May 2019 SCOAPE Cruise: Results from 9 Days of Sailing among Oil and Gas Operations in the Gulf of Mexico

The Satellite Coastal and Oceanic Atmospheric Pollution Experiment (SCOAPE) sought to assess the ability of satellite data to monitor air quality near oil and natural gas (ONG) operations in the Gulf of Mexico (GOM). SCOAPE is an Interagency Agreement between NASA and the Bureau of Ocean Energy Management (BOEM – Dept. of Interior), who are required to ensure that ONG operations do not significantly affect the onshore air quality of any State. SCOAPE consists of two major efforts: 1) A formal report outlining the feasibility of using NASA satellite data to monitor air quality in coastal regions with ONG operations, and 2) An air quality cruise in the GOM to validate satellite measurements (primarily NO2) and collect in-situ measurements of emissions from ONG operations. We present results from second portion of the SCOAPE project: the cruise which sailed the GOM from 10-18 May 2019 on the R/V Point Sur. The Point Sur encountered two contrasting air regimes during the cruise: an extremely clean air mass with remote tropical origins when surface O3 was as low as 10 ppbv and NO2 was frequently below 0.5 ppbv, and a more polluted regime with clearly continental origins. This contrast is obvious in the in-situ trace gas and ozonesonde measurements as well as total column NO2 measurements from the Pandora spectrometers on land and on the Point Sur, and was accurately represented in NASA chemical model forecasts. In addition, CH4 (>15 ppmv; CH4 along cruise track and time series in Figure) and volatile organic compound (benzene ~2 ppbv) canister measurements indicate that frequent natural gas leaks at shallow water platforms also have the strong potential to influence air quality over the GOM.