CONTROL ID: 1488306

TITLE: Spatiotemporal pattern of CLM4 simulated evapotranspiration in response to multifactor environmental changes

AUTHORS (FIRST NAME, LAST NAME): Xiaoying Shi1, Jiafu Mao1, Peter E Thornton1, Forrest M Hoffman2

INSTITUTIONS (ALL): 1. Environmental Science Division, Oak Ridge National Lab, Oak Ridge, TN, United States.
2. Computer Science and Mathematics Division, Oak Ridge National Lab, Oak Ridge, TN, United States.

ABSTRACT BODY: Spatial and temporal patters of evapotranspiration (ET) are investigated and attributed to multifactor environmental changes using Community Land Model version 4 (CLM4) over the time period 1982 to 2008. The CLM4 captures well the spatial distribution and interannual variability compared to observation-based data using model tree ensembles (MTE) approach. However, the climate trends and variability alone, are not sufficient to account for the total changing rates of ET. On the basis of the model results, we find that climate does dominate to ET change, and the elevated atmospheric CO2 concentration also plays an important role in controlling the trend of ET (considering both the CO2-physiological and CO2-sturctural forcing) over most parts of global land surface. While, CO2 takes place the climate to be the primary driving factor over North America, South America and Asia. The roles of other non-climate factors such as nitrogen deposition, land use change and aerosol deposition are region dependent. For example, the aerosol deposition contribution is the third important for the trends of ET over Europe, while it has the smallest impact on the ET trend over the other regions. Process-based CLM4 reveals that the non-climate environmental factor may affect the projections of water resources and climate.

KEYWORDS: [0414] BIOGEOSCIENCES / Biogeochemical cycles, processes, and modeling.
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CONTACT (E-MAIL ONLY): shix at ornl dot gov