HR: 0800h
AN: H51D-01    [Abstracts]
TI: Foliage Temperature Profile Modeling: The Role of Canopy Density and Stomatal Resistance Profiles
AU: * Crago, R D
EM: rcrago@bucknell.edu
AF: Bucknell University, Department of Civil and Environmental Engineering, Lewisburg, PA 17837, United States
AU: Qualls, R
EM: rqualls@uidaho.edu
AF: University of Idaho, Department of Agricultural and Biological Engineering P.O. Box 440904, Moscow, ID 83844, United States
AU: Zhao, W
EM: wzhao@uidaho.edu
AF: University of Idaho, Department of Agricultural and Biological Engineering P.O. Box 440904, Moscow, ID 83844, United States
AB: Land surface energy fluxes play a key role in the hydrology, weather and climate of a region, and the land surface temperature (Ts) is a key variable in most land surface models (LSMs) used to calculate them. Many LSMs make use of remotely sensed (radiometric) Ts. Most of them use either a single lumped Ts value or distinguish between the soil surface temperature and the lumped foliage temperature. However, even within the foliage itself, recent measurements by two of the present investigators have shown well-defined vertical leaf temperature (Tf) profiles. Such profiles are handled explicitly in very few LSMs. To address this problem, a Localized Near Field (LNF) Lagrangian transport canopy model has been developed. This model combines the LNF theory proposed by M. Raupach with the combination equation applied to thin horizontal layers of the canopy to determine the energy budget for each layer. Required input data are net radiation, canopy density distribution, stomatal resistance distribution, and wind speed, air temperature, and humidity above the canopy. The model calculates momentum flux, H, and LE, as well as vertical distributions of heat and vapor source strengths, air temperature, humidity, and foliage temperature. The model is applied to data from the Southern Great Plains (SGP-97) experiment from a dense (LAI-4.0, canopy height 0.6 m) grassy site. The model was run with three different assumed foliage density distributions, all of which had a total LAI of 4.0, and two different stomatal resistance profile shapes. A key finding of this study is that the shape of the modeled Tf profiles can vary considerably depending on the assumed foliage density and stomatal resistance profiles. For example, during the middle of the day, foliage density profiles that have maximum density near the middle of the canopy also developed Tf maxima near the middle of the canopy, but uniform foliage density profiles developed Tf maxima at the top of the canopy. A better understanding of these interactions is essential for proper interpretation of remotely sensed values of Ts.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1855 Remote sensing (1640)
DE: 3307 Boundary layer processes
SC: Hydrology [H]
MN: 2007 Joint Assembly