GREENHOUSE GAS EMISSIONS FROM ARCTIC FRESHWATERS: APPROACHES FOR SCALING UP

Abstract:

Turbulence moderates emissions of greenhouse gases on a number of scales, and it, in turn, is moderated by processes which govern the stability of boundary layers. On the smallest scale, it mediates the fluxes of gases across the air-water interface; at intermediate scales, that is, the size of within lake eddies, it brings gases to the air-water interface; on a larger scale, eddies in the unstable atmospheric boundary layers transport gases away from water bodies and maintain concentration gradients and further, help sustain fluxes by inducing within lake turbulence. The winds and cooling which induce within-lake turbulence and over-lake boundary layers are moderated by weather patterns dependent on even larger scale physical processes. Using time series measurements of lake temperatures, surface meteorology, and profiles of temperature-gradient microstructure in Alaskan arctic lakes ranging from 0.1 to 150 ha in surface area, we quantify the dependency of turbulence in the water column and at the air-water interface on surface meteorology and lake size. We show the lake size dependent variability in the stability of atmospheric boundary layers. We illustrate the resulting lake-size and weather dependent variability in gas transfer coefficients and within lake mixing. Using cluster analysis, we identify dominant weather patterns in the Alaskan Arctic Region and link them to within lake mixing dynamics. We then illustrate the dependency of greenhouse gas emissions on variability in local weather, lake size, and weather patterns.