Meteorological Controls on Snow Accumulation and Chemistry in the St. Elias Mountains and the Implications for Ice Core Research in Regions of High Relief
Meteorological Controls on Snow Accumulation and Chemistry in the St. Elias Mountains
This Project is supported by a generous grant from the Dan and Betty Churchill Exploration Fund
Nate Vogan July 6th to 24th, 2006
The Arctic plays a prominent role in global climate change research because of both its sensitivity to changing climate and because of the relative wealth of paleoenvironmental proxy records available. Proxy records developed through physical and chemical analyses of ice cores provide the highest resolution and most direct view of Earth?s paleoatmosphere over time scales ranging from single seasons to hundreds of thousands of years. Recent research efforts have focused on developing high resolution ice core records from the St. Elias Mountains in southwestern Yukon Territory and southeastern Alaska. During the summers of 2001 and 2002, scientists from the Geological Survey of Canada (GSC), National Institute for Polar Research in Tokyo, University of New Hampshire (UNH), and University of Maine (UMaine) recovered ice cores from three different glaciers in the St. Elias Mountains, southwestern Yukon Territory. On the Eclipse Icefield (∼30 km northeast of the Logan Massif) an UNH/UMaine team recovered a 345 m core along with three other shallower cores.
Previous work on an ice core recovered in 1980 from Mt. Logan (Holdsworth et al, 1991, Holdsworth and Krause, 2002) has shown that major discontinuities in the variation of the water stable isotope ratios with altitude, which are believed to be derived from a multilayered atmosphere during precipitation events on high altitude glacier sites. To properly interpret the glaciochemical records developed from the new St. Elias ice cores, calibration of snow properties with meteorological data (temperature, precipitation, and sea level pressure) is critical. At the Divide Site, two automatic weather stations (AWS) have been operating since 2002, collecting snow depth as well as standard meteorological data. Therefore, the timing of snow accumulation over the past 4 years is known precisely, providing a unique opportunity to investigate the atmospheric controls on snow deposition and chemistry in the St. Elias Mountains.
July 6th to 24th, 2006
Whitehorse, YT and Kluane Lake Research Station
|After a few minor travel snags and near mishaps along the way I arrived in Whitehorse, YT, at 12 am local time on July 8th. Being near the height of summer, night never really fell, rather just a prolonged twilight. The rest of the day was spent collecting the miscellaneous supplies for that would be necessary for completing my work up at the Divide site. The morning of the 9th I rendezvoused with the University of Ottawa glaciology field course participants led by Luke Copeland and Peter Johnson and caught a ride up the Alaskan highway to the Kluane Lake Research Center operated by the Arctic Institute of North America out of the University of Calgary. We arrived to driving rains and chilly temperatures. The one day delay in camp due to unsavory flying weather provided me with ample opportunity to make a final check of the field gear and round-up the necessary equipment to be flown up to the field site. The weather finally broke and I was able to reach the field site on the morning of the 11th.
|July 11-19: Divide Site
|I was the last to arrive at the Divide site and therefore had the benefit of having camp already set up for me by the Ottawa students. The first two days in the field were spent digging the first four meters of the proposed five meter deep snowpit to be sampled at 5 cm intervals for snow chemistry. With six undergrads helping, it was relatively light work allowing us to dig an impressive two meters a day without resorting to a narrow confined shaft. With the relative speed of our work I was able to complete my sampling of the days? digging during the late afternoon and early evening hours. This turned out to be important on July 12th when we received an evening snowstorm (our only inclement weather while on the icefield).
On the third day we trekked to the nunataks near our camp to download the meteorological data from a weather station there. On the way back I proceeded to return the favor of the digging provided by the Ottawa students by helping them in an exercise of ice depth sounding. The next two days were spent digging the final one meter and sampling of the snowpits, as well as digging down to the cooler containing the data logging equipment at the base of the snow depth sounder near camp. We spent the next two days charging the battery pack with a solar panel and attempting to download the data. After several unsuccessful tries we were forced to call in some help from Christian Zdanowicz of the Geological Survey of Canada, who was successful in downloading our data for us.
With the sampling complete and weather station data downloaded, we were then able to accomplish our final task of raising and securing the snow depth sounder weather station near camp. We were able to raise the sounder to 3.44 m above the current snow surface in anticipation of the accumulating snow over this upcoming winter. We then secured and sealed the cooler at the base of the pole. With the objectives of the field season we were free to spend the last day in camp hiking to the big nunatak 4 km from base camp. It was a spectacular climb with rewarding views of Mt. Logan and the surrounding glaciers.
|July 20-22: Kluane Lake Research Station
|After successfully completing my work at the Divide Site, it was nice to kick back and relax by the shores of Kluane Lake (Fig 4). We ended up getting lucky in flying down on the 19th in that the weather in the mountains took a turn for the worse and prevented flights for the next three days. In the mean time I was able to organize my gear for the long trip home, and was even given the opportunity to talk to a Canadian journalist doing a piece on climate change.
|The last few days in Whitehorse were really enjoyable in that I was free to do some of the sightseeing that I was unable to do while shopping for supplies on my only other day in town. Some of my highlights include the Beringia Musuem and some hiking on the bluffs above town which included getting within 10 ft of a bald eagle. The trip home was largely uneventful and the samples survived the repeated abuse of airline baggage handlers without any significant loss or contamination.