HR: 08:00h
AN: B21E-01 INVITED     [Abstracts]
TI: Regional-Scale Carbon Flux Estimates Over Complex Terrain and the Airborne Carbon in the Mountains Experiment
AU: * Stephens, B
EM: stephens@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: Aulenbach, S
EM: aulenbac@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: Campos, T
EM: campos@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: De Wekker, S
EM: stephan.dewekker@pnl.gov
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: Monson, R
EM: Russell.Monson@colorado.edu
AF: University of Colorado, EBIO Campus Box 334, Boulder, CO 80309-0334
AU: Ojima, D
EM: dennis@nrel.colostate.edu
AF: Colorado State University, NESB, B229, Fort Collins, CO 80523-1499
AU: Running, S
EM: swr@ntsg.umt.edu
AF: University of Montana, School of Forestry, Missoula, MT 59812
AU: Sacks, B
EM: sacks@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: Schimel, D
EM: schimel@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: Sun, J
EM: jsun@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80307-3000
AU: Lai, C
EM: lai@biology.utah.edu
AF: University of Utah, Department of Biology, 257S 1400E, Salt Lake City, UT 84112-0840
AB: Mountain forests represent a large portion of gross primary productivity within the United States and a significant potential net CO2 sink. Because of their importance to current and future national carbon budgets, the complexity of their controlling processes, and their sensitivity to land-use practices and climate change, NACP strategies must be devised to address how to distinguish and partition carbon fluxes in montane regions. We conducted the first Airborne Carbon in the Mountains Experiment (ACME I) in May and July of this year to explore methods for constraining regional-scale CO2 fluxes over complex terrain and to collect measurements useful for devising and testing strategies for long-term monitoring of these fluxes. We flew a total of 54 hours on the NCAR C-130 aircraft over large regions of the Colorado Rocky Mountains, making continuous measurements of CO2, CO, O3, and water vapor concentrations, and collecting discrete flask samples for 13C and 18O isotope ratios in CO2. In addition to these primary measurements, we also flew a scanning radiometer with thermal and vegetation channels, collected flask samples for radiocarbon measurements and for verification of our in situ CO2 and CO measurements, and collected high rate CO2, CO, O3, and water vapor data for direct eddy-correlation flux estimates. Our airborne measurements will be compared to and integrated with the extensive ongoing carbon and ecosystem measurements at Niwot Ridge and an enhanced network of ground-based measurements deployed as part of the broader Carbon in the Mountains Experiment. The flights were conducted according to a combination of experimental designs, including morning to afternoon Lagrangian flux measurements, regional survey measurements for assimilation into a high-resolution ecosystem-atmosphere model, morning sampling of nocturnally respired CO2 and its concentration by topography and dispersion by turbulence, flask sampling to resolve elevation gradients in isotope signatures, and direct flux measurements. During the Lagrangian experiments and regional surveys, we observed CO2 drawdowns of several ppm in boundary-layer CO2, representing significant CO2 uptake by the forests and strong signals for use in our analyses. Also, in large mountain valleys we observed on the order of 30 ppm of respired CO2 pooling as deep as 1000 ft. and persisting until 10 AM, which may suggest techniques for making respiration estimates on relatively large scales. We will present results of our preliminary analyses and discuss strategies the NACP should consider to improve constraints on mountain carbon fluxes.
DE: 9350 North America
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting