New insights into the atmospheric redox chemistry of mercury (Hg) and terrestrial atmospheric exchange processes have been enabled over the past several years by field and laboratory studies. Recent work has suggested that atmospheric Hg uptake by terrestrial ecosystems may be larger than previously realized and may exert a large influence on seasonality in atmospheric mercury concentrations in some regions and interhemispheric differences in concentration measurements.  We explore this hypothesis using new lab measurements and theoretical rates of elemental Hg (Hg⁰) oxidation in the atmosphere via bromine, chlorine, and hydroxyl radical-initiated mechanisms and theoretical calculations of the species-specific spectra of photolysis cross-sections for atmospherically-relevant Hg(II).We will present implications of these data for modeled concentrations of atmospheric Hg(II) and associated deposition patterns using the GEOS-Chem global CTM, which we compare to global atmospheric measurements. The atmospheric simulation is coupled to an updated version of the Global Terrestrial Mercury Model (GTMM) and used to investigate the significance of different atmospheric-terrestrial exchange processes. Through representation of the internal cycling and retention dynamics of terrestrial Hg, this model provides spatially-resolved insights into ecosystem factors controlling the balance between Hg deposition and re-emission across a range of timescales. We present implications for modeled spatial concentrations of atmospheric and soil mercury across the contiguous United States and compare to available measurements. Implications of improved mechanistic understanding of Hg cycling in the atmospheric and terrestrial ecosystems for the global Hg budget and timescales for cycling of anthropogenic Hg through ecosystems will be discussed.