Global High-resolution Emissions for Soil NOx, Biogenic VOCs, and Sea Salt

Natural emissions of air pollutants play major roles in air quality and climate change. In particular, nitrogen oxides (NOx) emitted from soils contribute ~15% of global NOx emissions, biogenic emissions of volatile organic compounds (BVOCs) are the dominant source of VOCs at the global scale, and sea salt aerosols are a major player in the climate and chemistry of the marine atmosphere. These natural emissions are often estimated using nonlinear parameterizations, which are sensitive to the horizontal resolutions of inputted meteorological and ancillary data. The emission estimates at the global scale are typically conducted at relatively low horizontal resolutions (100-400 km). Here we use the Harvard-NASA Emissions Component (HEMCO) to compute soil NOx, biogenic VOCs and sea salt emissions worldwide at horizontal resolutions of 0.625° lon. x 0.5° lat. for 1980-2017 (using MERRA-2 assimilated meteorology) and 0.3125° lon. x 0.25° lat. for 2014-2017 (using GEOS-FP). We further compare these emission results with those calculated at lower resolutions (2.5° lon. x 2° lat. and 5° lon. x 4° lat.) and find significant impacts of resolution on estimated global and regional emissions. The long-term high-resolution emission data here offer useful information to study natural emissions and their impacts on air quality, climate, and carbon cycle.