Canadian Arctic Experiment Includes LI-COR Gas Analyzers

Braving the cold, wind, ice and snow (and the occasional polar bear wandering into camp) is all in a day's work for Dr. Tim Papakyriakou, Assistant Professor of Geography at the University of Manitoba, and colleagues involved in the Collaborative Interdisciplinary Cryospheric Experiment (C-ICE), an evolution of sea ice projects dating back to the early 1990's, to provide previously unavailable data on the nature of the atmosphere - sea-ice - ocean interaction. As a part of this project, an eddy correlation tower that includes the LI-7500 Open Path CO2/H2O analyzer, a CSAT-3 Sonic Anemometer (Campbell Scientific, Inc., Logan, UT), and other instrumentation was deployed in May and June, 2002, in Resolute Bay, Nunavut (formerly Northwest Territories) in the Canadian Arctic (Figure 2).

One of the objectives of Dr. Papakyriakou's project is to measure the CO2 fluxes over sea ice, to determine if there is an atmospheric/oceanic coupling in the presence of ice. According to Dr. Papakyriakou, no previous measurements of this type have been made over ice in the Arctic, or in polar regions in general.

The instrument tower shown in Figure 1 was mounted over first year ice (ice that freezes and thaws annually) of about 1.5 m in thickness. 10-15 cm of melt water covers this ice during melt, making the tower accessible only by snowmobile over much of June and July. According to Dr. Papakyriakou, the LI-7500 was "the obvious choice" for this project, because of its open path, fast response for both CO2 and H2O channels, low power consumption, all-weather capability, and low operating temperature (to -40 °C) range.

In addition to the surface eddy flux measurements, a unique technique using a powered parachute (paraglider) to fly transects over the study area provided an intermediate test bed for improving remote sensing technology. An instrument package (developed by Dr. David Barber, also at the University of Manitoba) secured to the underside of the seat provides information on surface characteristics (reflectance, temperature, video) for a scaling exercise to tie surface processes and morphology.

CO2 and H2O fluxes collected from this remote measurement site are currently being evaluated; preliminary indications are that there are strong diurnal and seasonal signals corresponding to the CO2 partial pressure in the upper ocean, and that CO2 fluxes over 1.3-1.5 m thick ice may approach that seen over open ocean.

This preliminary work being done by Dr. Papakyriakou and colleagues is in preparation for a large multinational project, the Canadian Arctic Shelf Exchange Study (CASES), which started in the fall of 2002. For the CASES project, more than 130 principal scientists from 12 countries will look at the mechanisms whereby carbon is exchanged between rich productive arctic shelves and deep ocean basins. In September of this year, a one-year experiment will begin by over-wintering a class-1200 Canadian Coast Guard icebreaker in the study area. The bow of the ship will be fitted with instrumentation, including the LI-7500; a land-based tower with a second LI-7500 will support year-round sampling of the shelf's atmosphere.

At first opportunity, after overwintering in sea ice, the icebreaker will travel to polar ice regions free of ice called polynyas. These regions are of significant biological importance, as a variety of life forms congregate at these polynyas. Breaking out of the ice and traveling to the polynyas will allow researchers to study them just as they are opening, as well as chart their distribution as the climate changes.

Studying the arctic shelf/carbon cycle exchange with the deep ocean has global significance, for a number of reasons; 1) the water is cold, and can hold a lot of dissolved carbon, 2) the waters are nutrient rich and prone to algal blooms in spring and summer months, and 3) the shelves are a zone where "bottom water" is formed. On the fringes of the arctic shelves, where ice is forming, brine is expelled from the ice, so that the underside of the ice has a higher salinity. The water here "sinks" due to higher salinity. As a result, carbon can be sequestered at the bottom of the sea bed, or held for long periods of time, until it circulates into warmer regions and is expelled.

The CASES project should help answer the key question of variation of carbon flux with time and space over the annual cycle in this arctic environment.

LI-COR is proud to be a small part of this important work. For more information on how the LI-7500 can help with your research, contact LI-COR or a LI-COR representative, or click here.

Thanks to Dr. Tim Papakyriakou, Assistant Professor, Geography, University of Manitoba, for contributions to this article, and to Dr. M. Fortier for the polar bear photo.