HR: 16:15h
AN: B52E-02    [PDF]
TI: Assimilation of Remotely Sensed Data into the Biome-BGC Ecosystem Model to Improve the Prediction of Energy and Carbon Exchange in Southwestern Mountain Island Forests
AU: * Brown-Mitic, C M
EM: connie@hwr.arizona.edu
AF: SAHRA, University of Arizona, Dept. of Hydrology and Water Resources, Tucson, AZ 85721-0011 United States
AU: Burke, E J
EM: eleanor@hwr.arizona.edu
AF: SAHRA, University of Arizona, Dept. of Hydrology and Water Resources, Tucson, AZ 85721-0011 United States
AU: Shuttleworth, W J
EM: shuttle@hwr.arizona.edu
AF: SAHRA, University of Arizona, Dept. of Hydrology and Water Resources, Tucson, AZ 85721-0011 United States
AU: Petti, J R
EM: jrp@hwr.arizona.edu
AF: SAHRA, University of Arizona, Dept. of Hydrology and Water Resources, Tucson, AZ 85721-0011 United States
AU: Harlow, R C
EM: chawn@hwr.arizona.edu
AF: SAHRA, University of Arizona, Dept. of Hydrology and Water Resources, Tucson, AZ 85721-0011 United States
AU: Brooks, P D
EM: brooks@hwr.arizona.edu
AF: SAHRA, University of Arizona, Dept. of Hydrology and Water Resources, Tucson, AZ 85721-0011 United States
AB: Mountain island forest ecosystems populate high-altitude areas in the semi-arid southwestern U.S. and northwestern Mexico. In these regions, on average, the precipitation input exceeds the evapotranspiration loss. Therefore, they represent the primary source area for sustainable water resources, as well as making a major contribution to the regional carbon balance. During 2002 a 30-m tall micrometeorological tower was installed at a sky island forest site in the Santa Catalina Mountains, near Tucson AZ in order to characterize the surface exchanges of water, energy, and carbon. Measurements to date indicate that the surface fluxes are very sensitive to water status, for example, stomatal functioning totally closed down during the pre-monsoon period in 2002. Initial studies with the Biome Biogeochemical model (Biome-BGC) using driving data measured in the Santa Catalina Mountains provide reasonable simulations of the behavior of the mountain island forest. In order to obtain a regional estimate of the carbon exchange using a model such as Biome-BGC accurate estimates of the distributed forcing data particularly the precipitation are required. Alternatively, an estimate of the soil water status and the leaf area index can be used to improve model predictions. TERRA-MODIS leaf area index and fraction of photosynthetically active radiation (FPAR) are both sensitive to drought stress. Time periods during which there is a marked and sustained decrease in FPAR are shown to be symptomatic of a sustained period of low soil moisture that started 10-20 days earlier. Under these conditions the soil moisture status in Biome-BGC can be set to an arbitrary low value. Initial modeling studies demonstrate significant improvement in the prediction of surface exchange when using FPAR to diagnose periods of water stress.
DE: 1878 Water/energy interactions
DE: 3322 Land/atmosphere interactions
SC: Biogeosciences [B]
MN: 2003 Fall Meeting