Improving Emission Inventories in CESM2.0 Using TOGA Observations from the ATom Campaign

A nebulous understanding of aerosol formation in the most remote free troposphere introduces uncertainties in parameterizations of cloud dynamics, surface albedo and precipitation that snowball in global climate models. Improving emission inventories of precursor gases for natural aerosols is crucial to understanding the origin of predominantly small organic sulfate particles.

We present mixing ratios of volatile organic compounds (VOCs) from the Atmospheric Tomography Mission (ATom-1 and ATom-2) over three ocean basins using the Trace Gas Organic Analyzer (TOGA). Recent laboratory studies at NCAR confirm that TOGA surpasses proton transfer reaction mass spectrometry (PTR-MS) and commercial gas chromatography (GC) instruments with respect to accurate measurements of oxygenated VOCs in low nitrogen oxide (NO) environments, such as methyl vinyl ketone (MVK) and methacrolein (MACR). We use measurements of dimethyl sulfide (DMS), isoprene, MVK and MACR to scale updated “bottom” up emission inventories of DMS and isoprene (Lana et al. 2016; Archer et al. 2009) in CESM2.0 and evaluate the model-observation agreement in vertical profiles and regional distributions using n-fold cross validation. We correlate modeled IEPOX and MSA in CEMS2.0 (in the gas phase) to independent measurements of aerosol composition made on ATom-1 and 2 (IEPOX using the particle analysis by laser mass spectrometer and MSA using the aerosol mass spectrometer) and consider the sensitivity of IEPOX and MSA to aerosol pH and liquid water.