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