HR: 1340h
AN: B33D-1058    [Abstracts]
TI: Interactions Between Vegetation and Summertime Climate Variability Over North America Grasslands: A Coupled Stochastic Model
AU: * Wang, W
EM: wlwang@bu.edu
AF: Boston University, Dept. of Geography, 675 Commonwealth Ave., Boston, MA 02215
AU: Anderson, B T
EM: brucea@bu.edu
AF: Boston University, Dept. of Geography, 675 Commonwealth Ave., Boston, MA 02215
AU: Phillips, N
EM: nathan@bu.edu
AF: Boston University, Dept. of Geography, 675 Commonwealth Ave., Boston, MA 02215
AU: Kaufmann, R K
EM: kaufmann@bu.edu
AF: Boston University, Dept. of Geography, 675 Commonwealth Ave., Boston, MA 02215
AU: Huang, D
EM: dh@bu.edu
AF: Boston University, Dept. of Geography, 675 Commonwealth Ave., Boston, MA 02215
AU: Myneni, R B
EM: rmyneni@bu.edu
AF: Boston University, Dept. of Geography, 675 Commonwealth Ave., Boston, MA 02215
AB: A coupled linear model is derived in this paper to describe interactions between anomalous precipitation and vegetation over the North America Grasslands. The model is based on bio-hydrological characteristics in the semiarid environment, and has components to describe the water-related vegetation variability, the long-term balance of soil moisture, and the local recycling of precipitation. Analyses show that the model captures the observed vegetation dynamics and characteristics of summertime precipitation variability over the studied region. It demonstrates that vegetation has "red" frequency responses to the precipitation forcing and has intrinsic oscillatory variability at timescales of about 8 months. When coupled to the atmospheric fields, such vegetation signals tend to enhance the magnitudes of precipitation at interannual or longer timescales, but damp them at timescales shorter than 4 months; the oscillatory variability of precipitation at the growing season timescales (i.e., the 8-month period) is also enhanced. Similar "red" shifts are identified in power spectra of observed precipitation datasets. Characteristics of oscillation are also suggested by the autocorrelation structure of observed summertime precipitation and lagged correlations between it and vegetation from the preceding months. These results are further verified by Monte-Carlo experiments.
DE: 1655 Water cycles (1836)
DE: 1818 Evapotranspiration
DE: 1851 Plant ecology (0476)
DE: 1866 Soil moisture
SC: Biogeosciences [B]
MN: Fall Meeting 2005