HR: 1340h
AN: B33B-1036 [Abstracts]
TI: Role of Atmospheric Scattering on Canopy Light Penetration and Net Ecosystem Exchange of CO2 in a
Mid-Western Mixed Deciduous Forest
AU: Oliphant, A J
EM: andrewo@sfsu.edu
AF: San Francisco State University, Department of Geography, 1600 Holloway Avenue, San Francisco, CA 94132
United States
AU: * Rose, J
B33B-1036
AF: San Francisco State University, Department of Geography, 1600 Holloway Avenue, San Francisco, CA 94132
United States
AU: Grimmond, C B
B33B-1036
AF: Indiana University, Department of Geography, 701 E. Kirkwood Avenue, Bloomington, IN 47405-7100
United States
AU: Schmid, H
B33B-1036
AF: Indiana University, Department of Geography, 701 E. Kirkwood Avenue, Bloomington, IN 47405-7100
United States
AB:
Understanding long-term change in terrestrial carbon sequestration dynamics is an important goal for modeling future change
for Earth's climate. This paper presents evidence for consistently enhanced ecosystem productivity of over 20% under
cloudy conditions for a mid-western deciduous forest, despite reduction in total solar radiation of up to 50%. This result
is based on analyses of the relationship between atmospheric scattering, light penetration within the canopy and net
ecosystem exchange of CO2 for the Morgan-Monroe State Forest AmeriFlux flux tower site in south-central Indiana. Data
presented include observations and modeling of diffuse and direct components of photosynthetically active radiation (PAR),
eddy covariance measurements of CO2 fluxes and a canopy tower instrumented with nine levels of quantum sensors within
the canopy. The role of atmospheric scattering on NEE is considered in the context of climatological and hydrological
background controls and phenological development from a seven-year dataset. The mechanism of enhanced canopy light use
efficiency is investigated through analysis of the vertical profile of canopy PAR with respect to the vertical distribution
of LAI under varying sky conditions. New parametric equations for light use efficiency of the forest dependent on atmospheric
scattering are presented.
DE: 0360 Radiation: transmission and scattering
DE: 0426 Biosphere/atmosphere interactions (0315)
SC: Biogeosciences [B]
MN: Fall Meeting 2005