END OF SEASON FIELD REPORTS
2008-09 End of Season Field Reports
Investigation of Climate, Ice Dynamics and Biology using a Deep Ice Core from the West Antarctic Ice Sheet Ice Divide (I-477)
PI: Ken Taylor (Desert Research Institute)
|Tim Bartholomaus||Bess Koffman||Kendrick Taylor|
|Susan Lilja Buchardt||Logan Mitchell||Bruce Vaughn|
|Marie DelGrego||Anais Orsi||Gifford Wong|
|Natalie Kehrwald||Spruce Schoenemann||John Fegyveresi|
Field Season Overview:
We had an extremely successful field season. It got off to a rough start when budget cuts and problems with the camp's forklift delayed the science and drilling teams by two weeks. The science and drilling crews arrived at the very comfortable camp during the first week of December. It took another two weeks to set up the core handling and drilling equipment, train the crew, develop procedures, and conduct safety drills. We started around-the-clock operations with three shifts on December 22. Thirty-one days later, with only 4 rest days, we met our goal for the season, and then ran out of time and space to store the core.
Most of the season we were drilling brittle ice, in which the gas pressure in the ice is sufficient to spontaneously fracture the core when it is brought to the surface. We used several new methods to maximize the core quality. The resulting core quality is the best I have ever seen for brittle ice. By 1310 m the pressure was sufficient to push the air bubbles into clathrates and the ice was no longer brittle. Below this we pulled up clear unfractured 2.5 m pieces of ice.
Instead of the traditional approach of drilling and handling two meter long segments of brittle ice, we used a new drilling method. First, we drilled a one meter long piece of ice, and then pulled the drill up to snap the core off the bottom of the hole. Then, instead of bringing the drill back to the surface, we lowered the drill back down and drilled and snapped off a second one meter long piece of ice. Then we lowered the drill down a third time and drilled and snapped off a 0.5 m long piece of ice. Only after drilling 2.5 m, which is about the limit of the drill, did we bring the drill back to the surface. On alternate trips down the hole we would reverse the order so the 0.5 m long pieces would fill a single 1 m long core tray. This new drilling method allowed us to handle the core in 1 m long segments which reduced the size of the core handling and storage areas, provided higher quality core then would be obtained by cutting the brittle ice, and it allowed us to collect more core each trip down the hole.
Once the core was on the surface it was pushed out of the drill onto a carefully aligned and rigid support system. The careful alignment of this system using survey equipment was critical. The core passed through a new and more effective vacuum system for removing fluid from the core. The core was extruded into plastic netting, which held the core tightly together even after it had spontaneously fractured. To minimize the thermal shock to the core the core handling was done in an area that was refrigerated to a temperature of -30 C.
The combination of these new methods, breaking the core into the desired length while it was down hole and still under pressure, careful alignment of the core handling system, the netting, the low temperature in the core handling area, and a lot of really careful and focused people, all contributed to the high core quality.
None of this work came easily. On the drilling side of the arch, Jay Johnson and his crew spent tedious hours monitoring the drilling process on the control computers and making adjustments to the drill. Some of the adjustments were as small as 0.002 inches. You should think of the drill as a scientific instrument, not just a piece of drilling equipment. The drill crew had some down hole electrical problems, likely caused by just a few milliliters of ethanol that got in the hole as a result of deicing the drill. It was tricky but ICDS quickly figured out what was wrong and fixed it.
On the core handling side of the arch, NICL (Geoff Hargreaves and Brian Bencivengo) were diligent about establishing the core handling procedures. The core handling crew (mostly graduate students that were hired by the SCO) spent long hours in a noisy, windy, and cold environment doing the tedious job of documenting the core length and fractures. Anais Orsi and Bruce Vaughn organized lots of the details and filled in the occasional gaps.
Besides just collecting ice we also made science measurements. Natalie Kehrwald (hired by DRI but from OSU), John Fegyveresi (PSU) and Marie DelGrego (DRI) made electrical measurements on the ice cores. The measurements were made in the field instead of at NICL because the core quality is better in the field than at NICL. The measurements show strong well-resolved annual layers that will be used to determine the age of the ice. John also made vertical and horizontal thin sections of the ice below the brittle zone. Anais Orsi (Scripps) made borehole temperature measurements in a 300 m hole that will be used to help interpret the gas records. Bess Koffman (U-Maine) collected snow pit samples that will be used as part of the trace chemistry work.
The RPSC camp staff supported all of this work, lead by camp manger Ben Partan. There was a construction crew to set up camp at the beginning of the season, a crew to maintain the electrical, ventilation, cooling, and other systems at the arch, and another crew to do all the things typical of a small town (mechanics, communications, air craft transportation, waste disposal, cargo, medical, and of course food, really great food considering where we were). There was a big storm around Thanksgiving, then a month of gorgeous calm and clear skies. At the end of the season, when we were trying to move a lot of cargo and people, the weather closed in and we had the typical multi day waits for planes. No one likes to wait days for a plane, but as always, the 109th Air National Guard got our equipment and us in and out safely.
Along the way the entire camp crew pulled together into a tight community. Some of the highlights were the Christmas dinner and party, the New Years' Winter Olympics, a talent show, a traveling dance party held on a large and slow moving sled, and the occasional quite time with old and new friends. It takes a lot of personal effort and really positive attitudes to keep the energy high in a field camp, and this crew did that in style with seemingly endless ways to keep everyone engaged and in high sprits.
Many, many thanks to all those involved in the WAIS Divide activities this year especially, Matthew Kippenhan's planning management, Ben Partan's and Theresa Tran's camp management, Brian Johnson's and Cara Ferrier's science support, Sharon Lewis' cargo support, Julie Grundberg's and Sharon Lewis' fixed wing support, and Billy Texter's construction management. Special thanks to the WAIS Divide camp staff and the arch facility construction staff for all of their help and support this season. This project would not be possible without the dedication and continual support of Julie Palais, Brian Stone and George Blaisdell, our sincere thanks to them.