Comparisons of Upper Air Ozone Concentrations at Coastal and Urban Sites and the Impacts of Local Urban Greenhouse Gas Emissions

Beginning July 2018, two Electrochemical Concentration Cell (ECC) ozonesondes were simultaneously launched from Half Moon Bay (HMB), CA and San Jose (SJC), CA at approximately 1400 PST (2100 UTC). Additionally, a Los Gatos Research (LGR) greenhouse gas analyzer was used to collect carbon monoxide (CO), carbon dioxide (CO₂), and methane (CH₄) data from the San Jose launch site throughout the campaign. The motivation of this field experiment is to quantify the impact of urban settings on ozone (O₃) concentrations, as well as determine the effects of greenhouse gas emissions on the ozonesonde profile.

Prior studies have suggested that CH₄ can act as an indirect precursor to O₃. Both CO and O₃ have been observed to be highly correlated in the presence of photochemistry. We hypothesized that an increase in greenhouse gas emissions in an urban region will lead to an increase in O₃ concentrations throughout the profile. Thus, HMB was set as the “background O₃” for the purposes of this study. Half Moon Bay is a coastal location and onshore wind conditions were isolated in order to reduce local anthropogenic influences. The SJC profile was then compared to HMB and the differences in concentrations throughout the profile were quantified. A correlation analysis was then performed between these perturbations and the CO, CO₂, and CH₄ data.