Vertical Profiles of Ozone Concentrations in the Lower Troposphere
Downwind of New York City during LISTOS 2018-2019
Abstract
Twenty-six balloon-borne ozonesondes were launched near the north shore
of central Long Island in the summers of 2018 and 2019 as part of the
Long Island Sound Tropospheric Ozone Study (LISTOS). While surface
concentrations of ozone are routinely monitored, ozone aloft is
infrequently measured, but critical for a full understanding of ozone
production and transport. Special attention is given to the lower
troposphere from the surface to about 2 km altitude. The observed
vertical ozone profiles are presented and analyzed with additional data
sources and modeling tools, including LiDAR wind profiles from the New
York State Mesonet, back trajectories based on 3 km resolution
High-Resolution Rapid Refresh (HRRR) model data, and surface data,
aircraft observations, sonde, and ozone LiDAR measurements from other
LISTOS participants. The cases analyzed in detail illustrate events with
high observed ozone, often with pronounced vertical structure in the
profile. Specifically, easily discernable layers are identified with
ozone excursions of up to 40 ppbv over short vertical distances. The
analysis indicates that meteorological processes can combine to generate
the observed vertical profiles. Hot, sunny days with high pressure
systems are accompanied by high precursor emissions due to increased
power demands, plentiful radiation for photochemistry, and stagnation of
synoptic winds. These in turn allow shearing due to meso- and smaller
scale flows like low level jets and sea-breeze/shore-breeze circulation
to become dominant and produce the complex vertical layered structure
observed. The five cases presented illustrate these processes.