Week 3

02:43 GMT
64 49' S
60 26' W
-1.6 C
7 knot winds
clear sky mirror-smooth water
mix of open water and icebergs of all shapes and sizes

We saw the sun for the first time in quite a while this afternoon. Everyone made a trip out on deck or to the bridge to soak in the view and some sun. Winds were light, and temps were just below freezing, so being outside was fairly comfortable.

As you can see from the lat/long data, we have left the Larsen B area and begun our return trip north. We are currently headed into the Larsen A area, an area we worked in during May 2000. On that cruise, we had a low temperature of -23 C.  Quite a difference from the conditions we have now. We will be collecting samples from a few sites in this area and deploying a sediment trap in front of the Drygalski Glacier to monitor the influx of sediment from the glacier into the basin.

Setting sun reflects off icebergs in the Larsen A embayment in this view to the southwest towards the Drygalski Glacier. High peaks and plateau in the background rise to between 5-7000 feet above sea level.

23:19 GMT
64 47' S
60 23' W
-0.5 C
9 knot winds
developing overcast with low clouds on the mountains
smooth water with a mix of small and large icebergs

The sun rose this morning through a heavy fog over the ocean, lighting the faces of the high peaks and plateaus that lie just off our position.  By 10 a.m., the fog had burned off, and brilliant blue sky and spectacular view greeted the day shift as they headed to work and beckoned the night shift to skip lunch (their dinner).

As I mentioned in the last post, we have left the Larsen B area and are currently in the Larsen A embayment. Unlike the last time we were here (May 2000), the ice conditions have allowed us to penetrate virtually to the shoreline. The station we occupied this morning was less than a half mile off shore, but we were working in over 700 meters of water. Talk about sea floor relief!

This area is right where the Drygalski Glacier empties into the Weddell Sea. In the past, this massive valley glacier fed into the Larsen A ice shelf. Now it flows  and calves directly into the Weddell Sea. One of the concerns following the breakup of the ice shelf is the effect that the breakup will have on the valley glaciers that fed the system. The breakup of the ice shelf will not, by itself, cause sea level rise. If you fill a glass with ice cubes and then fill it to the brim with water, the glass will not overflow as the ice melts because the ice is displacing the same volume as ice as it will occupy when it melts. The ice shelf itself is floating, and the majority of it is below the water, displacing an equal volume. The valley glaciers are another story. These are land based glaciers, and any ice input into the sea will increase the sea volume. When the iceshelf was present, it acted to slow the advance of these glaciers. Now that it is no longer present, we are seeing evidence of increasingly rapid flow of the valley glaciers in the Larsen A & B areas, supporting published observations by Pedro Skvarca, and hence increasing input of land based ice into the Weddell Sea.

Deployment of sediment traps for future recovery and evaluation of kasten core sediments are some of the methods we are using to get a handle on the influx of sediment into the system as a proxy for increasing ice input from the valley glaciers that once fed the ice sheets in both the Larsen A and B areas.

These studies complement the sediment flux studies we have been doing over the past 15 years in the fjords on the western side of the peninsula.

The spectacular scenery is fantastic but as Bruce Huber commented, it can be distracting when you are trying to accomplish a task.

News reports we are getting say that the northeast is getting a major snowstorm, so enjoy these warm sunny images from the Antarctic.

-commentary provided by Dave Tewksbury, geology technician at Hamilton College

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