The exchange of energy, momentum, water vapor and trace gases and particles between the earth's surface and the atmosphere have significant impacts on the dynamics and composition of the atmosphere. Terrestrial ecosystems, and forests in particular, play a critical role in these surface-atmosphere exchange processes and thereby greatly influence weather, climate and air quality. An AmeriFlux site in the southern Appalachians has obtained nearly three decades of forest micrometeorological and carbon flux observations and is undergoing a major upgrade to enhance its ability to characterize the carbon budget and increase scientific understanding of surface-atmosphere exchange processes.  Research topics for this project could include: (1) analysis of historical data from the site focused on trends in net ecosystem exchange (NEE) and evapotranspiration (ET), and the impact of climate change on those trends; (2) evaluation of the representativeness of the site's measurements at the landscape scale; (3) implementation, quality control and analyses of enhanced multi-layer forest micrometeorological and CO2/CH4 flux measurements; or (4) modeling to account for complex terrain effects in land-atmosphere interactions and landscape-scale fluxes.