West Antarctica: 1998-1999 season

There were two main projects during this field season, both run out of the Siple Dome field camp.

The first project was the 1st re-survey of the three "coffee-can" sites on Ice Stream D. We were flown to each site via Twin Otter aircraft, after which we set up camp for approximately two days in order to: (1) re-survey the markers at each site using precision GPS; (2) obtain a hand drilled, shallow firn core (see "1997-1998 season for pictures") and (3) survey the local topography with kinematic GPS. Shallow cores are obtained at each site in order to obtain a measurement of the accumulation rate of the last ~40 years. This is possible because nuclear weapons testing in the late 1950's left a residue of radioactive fallout over the ice sheets. This layer can be detected by sensitive instruments during laboratory processing, meaning it can be used as a time horizon within each core. This allows us to determine how much snow has accumulated at a location since the time the fallout horizon was deposited. The local topography is surveyed so that its effect on the downward motion of markers within the firn can be removed.

The second project was a velocity survey of ~30 locations on the ice plain (lightly grounded region) between Ice Stream B and the Ross Ice Shelf into which it flows. All of these sites were surveyed a decade or so ago. Other research has indicated that the ice in this region is slowing down by ~20% per year, and this re-survey would allow for a comparison of precise velocity measurements with a large time interval in between the re-survey's. This turned out to be a rather hectic project, as bad weather on the ice shelf was persistent for much of the beginning of the field season. More or less, all of the work was done over several very long days where we flew to the various sites and to and from Siple Dome on a near non-stop basis. The Twin Otter flight crews switched out after a day/nights work, but we did not. We did however, manage to get all of the sites re-surveyed. That project is still being worked on, but the general results substantiate the observed slow-down of ice flowing into this region.

Only a few of the photo's here are field work related as there was generally not much interesting to take pictures of. We did have a unique opportunity to visit the deep ice coring operation at Siple Dome, which hit bedrock while we were in camp, and there are some photos related to that. As with the '99-'00 field season, we were able to go for a cruise on the coastgaurd icebreaker at the end of the season, and there are a few photos included from that trip as well.

For more photos related to "coffee-can" field work, see photos at the '97-'98 and '96-'97 season links.