Observing Severe Drought Influences on Ozone Air Pollution in California

Abstract

Drought conditions affect ozone air quality, potentially altering multiple terms in the O 3 mass balance equation. Here, we present a multiyear observational analysis using data collected before, during, and after the record-breaking California drought (2011−2015) at the O 3 -polluted locations of Fresno and Bakersfield near the Sierra Nevada foothills. We separately assess drought influences on O 3 chemical production (PO 3 ) from O 3 concentration. We show that isoprene concentrations, which are a source of O 3 -forming organic reactivity, were relatively insensitive to early drought conditions but decreased by more than 50% during the most severe drought years (2014−2015), with recovery a function of location. We find drought− isoprene effects are temperature-dependent, even after accounting for changes in leaf area, consistent with laboratory studies but not previously observed at landscape scales with atmospheric observations. Drought-driven decreases in organic reactivity are contemporaneous with a change in dominant oxidation mechanism, with PO 3 becoming more NO x -suppressed, leading to a decrease in PO 3 of ∼20%. We infer reductions in atmospheric O 3 loss of ∼15% during the most severe drought period, consistent with past observations of decreases in O 3 uptake by plants. We consider drought-related trends in O 3 variability on synoptic time scales by analyzing statistics of multiday high-O 3 events. We discuss implications for regulating O 3 air pollution in California and other locations under more prevalent drought conditions.

The Impact of Climate Change on Mental Health: A Systematic Descriptive Review

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Drought: Progress in broadening its understanding

“…Similarly, anthropogenic activities have increased drought termination phases in the Anthropocene, leading to further consequences of drought impacts (Margariti et al, ). Specifically, in California, the severe 2011–2015 drought affected ozone air quality by potentially altering the ozone‐forming organic reactivities, which showed a decrease by more than 50%, and influenced ozone air pollution (Demetillo et al, ). Compared to the 1.5 K Paris target, an increase of 3 K increases the drought area by 40%, affecting up to 42% of the European population (Samaniego et al, ).…”

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

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