Base de données de recherche des TNO

étiquettes: physical sciences, glaciology, sea ice

Objectif(s): To provide information on the thickness distribution, movement, and characteristics of different types of sea ice within the Beaufort Sea Region.

Description du projet: The objective of this study is to provide information on the thickness distribution, movement, and characteristics of different types of sea ice within the Beaufort Sea Region. The focus will be on hummocked multi-year sea ice referred to as Extreme Ice Features (EIFs). These EIFs are poorly understood, and would be the most hazardous to any engineered structure in the southern Beaufort Sea (such as for off-shore resource development). The research program will include on-ice measurements of sea ice thickness and characteristics, deployment of buoys, as well as sea-ice measurements from an electromagnetic induction (EMI) system mounted on an aircraft. The plan is to conduct a 2-week sampling program of the multi-year sea ice on the west side of Banks Island in from April 4 to 19. During this time, the plan is to sample up to 7 floes of multi-year ice (extreme ice features). The on-ice team will consist of 5 people (4 researchers and a wildlife monitor). On ice work will occur from April 4-13, while aerial surveys will occur from April 11-19. This research methodology falls into several categories: Buoys – Three different types of buoys will be deployed on the multi-year sea ice. • Position-only buoys - Approximately 15-20 of these will be deployed to investigate sea ice movement. Suitable ice (large, thick floes) is located with a helicopter or plane. The research team plans to use two kinds of position-only buoys: 1) manually-deployed buoys – the helicopter or plane lands on the ice and researchers turn the buoy on; and 2) air-deployable buoys – these are deployed from aircraft. • Ice mass balance buoys – Two ice tethered buoys will be deployed to gather data on the surface meteorology (air temperature, wind speed and direction), sea ice temperature (0-10m), and characteristics of the water column’s upper 50 m (temperature/salinity). A current meter will collect ocean current data under the ice for the duration of the field program, and then will be retrieved. • GPS buoys – Precision GPS buoys will be deployed while we are on the ice to measure ice motion at centimeter scales. The research team will relate ice motion to local winds and oceans currents, and regional scale motions based on measurements obtained from satellite observations (RADARSAT-2). Snow and ice characteristics – On-ice sampling will include measuring the thickness of multi-year ice along transects by drilling 2” holes through the thickness of the ice. 10-40 holes will be drilled at each sampled ice floe. Depth profiles of ice will also be conducted from ice core collection. A 6” diameter, motor powered ice corer will be used to obtain ice cores up to 12 m long, from which the ice salinity and temperature will be measured. A borehole indentor will be used to measure the strength of the multi-year ice to a maximum depth of 12 m (year 2 only). Electromagnetic Induction Surveys • Aerial surveys – To quantify the thickness and regional distribution of multiyear ice and extreme ice features in the southern Beaufort Sea, large-scale airborne surveys for ice thickness will be conducted. Airborne electromagnetic surveys over thick multiyear ice have not been extensively validated. By combining the airborne surveys with drill-hole data obtained on collocated ice floes and extreme ice features, the team will validate and improve thickness retrievals from the airborne surveys. The researchers will also be obtaining drill-hole data. • On-ice surveys – For smaller scale measurements of snow and ice thickness, the team plans to use a sled-based EMI system. This piece of equipment is pulled across the sea ice surface on foot and will supplement ice and snow measurements obtained using the 2 inch augers. • Community Based on-ice surveys. The same EMI system used to measure the extreme ice features during the 2-week field program, will also be used as part of the Community-Based Monitoring Program. Based on input from the community, location(s) for these surveys will be chosen close to the community. The intention here is to measure local ice thickness from winter into the spring melt period along the same transect(s). This system will be towed by snowmobile. Physical ice thickness measurements will be made to compliment the EMI surveys as well as CTD (Conductivity, Temperature and Depth) measurements to record the changing sea temperature and salinity profile of the water. These plans will be discussed in detail with the community members as part of the planning process. Community representatives are invited to contribute to the planning of airborne campaigns, by pointing out regions of interest where data should be preferentially gathered to be of most interest for the Beaufort Regional Environmental Assessment (BREA) community. Community representative are invited to participate in Electromagnetic Induction (EMI) survey flights to perform wildlife observations or their own assessment of ice conditions. They are also invited to bring their own equipment (e.g. cameras) to mount on the aircraft. The latter has to be discussed as soon as possible if of interest. As part of the research project, the research team plans to have a community-based monitoring program. This would entail locals from the community of Sachs Harbour measuring sea ice thickness by towing a piece of equipment called an EM sled (about 20 pounds) behind a snowmobile in certain areas. The equipment automatically records ice-thickness and saves it electronically. There will also be a need for drilling holes in the ice to take several measurements in support of the ice-thickness sled, as well as downloading data. These surveys would be conducted on a weekly basis from April to June. Training would be provided in the community for those who would be conducting the surveys. Project activities and results will be reported through the BREA Program, which will in turn communicate this to communities through community visits. Project participants will participate in BREA coordinated consultations events and supply the necessary information to ensure locals are fully aware of planned project activities and research results. Several representatives attended and presented in Inuvik during a BREA-led consultation in December of 2011 with participants from each of the ISR communities. Results will also be distributed through science journals, poster and oral presentations at science conferences and workshops, as well as through the publication of graduate student’s theses. Web-based public online reports will also be made available from the researchers associated with the National Research Council – Canadian Hydraulics Centre (http://chc.nrc-cnrc.gc.ca). Communication to the public will be done through media requests and interviews. A flyer presenting a project overview will be created and distributed to the local communities. The fieldwork for this study will be conducted from April 5, 2012 to April 19, 2012.