Spatial Variation of Surface O 3 Responses to Drought Over the Contiguous United States During Summertime: Role of Precursor Emissions and Ozone Chemistry Journal of Geophysical Research: Atmospheres

Drought is an extreme weather and climate event that has been shown to cause the worsening of ozone (O3) air pollution. Using 15-year (2005–2019) surface O3 observations and weekly US Drought Monitor (USDM) indices, this study estimated that summertime US-mean surface O3 increased by 1.47 ppb per USDM level. It is revealed that O3 responses to drought display a spatial east-west variation: higher O3 enhancement in the Southeast (2.24 ppb/USDM), and no significant change or even a decrease in the west (e.g., −0.06 ppb/ USDM in California). The diurnal changes of O3 with drought also show an opposite pattern between the Southeast and California. Formaldehyde (HCHO) and nitrogen dioxide (NO2) column, two satellite-based Grant no. NA19OAR4310177