Stratospheric impacts on dust transport and air pollution in West Africa and the Eastern Mediterranean.

Dai, Ying; Hitchcock, Peter; Mahowald, Natalie M; Domeisen, Daniela I V; Hamilton, Douglas S; Li, Longlei; Marticorena, Beatrice; Kanakidou, Maria et al. · Nat Commun · 2022

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Abstract

Saharan dust intrusions strongly impact Atlantic and Mediterranean coastal regions. Today, most operational dust forecasts extend only 2-5 days. Here we show that on timescales of weeks to months, North African dust emission and transport are impacted by sudden stratospheric warmings (SSWs), which establish a negative North Atlantic Oscillation-like surface signal. Chemical transport models show a large-scale dipolar dust response to SSWs, with the burden in the Eastern Mediterranean enhanced up to 30% and a corresponding reduction in West Africa. Observations of inhalable particulate (PM<sub>10</sub>) concentrations and aerosol optical depth confirm this dipole. On average, a single SSW causes 680-2460 additional premature deaths in the Eastern Mediterranean and prevents 1180-2040 premature deaths in West Africa from exposure to dust-source fine particulate (PM<sub>2.5</sub>). Currently, SSWs are predictable 1-2 weeks in advance. Altogether, the stratosphere represents an important source of subseasonal predictability for air quality over West Africa and the Eastern Mediterranean.

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