| Anthropogenic activities have significantly changed the atmospheric greenhouse gases composition. Specifically the CO2 concentration has risen steadily since the mid-18th century, the current
rate of growth is about 1.4 ppmv/year globally averaged. This partially accounts for the anthropogenic emission of CO2. There is great scientific interest in determining where the reminder of the anthropogenic CO2 is going and
the processes involved, as understanding these processes may lead to useful predictions of future greenhouse gases concentrations in the atmosphere. The main reservoirs of CO2 on a daily to decadal time scales are the atmosphere,
biosphere and ocean. Where the anthropogenic CO2 goes is determined by the exchange processes between the major reservoirs. To study the exchange processes and their governing factors between the biosphere and the atmosphere on a daily to
annual time scale and on the mesoscale space scale, we are coupling a mesoscale atmospheric model to a mesoscale (landscape scale) biospheric CO2 flux model. The atmospheric model is the Mesoscale Compressible Community (MC2) model
(Benoit et al., 1997). The MC2 model is a full-elastic non-hydrostatic model, it solves a full set of Euler equations on a limited area domain with time-dependent nesting of the lateral boundary conditions supplied by a large-scale model. The nesting
capability of MC2 allows the study of processes over a wide spectrum of scales. The biospheric CO2 flux model is the Boreal Ecosystem Productivity Simulator (BEPS) (Liu et al., 1997). BEPS is a process model using the principles of
FOREST biogeochemical cycles (FOREST-BGC) (Running and Couglan, 1988) for quantifying the biophysical processes governing ecosystems productivity, but with modifications to better represent canopy radiation processes. The processed remote sensing
data required by the model are the leaf area index (LAI) and land cover type. The meteological data include air temperature, incoming shortwave radiation, precipitation and humidity. The soil-data input is the available water-holding capacity.
This study will discuss the modifications to these models and compare the results of these models to the observational measurements obtained at a boreal forest CO2 monitoring site (Fraserdale). |