Non-Refractory Submicron Aerosol Chemical Composition during the 2023 AEROMMA Project

The urban portion of the NOAA Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) project occurred during the summer of 2023 over three major cities in the United States (New York City, Chicago, and Los Angeles) to examine their atmospheric emissions and short-term chemical evolution downwind. As part of the project, a suite of instruments for aerosol and gas phase species was deployed on the NASA DC8 aircraft. Here we present preliminary observations of the non-refractory submicron aerosol chemical composition, including comparing the general characteristics of each city. One of the defining aspects of the East Coast air masses sampled was that aged biomass burning aerosols were prevalent. Enhancements in urban aerosol downwind were sometimes on top of a relatively high background, making it difficult to distinguish an urban signature. This is in contrast with individual gas phase compounds with distinct characteristics of sources. Another interesting aspect of this dataset is the observation of varying aerosol composition as a function of altitude in several locations. Lastly, the preliminary findings of this project will be compared broadly with the results from earlier airborne studies.