Base de données de recherche des TNO

Régions: Inuvialuit Settlement Region, Gwich'in Settlement Area

étiquettes: physical sciences, sea ice, ice thickness, snow depth

Objectif(s): To obtain measurements of sea ice properties during the annual maximum sea ice extent.

Description du projet: Fundamental sea ice properties such as volume and surface characteristics change significantly within and between years. Arctic sea ice extent and thickness have undergone dramatic changes in the past decades. The strength of ice-albedo feedback mechanism depends on area-averaged ice concentration, snow and ice thickness and in summer significantly on melt pond fraction. The sea ice retreat in Arctic summer leads to formation of more first-year ice, which usually shows a larger melt pond fraction compared to multiyear ice. Hence, the area-averaged albedo decreases and the thinning of the ice cover accelerates. The goal is to obtain crucial measurements of sea ice properties during the annual maximum sea ice extent in March/April and minimum sea ice extent in August/September. The observations are organised as a repeating series of field campaigns to assess ongoing changes and to support predictions of the Arctic sea ice cover. The main observation target is the distribution of sea ice thickness on regional scales as well as ice surface properties such as snow cover in spring and melt pond coverage in the summer month. The general inaccessibility of the Arctic Ocean and its marginal seas require the use of polar research aircraft to implement a meaningful sea-ice observation program. Also, their versatility allows equipping sets of sensors suitable for observations both of winter or summering sea ice. In addition, the research team are able to use different operational bases for the airborne surveys to collect information from different regions of the Arctic Ocean and within the Canadian Archipelago. Another important role of the campaign series is that the team can link the aircraft observations to those from satellite to improve year-around observational capability of the Polar Regions. Here, the airborne measurements in summer, bridge the lack of satellite-based thickness observations during the melt phase of Arctic sea ice. Whenever possible, the aircraft observations will also be coordinated with international scientific groups and outreach activities to maximize the impact on research and public knowledge. The project will use a specially modified DC-3 research aircraft, owned by the Alfred Wegener Institute, fitted with scientific instruments that will be used to collect data. Airborne observations and data will be collected while based at five different locations across the Arctic. At each location, research flights will be conducted with a range of approximately 300km. The planned flight altitudes are between 60m and 600m, with low altitude flights only making up approximately 20 minutes of each flight. The core sensor set of the Ice Bird campaigns is a combination of an airborne electromagnetic sea-ice thickness sounder (EM-Bird) and an airborne laser scanner for the observations of sea ice surface properties. A snow radar for measuring snow depth on sea ice completes this setup in spring, while several RGB cameras, a hyperspectral camera as well as short- and long-wave radiation sensors are run additionally to study the temporal evolution and spatial variability of melt ponds on sea ice are used in summer. The location of the surveys are sea-ice covered regions near airports and bases in the high Arctic: During spring: 1. Longyearbyen, Spitsbergen, Norway; 2. Station Nord, Greenland, Denmark; 3. CFS Alert, Nunavut, Canada; 4. Weather Station Eureka, Nunavut, Canada; 5. Resolute Bay, Nunavut, Canada; 6. Inuvik, Northwest Territories, Canada; and, 7. Utqiagvik, Alaska, USA. During summer: 1. CFS Alert, Nunavut, Canada; 2. Station Nord, Greenland, Denmark. Calculation of carefully calibrated data and final processing of thickness measurements is scheduled in the month after the field campaigns. The processing of the raw data from the cameras and radiation sensors needs more time, about one year. Radiometric calibrations in optical laboratories after the campaign must be performed before final processing starts. Here it is important to correct very carefully for the aircraft movement (roll and pitch angles) and for the influence of the atmosphere (atmospheric correction). Sea ice change affects all who live in the north. Sea ice thinning and retreat are expected to continue as a result of climate change with a major uncertainty introduced by long-term natural climate variability. The aim of this project is to improve the understanding the processes contributing to variability to use these measurements to improve the regional and global climate models of the Arctic. Meetings are scheduled for the beginning of April with Aurora Research Institute and the Inuvik Hunters and Trappers Committee the first week of April. The results will be published in English in international peer-reviewed papers and communicated at international conferences. The research team also plan to conduct science communication via social media channels during and shortly after the field campaigns. In addition, the team want to strengthen the relationship to the local communities to inform about our research and to receive direct feedback from the people living in the areas we are interested in. First contacts to the Inuvik Hunters and Trappers Committee and Aurora Research Institute are made and will involve presentation and the request for advice of how to effectively reach out to communities. The fieldwork for this study will be conducted from April 10, 2019 to April 30, 2019.