9629497 Lee Sequestering of atmospheric CO2 by forest vegetation is a process that is important to the biogeochemical carbon cycle. This exchange process is not well understood in a quantitative sense, particularly for nocturnal conditions occurring within the planetary boundary layer. The research focuses on the factors that control nocturnal fluxes of CO2 and other scalars between the biosphere and atmosphere. The project will examine atmospheric exchange at a process-level by using micrometeorological methods and it is intended to advance current techniques that quantify carbon exchange over vegetation canopies. This effort is a modeling study that will analyze currently available micrometeorological, boundary layer data for two sites located within a boreal forest ecosystem of Ontario, Canada (i.e., BOREAS experiment, summer 1993). The PI will also analyze micrometeorological data sets that will be obtained from two planned ecosystem boundary layer experiments: the Great Mountain Forest (GMF), Connecticut (site operational April 1996), and the Farm River Salt Marsh, New Haven, Connecticut (project planned 1998, funded by the Connecticut Sea Grant Program). The four experimental sites are selected on the basis of canopy profile (e.g., height, morphology, vegetation composition). Analyses of the micrometeorological data from these sites are intended to improve the present understanding of the dynamic coupling between vegetation and atmospheric flow and how this coupling affects larger scale forest-atmosphere interactions and boundary-layer turbulence. *** ATM-9629497