Dust transport · Iberia and western Europe
The day Spain's sky turned brown
On 15 March 2022 Spaniards woke to a brown, murky sky and cars coated in mud. Storm Celia, a low stalled west of Portugal, was drawing a river of Saharan air north across Morocco and Algeria. The dust covered Iberia, crossed France and reached the Alps; in south-eastern Spain particle levels broke every record since measurements began.
14–17 March 2022 · Spain, France, the Alps · CAMS, ERA5
1.00
Dust optical depth, Madrid, 16 Mar
CAMS, nearest grid point. The March mean there is 0.028.
65µg m⁻³
Surface PM2.5, Madrid, 15 Mar
CAMS daily mean, against a March normal of 14. The WHO 24-hour guideline is 15.G1
3,100µg m⁻³
Daily PM10 in south-east Spain
The highest daily values measured, near Almería, the highest since records began in 2005.S1
Three days of dust
14 Mar
Storm Celia sits west of Portugal. On its eastern side southerly winds lift dust over Morocco and Algeria.
15 Mar
The plume crosses the Mediterranean coast. Southern and central Spain turn brown under the dust.N1
16 Mar
The thickest dust lies over central Spain and France and reaches the Alps. Madrid's optical depth peaks at 1.0.
17 Mar
The low moves away and the air over Iberia clears; a weaker wave returns later in the month.
A low that would not move
Celia was a cut-off low: a pocket of cold air aloft, cut off from the westerlies, which drifts slowly or not at all. Sitting off Portugal for days, it kept a steady south-to-north flow on its eastern side, from the Sahara over the Alboran Sea into Spain. AEMET called the episode extraordinary.N1
A study of recent Saharan intrusions found that such lows, more frequent since 2020, have pushed dust further north over the Atlantic and Europe than before, and that this episode produced the highest PM10 and PM2.5 levels on record in Spain.S1
The air people breathed
In the CAMS reanalysis, surface PM2.5 near Madrid jumped from 7 to 65 µg m⁻³ on 15 March, more than four times the WHO 24-hour guideline.G1 Stations in the south-east, closer to the source, measured far more: daily PM10 between 1,500 and 3,100 µg m⁻³.S1 A grid of reanalysis cells smooths such local peaks.
A month unlike others
×36
Madrid's dust optical depth on 16 March, against the March mean. With a second episode at the end of the month, March 2022 was the dustiest March of 2010–2025 in the CAMS record at both Madrid and Paris.
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References
News
- N1Belgian Science Policy Office, Earth observation. Massive Saharan dust storm affecting western Europe. 17 March 2022.AEMET's assessment and the peak on 15–16 March under Storm Celia.
Studies and guidelines
- S1Cuevas-Agulló, E., et al. (2024). Extreme Saharan dust events expand northward over the Atlantic and Europe, prompting record-breaking PM10 and PM2.5 episodes. Atmospheric Chemistry and Physics, 24, 12031–12053.Record PM10 and PM2.5 in Spain, and the northward spread of Saharan dust.
- G1World Health Organization (2021). WHO global air quality guidelines. Particulate matter, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide.The 24-hour PM2.5 guideline of 15 µg m⁻³.