Modeling of CO2 fluxes between atmosphere and boreal forest

Abstract

Difficulties in estimating terrestrial ecosystem CO2 fluxes on regional scales have significantly limited our understanding of the global carbon cycle. We present a method of using tall-tower-based CO2 concentrations for estimating CO2 fluxes over a forested region. With long-term measurements of the CO2 mixing ratio at a 300-m-tall tower, regional CO2 fluxes were estimated for several months, from the first obtained data. Estimates of a monthly-integrated surface CO2 flux over the region were obtained by the analysis of average gradients and estimates of the rate of vertical mixing between the atmospheric boundary layer (ABL) and the free troposphere. For the comparison of the ABL budget method and field measurements a zero-dimensional mathematical model of the ecosystem of Siberian boreal forests was used. The model is a system of ordinary differential equations with additional conditions superimposed on the parameters. The main occurring processes are described – photosynthesis, respiration, seasonal changes of active phytomass, water balance of trees, the influence of light, humidity, and temperature on photosynthesis and respiration.