27ATCHEM Atmospheric ammonia measurements at a coastal site along the east coast of the USA

Ammonia (NH₃) is a major atmospheric acid-neutralizing compound that plays an important role in the formation of aerosols which adversely affect human health. Agriculture is the primary anthropogenic source of NH₃ leading to a doubling of reactive nitrogen entering the biosphere. Other sources of NH₃ include industrial processes, vehicular emissions, and volatilization from soils and oceans. Unfortunately, there are limited atmospheric measurements of NH₃ concentrations and fluxes in coastal areas of the Eastern and Mid-Atlantic U.S. Continuous and high temporal resolution measurements of atmospheric NH₃ concentrations along the east coast of the US are needed to provide details of the fluctuations of NH₃ concentrations.

In collaboration with Yale University, scientists and engineers from NOAA conducted ground-based atmospheric NH₃ concentration measurements in 2023 within the Atmospheric Emissions and Reactions Observed from Megacities to Marine Area (AEROMMA) campaign. These measurements were conducted at the Yale Coastal Field Station (YCFS) (Guilford, CT) from April to October 2023.

Continuous and high temporal resolution measurements of atmospheric NH₃ concentrations were measured using the Cavity Ringdown Spectroscopy (CRDS) system, reporting 30 min concentration averages. Micrometeorological measurements were also collected using a meteorological tower installed on the boardwalk at the YCFS. These measurements are very important to characterize the processes that influence the exchanges of NH₃ between the atmosphere and the aquatic surface and provide baseline data to improve air quality model parameterization of NH₃ on a regional scale.