places this happened at rates of more than 3 m/yr!

Taku Glacier is an advancing glacier, but over the past two years it has been retreating slightly. This is probably still an after-effect of the very warm winter 2014/15, when no snow fell on the lower glacier. Consequently, last summer saw a big seasonal retreat, and this winter's advance could not compensate for that. It will be interesting what happens after this El Nino is over.

After Taku, I was invited to go to JIRP (Juneau Icefield Research Program) and give a lecture. This is an undergraduate research expedition that has been going on every year since the 1940s. I was very impressed by the program and the many smart and interested students, many of which had very little or no experience with snow and ice.

Doug is laying out radar antennas

Ice radar in crevassed areas
Nice evening light at our base camp

Base camp at sunset

JIRP Camp 17 at the top of Lemon Creek Glacier

The JIRP students are doing safety training on the glaciers. For some it was their first time on skis.

JIRPers at sunset





Sunday, June 19, 2016

The 4th International Glaciological Summer School in McCarthy

We're just back from an International Summer School that we organize every other year. 28 graduate students from all over the world came to McCarthy, Alaska, to hear lectures about glaciology, show their research to peers and work on projects. We also did two glacier hikes, and many took the opportunity to see this fantastic landscape from the air.
This is the fourth time we did this, and this was the luckiest we've been with weather: all but one day were blue sky with amazing views of the Kennicott Glacier and the phenomenal Stairway Icefall.

The Root Glacier with the amazing Stairway Icefall.

Mike Loso is explaining the local glaciology to the summer school students
A river on the glacier

 

Inside a glacier cave.

Tuesday, June 14, 2016

The Tyndall tsunami

In October 2015, a large rockfall was released near the terminus of Tyndall Glacier in Icy Bay.
The rockfall grazed over the lower part of the glacier and then fell into the ocean creating one of the largest tsunamis ever recorded. At its highest point, the wave reached about 180 m a.s.l.!

The break-out area is to the left of the glacier. It scraped off the surface of the lower part of the glacier

The wave cleared the entire shore line of trees.

The trees are all pointing into the fjord implying that it was the outgoing wave that caused most of the destruction.

The tsunami destruction is clearly visible along the entire side of the fjord.


Saturday, May 21, 2016

Surging glaciers everywhere

The glaciers in the Kluane National Park, right across the border from Alaska are particularly active this year and we have been able to observe several of them. Glacier surges are spectacular. When they occur the glacier can move at up to one hundred times its normal speed and in the process most of the glacier surface becomes extremely crevassed and distorted beyond recognition. Below are some pictures. Unfortunately, they didn't turn out very sharp through the airplane windows.

The Steel Glacier is undergoing the most vigorous surge:

On the upper glacier, the ice surface has dropped be several tens of meters, leaving behind a "bathtub ring" of stranded ice.

The fast flow creates very crevassed shear margins






The Walsh Glacier is also surging. I think it's in its third year of surging now, but this is by far the most active I've seen it:





And finally a picture of Fisher Glacier. This surge might be done; it reached all the way to the glacier front.


Monday, May 16, 2016

Operation IceBridge: The Stikine Ice Field

One of the most amazing things I get to do as a glaciologist is to help survey many or Alaska's glaciers from the air, as part of NASA's Operation IceBridge. This spring we have a big program and we started at the very southern end of the state: The Stikine Ice Field. Below are some impressions.

We based our flights out of Petersburg, Alaska; one of the most picturesque places in the state. In the background, the ice field with its most prominent mountain, the Devil's Thumb, is recognizable.

 
The best-known glacier of the ice field is LeConte Glacier, the southernmost tidewater glacier in the northern hemisphere:

 
Adjacent to LeConte Glacier is Baird Glacier. Until last year, it was a land-terminating glacier. But then a big subglacial flood floated the terminus and now the glacier ends in a lake. It looks like it might be retreating for a while.

 The flood on the Baird came out of a weirdly amazing place: The Witche's Cauldron. It's in the picture below, the area in front of Devil's Thumb. A big subglacial lake forms in the cauldron and then catastrophically releases along the Baird Glacier.

On the way home we passed the Juneau Ice Field. Here is a nice shot of the Hole-In-The-Wall Glacier (on the right) and Taku Glacier (on the left). Both are advancing glaciers. The Hole-In-The-Wall Glacier didn't even exist 150 years ago, it only formed when the Taku Glacier readvanced and spilled over.

And, finally, here is our science platform. The Single Otter, piloted by famous bush pilot Paul Claus

Tuesday, April 19, 2016

Our annual Black Rapids trip

Every year in spring we fly to Black Rapids to keep maintaining a mass balance program that goes back to 1973, but that has no longer any funding support. It comes in handy to have a plane on skis! We try to do the measurements in early April, a time when interior Alaska is often blessed with stable and nice weather. We managed to find such a day last week.


Sunday, April 3, 2016

Taku Glacier seismic survey

This is the last year of our Taku Glacier study. One of the major goals was to repeat a seismic study. We drilled almost 100 holes and filled the with explosives. The resulting seismic waves were recorded on a long string of geophones and this will help us characterize the nature of the sediment underneath the glacier.

I was a bit apprehensive heading to Taku after last year's rainy field season, but it turned out fine. There was some snow on the glacier; not a lot, but enough to work with. We did have some rain, but also several sunny days and some snow. At some times rain, snow, and sunshine occurred simultaneously, in typical Southeast Alaska fashion.

On the flight out we had a nice view of the glacier, which is still advancing pretty healthily.

My colleague Andy Aschwanden took some really nice pictures: https://www.flickr.com/photos/ak64north/albums/72157666219362885

The camp on a sunny evening



Ice advancing onto the 'Oozy Flats'


Ice overriding trees at the glacier front

This section of the Norris River was blocked by the glacier last year, but not quite this time