Evaluating How Dry Deposition Influences Eastern U.S. Ozone, Aerosols, and Precursors: Mean Contributions, Uncertainties, and Spatio-Temporal Variability from Weather, Regional Climate and Land Use

Using observations to constrain regional emissions of short-lived climate forcing agents (tropospheric ozone, aerosols, and their precursor gases), such as through inverse modeling or adjoint methods, requires quantitatively accurate estimates of sinks. The aim of the project is to investigate the role of an important loss pathway, dry deposition, including specific dry deposition pathways (stomatal versus non-stomatal) and variations with meteorology and land use, in shaping observed distributions of ozone and aerosols over the eastern United States, as well as day-to-day, seasonal, and year-to-year variability. A new approach that involves implementing a mechanistic dry deposition scheme that varies with meteorology and biophysical controls into the NOAA GFDL AM3/LM3 model is being adopted. Combining the new model configuration (AM3- DD) with observations �?? from the summer 2013 NOAA SENEX field campaign, earlier eastern U.S. field campaigns, and ground-based networks and field sites �?? provides an ideal test bed for process-oriented evaluation of the sensitivity of vertical distributions of ozone, aerosol, and their precursors to different representations of dry deposition. AM3- DD will be used to identify constraints on eastern U.S. ozone and aerosol distributions offered by aircraft observations, quantify uncertainties associated with specific dry deposition pathways, and compare directly the role of changing sinks via dry deposition versus changing sources via both anthropogenic and biogenic emissions.