HR: 0800h
AN: B41G-0391 Poster
TI: Monthly Anthropogenic CO2 fluxes: Impacts on the atmospheric CO2 seasonal cycle and implications for models of the terrestrial biosphere
AU: *Allen, M R
EM: mallentn@earthlink.net
AF: Oak Ridge National Laboratory, Knoxville, TN, USA
AU: Erickson, D J
EM: ericksondj@ornl.gov
AF: Oak Ridge National Laboratory, Knoxville, TN, USA
AU: Andres, R J
EM: andresrj@ornl.gov
AF: Oak Ridge National Laboratory, Knoxville, TN, USA
AU: Hoffman, F M
EM: forrest@climatemodeling.org
AF: Oak Ridge National Laboratory, Knoxville, TN, USA
AU: Branstetter, M L
EM: branstetterm@ornl.gov
AF: Oak Ridge National Laboratory, Knoxville, TN, USA
AB: We describe a simulation of atmospheric carbon dioxide (CO2) in the Community Atmosphere Model Version 4.1 (CAM4.1) from 1850-2010 specifically focused on a unique fossil fuel surface source with monthly seasonality. The amplitude of atmospheric CO2, driven with the monthly anthropogenic CO2 source only, is distinctly different in the mid-1800’s and exhibits increasing trends as the simulation evolves to the present day. We find that for the 1960’s -1980’s the amplitude of atmospheric CO2 at stations such as the Azores is 0.4-0.8 ppm, Mauna Loa is 0.2-0.4 ppm and at the South Pole is 0.1-0.2 ppm. This is comparable to the impact of implementing the range of plausible variables that contribute to the calculation of NPP in models of the terrestrial biosphere. The fossil fuel induced CO2 amplitudes rise to 2-4 ppm over select continental regions, resulting in significant implications for inverse modeling interpretations. An additional point is that the amplitude of the seasonal cycle increases over time at both remote (i.e. island) and continental stations from 1940-2000. The common practice of tuning terrestrial biosphere parameters to achieve agreement with the observed amplitude of atmospheric CO2 will need to be reevaluated once the impact of temporally varying anthropogenic emissions of CO2 are taken into account in global climate model based simulations of the carbon cycle. There is also an indication that, in addition to the temporal trends (i.e. decadal) in the amplitude of the seasonal cycle, there is a steady changing in the phasing of the amplitude of CO2. The atmospheric dynamics of the seasonal cycle of atmospheric CO2 has been changing in amplitude and phasing due directly to trends in anthropogenic CO2 emissions. This has significant implications for inverse studies seeking the surface source/sink regions for atmospheric CO2 since these patterns in atmospheric CO2 distributions have changed non-linearly over the last 10-100 years.
DE: [0428] BIOGEOSCIENCES / Carbon cycling
DE: [0466] BIOGEOSCIENCES / Modeling
DE: [1615] GLOBAL CHANGE / Biogeochemical cycles, processes, and modeling
DE: [1626] GLOBAL CHANGE / Global climate models
SC: Biogeosciences (B)
MN: 2010 Fall Meeting