Surface-atmosphere Interactions in Canada’s Low Arctic

Elyn Humphreys, Carleton University, elyn_humphreys@carleton.ca (Presenter)
Peter Lafleur, Trent University, plafleur@trentu.ca

The low Arctic tundra in the eastern portion of the ABoVE study domain includes many surface types including lakes, ponds, wetlands, and tundra with varying soil depth and shrub cover. Observations of ecosystem-scale and plot-scale carbon dioxide, methane, energy and water exchanges have been ongoing since 2004 at the Daring Lake Tundra Ecosystem Research Station to characterize the spatial and temporal variability in surface-atmosphere interactions in this landscape. In 2017, we observed large seasonal variations in methane fluxes at a sedge fen and in net ecosystem exchange of CO2 and evapotranspiration at three tundra sites with varying shrub cover. In past growing seasons we found greater net uptake of CO2 with greater shrub cover but no concurrent increase in evapotranspiration. Snow depth increases with greater and taller shrub cover and along with moss cover, influences winter soil temperatures and active layer development. Greater shrub cover does not reduce late-winter albedo at our sites but does increase summer albedo and sensible heating of the atmosphere. Thus, our research reinforces existing knowledge of certain shrub tundra climate feedbacks and refutes others. Recent shoulder and winter season measurements of CO2 fluxes are being analyzed to help assess the annual carbon sink or source strength of these ecosystems.

Poster Location ID: 34

Session Assigned: Carbon Dynamics