Evaluation of seasonal atmosphere–biosphere exchange estimations with TCCON measurements 1California Institute of Technology, Pasadena, CA, USA
17 May 2013
2Jet Propulsion Laboratory, Pasadena, CA, USA
3Institute of Environmental Physics, Bremen, Germany
Received: 30 Apr 2012 – Published in Atmos. Chem. Phys. Discuss.: 22 May 2012Abstract. We evaluate three estimates of the atmosphere-biosphere exchange against
total column CO2 observations from the Total Carbon Column Observing
Network (TCCON). Using the GEOS-Chem transport model, we produce forward
simulations of atmospheric CO2 concentrations for the 2006–2010 time
period using the Carnegie-Ames-Stanford Approach (CASA), the Simple Biosphere
(SiB) and the GBiome-BGC models. Large differences in the CO2
simulations result from the choice of the atmosphere-biosphere model. We
evaluate the seasonal cycle phase, amplitude and shape of the simulations.
The version of CASA currently used as the a priori model by the GEOS-Chem
carbon cycle community poorly represents the season cycle in total column
CO2. Consistent with earlier studies, enhancing the CO2 uptake in
the boreal forest and shifting the onset of the growing season earlier
significantly improve the simulated seasonal CO2 cycle using CASA
estimates. The SiB model gives a better representation of the seasonal cycle
dynamics. The difference in the seasonality of net ecosystem exchange (NEE)
between these models is not the absolute gross primary productivity (GPP),
but rather the differential phasing of ecosystem respiration (RE) with
respect to GPP between these models.
Revised: 20 Mar 2013 – Accepted: 08 Apr 2013 – Published: 17 May 2013
Citation: Messerschmidt, J., Parazoo, N., Wunch, D., Deutscher, N. M., Roehl, C., Warneke, T., and Wennberg, P. O.: Evaluation of seasonal atmosphere–biosphere exchange estimations with TCCON measurements, Atmos. Chem. Phys., 13, 5103-5115, doi:10.5194/acp-13-5103-2013, 2013.