HR: 0800h
AN: C21C-1112    [Abstracts]
TI: Parameter Sensitivity of the Arctic BIOME BGC model for Estimating Evapotranspiration
AU: * Engstrom, R N
EM: rengstro@gwu.edu
AF: Department of Geography George Washington University, 1957 E. St., NW, Suite 512, Washington, DC 20052 United States
AU: Hope, A
EM: hope1@mail.sdsu.edu
AF: Department of Geography San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-4493 United States
AB: Modeling evapotranspiration (ET) in Arctic coastal plain ecosystems is challenging due to the unique environmental conditions, including non-vascular vegetation, permafrost, and a large standing dead vegetation component. In a previous study, the commonly used ecosystem process model, BIOME BGC, was modified to include representations of these unique Arctic conditions. The modifications resulted in a new model, Arctic BIOME BGC that significantly reduced the random and systematic errors when compared to eddy flux tower measurements. However, the modifications made in Arctic BIOME BGC added complexity and a number of new parameters. In this study the generalized sensitivity analysis methodology was used to examine the Arctic BIOME BGC model sensitivity to the thirteen parameters in the application of estimating daily ET over a four year time period in the Arctic coastal plain. The thirteen parameters investigated represented those which most directly impact model ET estimates and include all of the new ones added in the development of Arctic BIOME BGC. Results indicate that the model was highly sensitive to eight of the thirteen parameters. This suggests that the new process representations added in Arctic BIOME BGC were important for modeling ET in these ecosystems. Two parameters, standing dead leaf area index and snow absorptivity, had unique, identifiable values that corresponded well to observed data. Overall, there were many physically realistic parameter sets that were able to produce acceptable model predictions indicating that parameter equifinality is present within the model.
DE: 0718 Tundra (9315)
DE: 0764 Energy balance
DE: 0798 Modeling
SC: Cryosphere [C]
MN: Fall Meeting 2005