Our interests include interactions between vegetation and atmospheric chemistry, climate, and air pollution.
Impacts of dry deposition on atmospheric composition
We are investigating the role of dry deposition, an often overlooked yet important loss pathway for numerous trace species, and its variations with meteorology and land use, in shaping observed distributions of ozone and aerosols over the eastern United States. As a first step, we are used measurements from Harvard Forest, a northern mid-latitude forest, and process-level stomatal conductance models to advance the understanding of temporal variability in vegetative uptake of ozone, an air pollutant and greenhouse gas. By coupling dry deposition in a chemistry-climate model with a dynamic vegetation model that includes land-use transitions, combined with an analysis of surface sites and aircraft data, we are examining variability in the dry depositional sink on time scales ranging from hours to decades, including during extreme climate and pollution events. [NSF Graduate Research Fellowship to Olivia Clifton; NOAA]
Isoprene oxidation chemistry, and its resulting impacts on atmospheric chemistry and air pollution, depends strongly on NOx. We examined the potential for combined analysis of trace gas columns retrieved from space-based instruments to provide information on the spatial and temporal variability of isoprene oxidation (as well as methane and other volatile organic compounds). Link to our paper on the role of OH in interpreting variability in formaldehyde columns over the Southeast US. [NOAA Postdoctoral Fellowship to Luke Valin 2013-2015]