Meteorological Influences on Surface Ozone in the Houston-Galveston-Brazoria Region

Varying meteorology within the complex coastal subtropical environment of the Houston-

Galveston-Brazoria (HGB) region has emerged as a driving factor of surface ozone

concentrations, which are harmful to human health. Thus, analysis of ozone trends around

common meteorological events as well as routine collection of air quality data in unmonitored

over water areas drives a more complete understanding of the influence meteorology has on

high ozone events in the HGB region.

Chapter 1 describes the deployment of three boats outfitted with ozone and

meteorological instruments to the Gulf of Mexico and Galveston Bay for the Galveston

Offshore Ozone Observations (GO3) and Tracking Aerosol Convection Interactions

ExpeRiment - Air Quality (TRACER-AQ) field campaigns from July-October of 2021 to

address the observational gap in over water air quality data needed to verify and improve

photochemical modeling. During these campaigns, over 600 mobile hours were logged

including 134 missions and 35 ozonesondes launched throughout Galveston Bay and the Gulf

of Mexico. Several periods of ozone exceeding 100 ppbv were observed over the waters of

Galveston Bay and the Gulf of Mexico during the operational period.

Chapter 2 examines the relationship between mesoscale circulations and surface ozone

in the HGB area between 2020-2022. The HGB area was found to have a strong correlation

between mesoscale circulations and maximum daily 8-hour (MDA8) ozone exceedance days

with 91% of exceedance days exhibiting a bay breeze or mesoscale induced storm.

Additionally, a unique feature of rapid ozone enhancement coincident with the passage of

mesoscale boundaries was analyzed.

Chapter 3 discusses the development of a novel method for clustering North Atlantic

tropical cyclones (TC) from 2010-2021 using a k-means algorithm for the purpose of relating

the time-period around the landfall of a TC in North America to MDA8 ozone exceedances in

the HGB area. Landfall locations along the east coast of the United States were found to

produce the highest MDA8 ozone values in the HGB area, with an average maximum MDA8

ozone value in the region of 101 ppbv in the 0-2 day period after landfall.