Using KORUS-OC Observations for a Feasibility Study on Using Satellite- & Ground-based Data for Offshore Air Quality Monitoring

The Outer Continental Shelf Lands Act (OCSLA) requires the Bureau of Ocean Energy Management (BOEM) to ensure compliance with the National Ambient Air Quality Standard so that OCS oil and gas (O&G) exploration, development, & production do not significantly impact the air quality of any state. NASA is supporting BOEM by evaluating the potential for satellite- and ground-based data to monitor offshore air quality over the Gulf of Mexico (GOM), currently the most concentrated region of O&G activity. In this feasibility study, Satellite Continental and Oceanic Atmospheric Pollution Experiment (SCOAPE), we mine data from recent ocean campaigns that are relevant for BOEM's goals and an upcoming GOM SCOAPE cruise. We present examples from a coastal dataset, the Korea-United States Ocean Color (KORUS-OC) cruise, where in situ, satellite- and ground-based column density observations of ozone and NO₂ are compared offshore and at water-land boundaries. The ship measurements are from the R/V Onnuri in May-June 2016;total column data are from OMI and the ship-based Pandora Spectrometer Instrument (PSI). To understand the limitations for using column observations for monitoring air quality over open water and coastal environments, we examine the correlation between surface and column ship concentrations and the influences affecting observed mismatches during KORUS-OC. Three contrasting case studies show how varying meteorological conditions affect the surface-column NO₂ relationship in particular. Our results indicate that vertical stability is vital to a remote sensor's capability (whether ground- or satellite-based) to observe elevated NO₂ that can be linked to conditions near the surface.