View from EOC to the south on 15.3.2022, 14:26 LT, Photo: Stefan Dech
People in Spain, France and southern Germany witnessed a striking weather phenomenon. Desert sand spread northward thanks to a prominent low pressure zone over the northwest African coast that gave the heavens a muddy orange tint. Such occurrences are not unusual, but measurements from satellites and ground-based instruments indicate that this phenomenon is becoming more frequent.
In 2008 there were only four desert sand manifestations, but in 2018 there were already twice as many. Whether or not this increase is indeed systematic, in other words, indicates a basic change in the airstreams, is still a matter of current research. It is noteworthy that the present low pressure system resulted from the cut-off of air masses from the jet stream, which suggests that the jet stream and its associated planetary waves impact on the situation. These large-scale global waves are suspected of modifying their activity as a result of climate change. This, too, continues to be a subject of current research.
The wind flow on March 15, 2022 at an altitude of about five kilometres. Over Africa, the swirl cut off from the jet stream sucks up small desert sand particles (dust) from the ground and hoists them to higher elevations. There they are transported together with the large-scale air flow. If the wind blows from the right direction, this desert dust also reaches us and the sky takes on a yellowish brown colour. (© NullschoolEarth)
This MODIS satellite image mosaic shows the prominent atmospheric desert dust load as a wide brown band. (© DLR/EOC // Data source: MODIS, Terra/Aqua, NASA)