BOEM is required to analyze the air quality impacts from Outer Continental Shelf (OCS) oil and gas activities as mandated by the Outer Continental Shelf Lands Act (OCSLA) and the National Environmental Policy Act (NEPA). This interagency agreement involves working with the National Aeronautics and Space Administration’s (NASA’s) Atmospheric Chemistry and Dynamics Laboratory at Goddard Space Flight Center to assess the use of satellite data for offshore air quality assessments.
The purpose of this interagency agreement was to conduct a scoping study to assess the applicability of existing satellite datasets for offshore environments and to validate the satellite data with offshore monitoring in a field campaign. The field campaign was conducted primarily aboard the Satellite Coastal and Oceanic Atmospheric Pollution Experiment (SCOAPE) cruise ship. Specifically, this scoping study determined the feasibility of using satellite data in offshore environments in the Gulf of Mexico Region for estimating and monitoring trends of the ground level concentrations of criteria National Ambient Air Quality Standards (NAAQS), precursors, and visibility pollutants.
The final results indicated two air quality "regimes" exist in the Gulf of Mexico Region: (1) clean marine air, when the wind direction is from the south, or ocean-based; and (2) polluted continental air, when the wind direction is from the north, or land-based. In addition, using the TROPOspheric Monitoring Instrument (TROPOMI) NO2 data, Visible Infrared Imaging Radiometer Suite (VIIRS) data, and a HYSPLIT back trajectory model, a flaring event was seen from two oil and gas (O&G) platforms. These data, along with other ground and ship-based Pandora NO2 observations on the cruise, indicate that TROPOMI is useful to BOEM for measuring the Gulf of Mexico and coastal pollution. TROPOMI Total Column NO2 satellite data correlated well with both the coastal and shipboard Pandora spectrometers that provided independent ground truth. Under clean air conditions, satellite-Pandora agreement was 5%; for more polluted conditions, agreement was 15–20%. These results indicate that satellite data can be used for offshore applications. Final reports and collection of monitoring data are posted at https://marinecadastre.gov/espis/#/search/study/100183.
(a) Map of TROPOspheric Monitoring Instrument (TROPOMI) NO2 data on 13 May 2019, during the cleaner portion of the Satellite Coastal and Oceanic Atmospheric Pollution Experiment (SCOAPE) cruise. Shown are the SCOAPE ship cruise track (white line), and the top 200 platform NOx emitters in BOEM’s emissions inventory (white circles). (b) Map of TROPOMI tropospheric column NO2 on 15 May 2019, during the more polluted portion of the cruise. Shown are the SCOAPE ship cruise track (white line), and the top 200 platform NOx emitters in BOEM’s emissions inventory (white circles). (c) Cruise track (black line) with Pandora ship-based observations of total column NO2 (TC NO2) overlaid, showing the cleaner first half of the cruise (blue/green colors), and the more polluted second half (red colors). The top 200 platform NOx emitters in BOEM’s emissions inventory are shown as blue squares. (d) Scatterplot of TROPOMI (white diamonds) and OMI (grey triangles) total column NO2 (TC NO2) comparisons with Pandora during the cruise from both land and ship observations. Agreement is generally within 5%, except during the more polluted period during the cruise from shipboard Pandora observations (blue circle). OMI agreement is slightly better than TROPOMI.