Satellite NO₂ Trends and Hotspots over Offshore Oil and Gas Operations in the Gulf of Mexico

Abstract

The Outer Continental Shelf of the Gulf of Mexico (GOM) is populated with numerous oil and natural gas (ONG) platforms which produce NOₓ (NOₓ = NO + NO₂), a major component of air pollution. The Bureau of Ocean Energy Management (BOEM) is mandated to ensure that the air quality of coastal states is not degraded by these emissions. As part of a NASABOEM collaboration, we conducted a satellite data-based analysis of nitrogen dioxide (NO₂) patterns and trends in the GOM. Data from the OMI and TROPOMI sensors were used to obtain 18+ year records of tropospheric column (TrC) NO₂ in three GOM regions: 1) Houston urban area, 2) near shore area off the Louisiana coast, and a 3) deepwater area off the Louisiana coast. The 2004-2022 time series show a decreasing trend for the urban (-0.027 DU/decade) and near shore (-0.0022 DU/decade) areas, and an increasing trend (0.0019 DU/decade) for the deepwater area. MERRA-2 wind and TROPOMI NO₂ data were used to reveal several NO₂ hotspots (up to 25% above background values) under calm wind conditions near individual platforms. The NO₂ signals from these deepwater platforms and the high density of shallow water platforms closer to shore were confirmed by TrC NO₂ anomalies of up to 10%, taking into account the monthly TrC NO₂ climatology over the GOM. The results presented in this study establish a baseline for future estimates of emissions from the ONG hotspots and provide a methodology for analyzing NO₂ measurements from the new geostationary TEMPO instrument.