Comparison of Atmospheric Ethanol Observations with Model Predictions over Manitou Experimental Forest Observatory
Ethanol in the atmosphere is a precursor of acetaldehyde and peroxyacetyl nitrate, both hazardous air pollutants that adversely affect human health and contribute to ozone pollution. Ethanol is known to have anthropogenic sources, like its use as a fuel additive, and natural sources, as it is emitted by plants. This research aims to compare atmospheric ethanol concentration and fluxes over a forest landscape in the United States with predictions from a chemical transport model (CTM), GEOS-Chem. The GEOS-Chem model is widely used within the atmospheric chemistry community, and is relied upon for accurate representation of compounds in the atmosphere. Evaluating the CTM output is essential to assessing the accuracy of the model predictions. The measurements of ethanol in the atmosphere were recorded at Manitou Experimental Forest Observatory in Colorado by Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry. The analysis of the obtained data was performed using the R programming language. It was determined that the GEOS-Chem CTM is largely underpredicting the fluxes and concentrations of ethanol, as well as missing surface removal of ethanol that is evident in the measured data. These findings call for more investigation into seasonality and sources and sinks of ethanol that exist within forest ecosystems.