Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/gmd-2017-169
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Development and technical paper
11 Sep 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Geoscientific Model Development (GMD).
Coupling the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0) to Environment and Climate Change Canada's greenhouse gas forecast model
Bakr Badawy1,a, Saroja Polavarapu1, Dylan B. A. Jones2, Feng Deng2, Michael Neish1, Joe R. Melton3, Ray Nassar1, and Vivek K. Arora3 1Climate Research Division, Environment and Climate Change Canada, Toronto, Canada
2Department of Physics, University of Toronto, Toronto, Canada
3Climate Research Division, Environment and Climate Change Canada, Victoria, Canada
anow at: Faculty of Environment, University of Waterloo, Canada
Abstract. The Canadian Land Surface Scheme and the Canadian Terrestrial Ecosystem Model (CLASS-CTEM) together form the land surface component in the family of Canadian Earth System Models (CanESM). Here, CLASS-CTEM is coupled to Environment and Climate Change Canada (ECCC)'s weather and greenhouse gas forecast model (GEM-MACH-GHG) to consistently model atmosphere-land exchange of CO2. The coupling between the land and the atmospheric transport model ensures consistency between meteorological forcing of CO2 fluxes and CO2 transport. The procedure used to spin up carbon pools for CLASS-CTEM for multi-decadal simulations needed to be significantly altered to deal with the limited availability of consistent meteorological information from a constantly changing operational environment in the GEM-MACH-GHG model. Despite the limitations in the spin up procedure, the simulated fluxes obtained by driving the CLASS-CTEM model with meteorological forcing from GEM-MACH-GHG were comparable to those obtained from CLASS-CTEM when it is driven with standard meteorological forcing (CRU-NCEP). This is due to the similarity of the two meteorological datasets in terms of temperature and radiation. However notable discrepancies in the seasonal variation and spatial patterns of precipitation estimates, especially in the tropics, were reflected in the estimated carbon fluxes, as they significantly affected the magnitude of the vegetation productivity and, to a lesser extent, the seasonal variations in carbon fluxes. Nevertheless, the simulated fluxes based on the meteorological forcing from the GEM-MACH-GHG model are within the range of other estimates from bottom-up or top-down approaches. Indeed, when simulated fluxes obtained by driving the CLASS-CTEM model with meteorological data from the GEM-MACH-GHG model are used as prior estimates for an atmospheric CO2 inversion analysis using the adjoint of the GEOS-Chem model, the retrieved CO2 flux estimates are comparable to those obtained from other systems in terms of the global budget and the total flux estimates for the northern extratropical regions, which have good observational coverage. In data poor regions, as expected, differences in the retrieved fluxes due to the prior fluxes become apparent, but fall within the uncertainty bounds based on multi-inversion analyses. The coupling of CLASS-CTEM to an atmospheric transport model with carbon assimilation capabilities also provides insights into the limitations of CLASS-CTEM simulated CO2 fluxes through comparisons of simulated atmospheric CO2 with observations at selected flask stations. This capability can be used to continually assess and improve the terrestrial ecosystem modules of the CLASS-CTEM model.

Citation: Badawy, B., Polavarapu, S., Jones, D. B. A., Deng, F., Neish, M., Melton, J. R., Nassar, R., and Arora, V. K.: Coupling the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0) to Environment and Climate Change Canada's greenhouse gas forecast model, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2017-169, in review, 2017.
Bakr Badawy et al.
Bakr Badawy et al.
Bakr Badawy et al.

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Short summary
We assess the impact of using the meteorological fields from GEM-MACH-GHG to drive CLASS-CTEM. This coupling allows consistent meteorology between the ecosystem and transport models. the study provided insights into the deficiencies in the model, and data constraints. The results will be used to continually assess and improve the CLASS-CTEM model, and thus improve the Canadian Earth System Model which is used to address the question of the feedback between climate change and the carbon cycle.
We assess the impact of using the meteorological fields from GEM-MACH-GHG to drive CLASS-CTEM....
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