HR: 11:35h
AN: H11H-06    [PDF]
TI: Preferential States in Continental Soil Moisture and Climate Dynamics
AU: D'Odorico, P
EM: paolo@virginia.edu
AF: University of Virginia, Department of Environmental Sciences Box 400123, 291 McCormick Rd., Charlottesville, VA 22904-4123 United States
AU: * Pipino, N
EM: n_pip@libero.it
AF: Politecnico di Torino, Dipartimento di Idraulica e Trasporti, Corso Duca degli Abruzzi, 24, Torino, 10129 Italy
AU: Porporato, A
EM: porporato@polito.it
AF: Duke University, Department of Civil and Environmental Engineering, Box 90287; Hudson Hall, Durham, NC 27708-0287 United States
AB: Summer precipitation in continental midlatitude regions is significantly contributed by local recycling, i.e. by moisture returning to the atmosphere as water vapor through evapotranspiration from the same region. In the summer months, soil moisture availability may limit water vapor fluxes from the soil surface to the planetary boundary layer, with important effects on the regional climate. It has been argued that important dynamics arise from such land-atmosphere interactions, including drought occurrence sustained by positive feedbacks in response to initial (spring/beginning of summer) surface moisture anomalies. However, no conclusive evidences have been provided in support of the existence of such feedbacks. We provide further experimental evidences in support of the hypothesis that, in continental regions, summertime soil moisture anomalies affect subsequent precipitation. We also test the hypothesis that, due to soil moisture-precipitation feedbacks, summertime soil moisture dynamics have two preferential states evidenced by the existence of a double mode in the probability distribution of soil moisture, while intermediate conditions have low probability of occurrence. In support of these central goals we analyze existing soil moisture records from Illinois and develop simple stochastic water balance models to study the effect of precipitation recycling on summer soil moisture dynamics.
DE: 1866 Soil moisture
DE: 1869 Stochastic processes
DE: 3322 Land/atmosphere interactions
DE: 3354 Precipitation (1854)
SC: Hydrology [H]
MN: 2003 Fall Meeting