Variability of surface energy fluxes over high latitude permafrost wetlands

Arctic ecosystems are undergoing a very rapid change due to the global warming and their response to climate change has important implications for the global energy budget. Therefore, it is crucial to understand how energy fluxes in the Arctic will respond to any changes in climate related parameters. However, attribution of these responses is challenging because measured fluxes are the sum of multiple processes that respond differently to environmental factors. Here, we present the potential of environmental response functions for quantitatively linking energy flux observations over high latitude permafrost wetlands to environmental drivers in the flux footprints. We used the research aircraft POLAR 5 equipped with a turbulence probe, fast temperature and humidity sensors to measure turbulent energy fluxes across the Alaskan North Slope with the aim to extrapolate the airborne eddy covariance flux measurements to the entire North Slope. After thorough data pre-processing, wavelet transform is used to improve spatial discretisation of flux observations and to quantify biophysically relevant land cover properties in the flux footprint. A boosted regression trees technique is then employed to extract and quantify the functional relationships between the energy fluxes and the environmental drivers. Finally, the resulting environmental response functions are used to extrapolate the sensible heat and water vapour exchange over spatio-temporally explicit grids of the Alaskan North Slope. The supplemented simulations from the Weather Research and Forecasting (WRF) model were used to explore the dynamics of the atmospheric boundary layer and to examine results of extrapolation