HR: 13:55h
AN: H43H-02    [Abstracts]
TI: Topographic variability and the disbalance between water vapor turbulent fluxes and evapotranspiration
AU: * Katul, G
EM: gaby@duke.edu
AF: Duke University, Nicholas School of the Environmenta and Earth Sciences, Box 90328, Durham, NC 27708-0328 United States
AU: Poggi, D
EM: davide.poggi@polito.it
AF: Politecnico di Torino, Dipartimento di Idraulica, Trasporti e Infrastrutture Civili, Torino, 10137 Italy
AB: Virtually all recent reviews concerning surface-atmosphere water vapor and momentum exchange have expressed the need to confront the problem of turbulent flows within plant canopies on non-flat terrain. In particular, the presence of topographic variability induces advective fluxes that disbalance the one-to-one relationship between plant evapotranspiration (ET) and the turbulent water vapor flux above the canopy. With the advancements in canopy LIDARS, information about topographic variability, canopy height, and leaf area density are becoming available at unprecedented spatial resolution. What is clearly missing is a simplified framework to link velocity perturbations within and above the canopy to topographic variations using such remote sensing products so that the disbalance between the desired ET and the turbulent water vapor flux can be established. In this study, we report on both flume experiments and model calculations that explore the connections between topographic variability, the onset of mean advective fluxes, and the disbalance between ET and turbulent water vapor fluxes on gentle ridges whose height is comparable to the canopy height. Model calculations suggest that the variations in advection and turbulent eddy flux across the hill are relatively independent of the source-sink distribution of water vapor in the canopy. The implications of this finding is that it is possible to correct systematically for advection using standard techniques of data assimilation and inverse modeling.
UR: http://www.nicholas.duke.edu/people/faculty/katul/homepage.html
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1813 Eco-hydrology
DE: 1818 Evapotranspiration
SC: Hydrology [H]
MN: Fall Meeting 2005