A vast plume of Saharan dust is about to sweep over France

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From this Sunday and until Tuesday at least, most of the country will be affected by an imposing plume of sand from the Sahara. Although this type of event is not atypical as such, the quantities of dust that will circulate at altitude could reach exceptional levels.

On February 6, under the impetus of a powerful flow from the south, a large part of France suffered the rise of Saharan dust. The latter then dressed the sky in an astonishing ocher to orange hue, as evidenced by the many photographs shared on social networks.

The rains that circulated in this air mass often left typical traces of mud on the bodies and windows. But it is probably in the mountains that the effects have been most exotic. Indeed, the snowpack was covered with a film of sand bringing a Martian landscape for the less spectacular. This was particularly the case in the Pyrenees.

Saharan dust plume: a repeating scenario

Just two weeks later, things seem to want to repeat themselves. And for good reason, the disturbed flow located on the near Atlantic has again shifted very low in latitude – to the south of Morocco. The large dust plume currently present in West Africa will be sucked into the front of the depression and propelled into Scandinavia by a powerful flow from south to southwest. If we consider the quantity of sand mobilized, the expected episode is more important than that of the beginning of the month.

Satellite image of February 19, 2021. Note the atmosphere rich in Saharan dust above and to the west of the Sahara. Credits: EOSDIS worldview.

However, the European atmosphere monitoring service Copernicus indicated that it is not possible to say if the sky will take the same colors. ” We have been monitoring similar events over the past few weeks, with significant impacts on air quality in affected regions »Says Mark Parrington, researcher at Copernicus. ” This has been confirmed by surface measurements collected by the European Environment Agency in various countries. We expect this to be the case for the upcoming event as well, although it is not yet clear how visible the plume will be to the naked eye. “.

Mud rains and reduced air quality

The satellite image above makes it possible to locate the plume of sand located off the Sahara. It is with this wide tank that the disturbed flow connected during its very southern dive. Therefore, the dust concentrations are expected to reach particularly high levels over much of the country Sunday to Tuesday. The animation below illustrates the rise of the Saharan plume between Saturday 4:00 am to Thursday 1:00 am as simulated by the model NASA GEOS-5.

The warmer the colors, the greater the amount of dust. Credits: Météociel.fr.

Over the west and south of the country, some precipitation will circulate in connection with the proximity of the Atlantic disturbance. Also, mud rains are locally expected in these regions. Further to the center and to the northeast, it is almost summery weather that will prevail. However, the presence of a large amount of dust aloft should make the sky milky or hazy – sometimes significantly reducing the impression of good weather.

Finally, let us insist on the quality of the air which will be degraded during this meteorological episode. In particular in the mountains, but all altitudes will be concerned. Fragile people will therefore be particularly exposed. ” High dust concentrations can affect the health of the respiratory system of all persons in affected areas and adds to air pollution by particulate matter from local sources Mark Parrington notes.

The persistence of high pressure conditions over most of Europe will not allow rapid evacuation of dust. It will obviously be necessary to wait until next weekend to find levels similar to those present before the arrival of the plume. To end on a lighter note, if it is not never two without three As the saying goes, this episode might not be the last of the season!





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