Carbon Dioxide Measurements in the Nocturnal Boundary Layer over Amazonian Tropical Forest

This chapter presents some of Carbon dioxide (CO₂) profile data obtained during Manaus Atmospheric CO₂ Experiment (MACOE) and examines the carbon budget from a mass balance inside the Nocturnal Boundary Layer between the derived profile and from turbulent fluxes. The data set from MACOE and from Grace et al. point out an increase of CO₂ flux and concentration just after sunrise, due to the breakdown of the thermal stability at canopy level and onset of the turbulence. The MACOE experiment was conducted in order to make regional CO₂ budgets over tropical forest in central Amazonia. Tropical forest represents significant sources/sinks for trace gases, and the exchange of CO₂ between forest and the atmosphere is an important component of the global carbon cycle because of its greenhouse effect. Direct measurements of CO₂ exchange between vegetation and the atmosphere are becoming more common, although little data have been collected over tropical forest and for only limited periods.