Direct Observations of Pollution Gradients within the Chesapeake Bay Watershed: Overview of the Ozone Water–Land Environmental Transition Study-2 (OWLETS-2)

One of the major difficulties for the modeling and satellite communities is the validation of O₃ levels in sharp coastal transition regions within metropolitan areas. Land-water gradients in pollutants can be significant due to differences in emissions (and specific O₃precursors), surface deposition, boundary layer height, and cloud coverage. The Ozone Water-Land Environmental Transition Study (OWLETS-2), was a follow-on field campaign conducted in the summer 2018 within the Upper Chesapeake region to better characterize spatial and vertical distribution of pollutants across the coastal boundary. To quantify these gradients, research instrumentation was deployed directly within the marine environment (Hart Miller Island, HMI) and at a several continental sites (University of Maryland, Baltimore County (UMBC), Howard U. – Beltsville (HUBV)). Regulatory sites within Maryland, operated by the Maryland Department of the Environment (MDE), were also utilized to better characterize pollution levels within the region.

During intensive measurement days, time-synchronized data were collected from ground-based measurements, which included: TOLNet lidars, micro-pulse lidars, ceilometers, radiometers, Doppler wind lidars, ozonesondes, O₃ sensors mounted on mobile platforms (including UAV), Pandora, AERONet, and a diverse set of in situ chemical (trace gas and particulate) measurements. To better infer gradients between the research sites and to provide context for regional analyses, two aircraft and research vessels also contributed to OWLETS-2 as various points during the campaign: the NASA Langley Falcon with the GeoTASO passive remote sensor, the UMD Cessna with an in-situ chemistry analysis suite, and several research vessels with both remote and in-situ sensors. These observations, coupled with reliable chemical transport simulations, are expected to lead to a more fully characterized and complete land-water interaction observing system that can be used to assess future geostationary air quality instruments, such as the NASA Tropospheric Emissions: Monitoring of Pollution (TEMPO) as well as current low earth orbiting instruments such as the European Space Agency’s Sentinel 5-Precursor (S5-P) with its Tropospheric Monitoring Instrument (TROPOMI).