Atmosphere-biosphere interactions and feedbacks in the Alaskan Arctic

The Arctic climate is changing faster than anywhere else on the planet, and these climatic changes impact on ecological communities, particularly in Alaska, where animal and human populations are forced to adapt to the changing conditions. Interactions and feedbacks between the atmosphere and the land surface and its vegetation in the Arctic play an important role in local and regional climate. Yet our understanding of these interactions is hampered by the major limitations of current feedback analysis methodologies. The overall aim of this study was to characterise the interactions and feedbacks between cloud cover and a range of important surface variables. First, the performance of a land surface model was improved by including site-specific observational data. Various methodologies compared model output with observed data to test the hypothesis that site-specific parameter values improve the simulation of vegetation in the land surface model used. Overall, these tests indicated that there was a modest advantage in using site-specific parameter values, and the results were applied in a regional climate model to more accurately represent interactions and feedbacks between the atmosphere and the main Alaskan Arctic vegetation types -tussock tundra, tall shrub and evergreen (spruce) forest.