Satellite NO2 Trends (2005-2022) and Hotspots over Offshore Oil and Gas Operations in the Gulf of Mexico

The Outer Continental Shelf of the Gulf of Mexico (GOM) is populated with numerous oil and natural gas (ONG) platforms which produce NO_x (NO_x = 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 NASA-BOEM 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 and near shore areas, and a small increasing trend for the deepwater area. MERRA-2 winds and TROPOMI NO₂ data were used to reveal several NO₂ hotspots (5-25% 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. Emission estimates from these hotspots will be obtained using a method that is independent of chemical transfer models and incorporates satellite-observed column amounts along with meteorological reanalysis data. The results presented will be instrumental in validating BOEM’s inventories and provide a baseline for continued monitoring of ONG hotspots with the new geostationary TEMPO instrument.