Model of Emissions of Gases and Aerosol from Nature Version 3 (MEGAN3) for Estimating Biogenic Emissions

Abstract

Biogenic volatile organic compound (BVOC) emissions from terrestrial ecosystems drive distributions of several atmospheric constituents relevant to air quality and climate. BVOC emission rates can vary more than an order of magnitude over spatial scales of a few kilometers and time scales of less than a day which makes estimation of these emissions especially challenging. New improvements to the Model of Emission of Gases and Aerosols from Nature (MEGAN version 3) are described including (1) a transparent approach for assigning emission factors and other model parameters, (2) updated emission factors and algorithms based on recent measurements, and (3) treatments for previously unrepresented processes including stress induced emissions and canopy heterogeneity. The estimated emissions are compared to alternative model approaches and evaluated with aircraft measurements of concentrations and fluxes. Remaining gaps and priorities for future progress in biogenic organic emission modeling are also discussed.