Harvard EPA-ACE Center GEOS-Chem Model Output, 2000-2017

This dataset contains North American surface and vertical air quality outputs from the GEOS-Chem global 3-D chemical transport model. We conducted a 2000-2017 simulation with GEOS-Chem model version 11-02c (http://www.geos-chem.org) using NASA MERRA-2 assimilated meteorological data (Gelaro et al., 2017). We use the nested North American version of GEOS-Chem at the native MERRA-2 0.5°x0.625° horizontal resolution over North America and adjacent oceans (10–70°N, 140–40°W) with dynamic boundary conditions from a global simulation with 4°x5°horizontal resolution. The simulation includes detailed NOx-hydrocarbon–aerosol chemistry as described in Travis et al. (2016), Fisher et al. (2016) and Marais et al. (2016). US anthropogenic emissions are distributed spatially following the NEI2011 inventory (EPA, 2018). NEI2011 is scaled for individual years using national annual totals (EPA, 2018), and we decrease non-EGU NOx emissions by 60%, as in Travis et al. (2016), for all years. Open fire emissions are from the daily Quick Fire Emissions Database (QFED; Darmenov and da Silva, 2013) with diurnal variability from the Western Regional Air Partnership (Air Sciences, 2005). Soil NOx emissions, including emissions from fertilizer application, are computed according to Hudman et al. (2012), with a 50% reduction in the midwestern US for summertime based on a previous comparison with OMI NO2 observations (Vinken et al., 2014). Lightning NOx emissions are described by Murray et al. (2012) with a horizontal distribution matching climatological observations of lightning flashes, interannual variability driven by MERRA-2 convection, and most of the release at the top of convective updrafts (Ott et al., 2010). The NOx yield per flash is 260 mol to the south of 35°N and 500 mol to the north (Hudman et al., 2007; Huntrieser et al., 2008, 2009; Ott et al., 2010; Travis et al., 2016)