HR: 08:55h
AN: H31K-04 INVITED    [Abstracts]
TI: Advances in the Analytic Description of Canopy Radiation for Climate Models
AU: * Dickinson, R E
EM: robted@eas.gatech.edu
AF: Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332, United States
AB: Absorption of solar radiation drives canopy exchanges of energy, moisture, and carbon. Prior to FIFE Dickinson and Sellers advanced one dimensional analytic models for determining this absorption in the contexts of a climate model. Their models now form the basis for what is currently used in climate models. However, under many circumstances, the assumptions of such models about the geometry of canopies are too inaccurate for use without further improvement. They can be adequately constrained by remote sensing observations such as from MODIS to provide reasonable estimations of total absorbed solar energy. However, 3D geometric effects are important for determining the partitioning of this absorbed energy between different surfaces, e.g. canopy versus snow. More realistic 3D modeling of canopy radiation has advanced for remote sensing applications through use numerical models and lookup tables. Radiation measurements supporting such models have been made in multiple field programs. This talk will move from this historical perspective to a summary of what is now possible through use of analytic mathematics to characterize canopy radiation with 3D geometries. Such characterization provides several benefits: it is efficient enough to be useful for climate models and hence can evaluate the terrestrial radiative feedbacks of interest in that context; it describes the directionally of the outgoing radiation and so can be used in a climate model for assimilation of remote sensing information about the terrestrial system; its analytic structure provides insight into the underlying physics. It also is of relevance to determining of emissivity for vegetated surfaces in a climate model.
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0466 Modeling
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
SC: Hydrology [H]
MN: 2007 Fall Meeting