Understanding Local Dynamics and Air Quality in the New York City Region from Airborne and Ground-based Lidars

Air quality is intimately connected to atmospheric flows, turbulent mixing, and other planetary boundary layer dynamics. While stationary measurements from in situ and profiling instrumentation have a long record of providing insight on the meteorological factors that modulate air quality, observing key processes in hard-to-reach areas such as complex terrain and over water in coastal areas continues to be a challenge. Mobile platforms such as aircraft and ground-based vehicles can provide important new information in these settings.

The NOAA Chemical Sciences Laboratory has developed a state-of-the-art Doppler lidar architecture meant for operation from mobile platforms, providing profiles of winds, turbulent mixing, and attenuated aerosol backscatter above and below an aircraft. This lidar was recently operated during the Coastal Urban Dynamics Study (CUPiDS) from 18 July to 16 August 2023. CUPiDS was designed to study ozone pollution in the New York City area with the NOAA Twin Otter research aircraft, in conjunction with other air quality field studies occurring in the area that summer. The Twin Otter hosted a diverse suite of instrumentation including in situ ozone and NO_x measurements, column NO₂, and the Doppler lidar. The unique coastline and multiple bodies of water (Atlantic Ocean and Long Island Sound) in the New York City area result in spatially varying diurnal flow patterns along with changes in stability and turbulent mixing that complicate local meteorology and air quality. This presentation will show how the airborne Doppler lidar is able to capture the strength of PBL mixing over land versus water and the movement of airmasses laterally and vertically throughout the region, while the other in situ and column measurements tracked the ozone chemistry.

Several ground sites were present for CUPiDS and coincident campaigns (e.g., Synergistic TEMPO Air Quality Science - STAQS) that were strategically located to study the urban pollution transport and evolution, including ozone lidars on the shores of the Long Island Sound. The Doppler lidar data will be used in conjunction with these other datasets to better understand the local dynamics connected to poor air quality days. Good air quality days will be examined as well, including a case where a high-ozone polluted New York City airmass was lifted over the shallow stable layer of Long Island Sound and did not mix down to the surface once advected over land.