Investigating the Impact of Marine Ship Emissions on Regional Air Quality using OMI Satellite NO2 Observations and the CMAQ Model

Commercial marine vessels (CMVs) emit significant amounts of NOx, an ozone precursor, which may contribute to negative health consequences for people living in areas near shipping lanes. In coastal US states, many metropolitan areas such as Baltimore and New York City are located near ports with CMVs. Many studies estimate that ships account for ~15-30% of the global anthropogenic NOx emissions. EPA developed emissions inventories are widely used by states to construct model scenarios for testing air quality attainment strategies. Currently, CMV emissions are generated by simply applying growth factors to aggregated emissions data from much earlier years. Satellite retrievals from the Ozone Monitoring Instrument (OMI) have been successfully used to improve the veracity of marine emissions by incorporating observational data from the inventory year. In this study we use OMI NO2 observations and Community Multiscale Air Quality (CMAQ) model outputs to improve the EPA marine emission estimates for the Mid-Atlantic region. Back trajectories from the NOAA Air Resources Laboratory HYSPLIT model are used to identify days with minimal continental influence on OMI tropospheric column NO2 over shipping lanes. We perform sensitivity analyses to quantify the impact of marine emissions on air quality and suggest strategies to better meet the EPA mandated ozone standard.