The impact of drought on surface ozone diurnal variation and trend over the contiguous United States

Abstract:

The US is particularly prone to drought in varying severity, duration, and frequency. Studies have shown that drought can cause the deterioration of ozone air quality during the growing season, but the overall effects of drought on the diurnal pattern and trend of ozone are yet to be quantified. In this study, the two decades (2000-2019) hourly ozone observations and weekly released dryness maps from the US drought monitor (USDM) were used to examine the ozone changes between drought and non-drought at different times of a day. Results show that the drought-induced ozone enhancement can happen at both daytime and nighttime, with a higher magnitude over the eastern US than the western US. The spatial distributions of the enhancement are distinguished from temperature and highly correlated with moisture-related variables. The drought effects on the ozone trend also exhibit strong diurnal and spatial differences. The diurnal variations of ozone to drought can provide insights into the underlying mechanisms of how ozone responds to drought and help mitigate the adverse effects of drought on air quality in a warming climate.