Modeling global fire emissions of organics and their impact on reactivity

Fires are a large source of non-methane organic gas (NMOG) emissions to the global atmosphere. These emissions can contribute to the formation of secondary pollutants such as ozone and particulate matter. However, the abundance and impacts of these emissions are uncertain and historically not well constrained. In this presentation, I will describe recent efforts to expand the representation of NMOGs from fires in a global model (GEOS-Chem) as well as the evaluation of the resulting simulation against airborne observations from the FIREX-AQ and ARCTAS campaigns. We use this expanded model to make the first estimate of the fire contribution to OH reactivity (OHR). We find that fires make an important contribution to global mean surface OHR (15%), and can be a dominant source of reactivity (up to 75%) over fire source regions. This work highlights the importance of representing the emissions and chemical oxidation of the suite of NMOGs emitted from fires in models.