The exchange of momentum, energy, moisture, trace gases and aerosols play a critical role in weather, climate and air quality. These complex processes involve ambient concentrations of the species of interest, biochemical conditions of the exchange surface, biological processes of the underlying ecosystem, boundary-layer physics and micro-meteorology, and fast chemical reactions that create discrepancies between leaf- and canopy-scale fluxes. While accurate representations of these processes are critical for atmospheric composition models, wide knowledge gaps persist, particularly as the resolved length scales of the models continues to shrink and as the climate continues to warm. In this session, measurement scientists and modelers will come together to discuss recent studies that further our understanding of the physical, chemical and biological processes that control exchanges, interactions and feedbacks between the Earth’s surface and the atmosphere. Presentations are encouraged on new measurements or measurement methods, new modeling approaches, inter-comparison of different models or different measurement methods, long-term studies or intensive measurement campaigns, and over a variety of land surface types, including temperate, tropical or boreal forests, coastal or ocean surfaces, desert, tundra or snow-covered or icy surfaces. Studies on quantifying emissions and atmospheric deposition of various chemical pollutants from local to regional scales are also welcome.