期刊
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
卷 119, 期 10, 页码 1947-1969出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2014JG002717
关键词
Alaska; energy fluxes; upscaling; snow albedo; forest fire; eddy covariance
资金
- Environment Research and Technology Development Fund of the Ministry of the Environment, Japan [RFa-1201]
- National Science Foundation
- National Science Foundation Division of Polar Programs
- Next-Generation Ecosystem Experiments (NGEE Arctic) project - Office of Biological and Environmental Research in the DOE Office of Science
- Grants-in-Aid for Scientific Research [26550100, 26281012] Funding Source: KAKEN
Warming in northern high latitudes has changed the energy balance between terrestrial ecosystems and the atmosphere. This study evaluated changes in regional surface energy exchange in Alaska from 2000 to 2011 when substantial declines in spring snow cover due to spring warming and large-scale fire events were observed. Energy fluxes from a network of 20 eddy covariance sites were upscaled using a support vector regression (SVR) model, by combining satellite remote sensing data and global climate data. Based on site-scale analysis, SVR reproduced observed net radiation, sensible heat flux, latent heat flux, and ground heat flux; 8 day root-mean-square errors for these variables were 15, 10, 9, and 3Wm(-2), respectively. Based on upscaled fluxes, decreases in spring snow cover induced an increase in surface net radiation, a net heating effect, of 0.56Wm(-2) decade(-1). This heating effect was comparable to the net cooling effect due to increased fire extent during the study period (up to 0.59Wm(-2) decade(-1)). These land cover effects were larger than the change in the energy forcing associated with CO2 balance for the Alaska region. Spring warming and postfire land cover change increased the regional latent heat flux. The regional sensible heat flux decreased with the postfire land cover change. Our results highlight the importance of positive spring snow albedo feedback to climate and a postfire negative feedback under the expected warming climate in the Arctic.
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