One year on from the big calima in the south of Spain, could the 'Martian' skies happen again?

Although the appearance of large clouds of Saharan sand dust in the skies of the province is something that happens regularly. But, for some time now, when hearing the word 'calima' it makes the people of Malaga’s hair stand on end.

The extraordinary historical event, which left thousands of tonnes of mud on the streets and the facades of buildings, was the result of a cluster of meteorological factors that gave rise to the two main waves, between March 14 and 24 in 2022, that everyone remembers.

25 March 2022: The Costa wakes to red-stained buildings and streets, and another amber alert with more heavy rain to come - in photos and videos

Indeed, the characteristics of the atmosphere mean that it could be repeated in the future, although it is unlikely and therefore the probability that a phenomenon will be repeated could be many years away.

First, looking at an analysis of the meteorological facts. These were collected in detail in a report prepared by Juan Andrés García-Valero, from the state weather agency, Aemet, under the title: “The intrusion of dust of Saharan origin on the Spanish peninsular territory, between the days 14 and March 16, 2022”.

The location of the Iberian Peninsula, relatively close to the Sahara desert, the main reservoir of sand in the northern hemisphere, makes it a region prone to dust intrusions, especially under certain meteorological situations.

The “extraordinary nature” of the event was analysed in the work, with three sections. In the first, a description of the synoptic situation was made the day before and during the days in which the calima occurred. The following shows some observations that show the significant concentration that occurred in the atmosphere and soil. And in the final section this episode is put in context with the results obtained in previous works.

A fatal coincidence of meteorological factors

On 13 March, prior to the start of the dust cloud arriving on the mainland, the weather situation was dominated by two extensive anticyclonic regions, one to the north of the European continent, blocking the Atlantic circulation, and another to the west of the Azores.

Between both anticyclonic systems was a wide depression with a main centre to the west of the British Isles and two other secondary centres, one to the northwest of the peninsula and the other over the Gulf of Leon. Between the Atlantic low pressures and the high pressures to the west of the Azores was a region of strong pressure that generated an intense northwesterly circulation over the North Atlantic.

The trough descended towards the region of the Gulf of Cadiz, and on the 14th gave rise to a cyclo genetic process that led to a high-impact storm named Celia. In tandem, during those days Aemet issued several alerts that warned of widespread and abundant rainfall, as well as the aforementioned intrusion. The trough finally gave rise to an isolated depression at high levels (Dana) in the southwest of the peninsula.

Storm Celia remained stationary until the 15th in the Gulf of Cadiz area, causing strong winds and maritime storms, as well as heavy rainfall in Malaga province. In turn – and this is key – the position of both depression systems to the southwest of the mainland favoured the appearance of an intense circulation from the south over the Sahara region.

The southerly wind in lower layers was intense over areas of the Sahara, where a strong convergence of the wind was also taking place as a result of the storm and the high pressure system that extended over a large part of the Mediterranean and the northeastern area of ​​Africa.

"The wind storm originating in this region of the Sahara and its persistence maintained for more than 24 hours contributed significantly to the immense cloud of dust that invaded the peninsula on the 14th," the scientific report cites. "The instability associated with Celia and its cold front contributed to the dust rising in height, reaching great distances through the circulation at the highest levels."

Yes, it could happen again, but it is unlikely that it will be repeated on a regular basis and with such intensity as last year’s episode. The experts consulted by SUR agree on this, starting with Jesús Riesco, director of the Aemet weather centre in Malaga.

“Normal calimas are very frequent, but I don't remember any of that intensity; Although at Aemet we do not have data on a previous one at this level, the return period of something like this is many years, although we do not know exactly because there is no historical record of a phenomenon of that intensity”.

As can be seen, Jesús Riesco highlighted that the origin was several factors coming together, especially the persistent flow of southwesterly wind in the middle layers of the atmosphere, which carried the mass of dust from the Sahara, previously loaded into the atmosphere by winds. "It was an extraordinary event," he emphasised, not very much in terms of the severity of damage, but in terms of its impact, as it left a multitude of buildings, streets, and furniture stained with mud; to which, for several days, the Martian aspect of the sky was added.

Many of Malaga’s public buildings, still stained brown from the muddy 'calima' rain in March

“If we were to see a situation of this calibre again in the coming years, we would have to worry, because it would be a sign that something new is happening; At the moment, it is a one-off event, which we do not know if it will be repeated again soon”.

Enrique Salvo, a botanist, professor of Plant Biology at Malaga university and an expert on climate change in the province, highlights that to find an event with similar effects, one would have to travel "several centuries back." "Now we have a lot of information, but when I saw those skies I put myself in the minds of those people, who would have thought that this was the end of the world."

However, he believes that the phenomenon could be repeated in the future: “If the heating nuclei of the Saharan surface once again produce convection currents that carry this suspended dust to the upper areas of the atmosphere, and it happens again with intense rains along with southerly winds, we will have this type of event again”. However, he contrasted that the "catastrophe" that occurred from an urban point of view was a blessing for nature, with a "natural fertiliser of nitrogen and phosphates", which greatly favoured vegetation.

José Luis Escudero, head of the SUR weather blog, pointed out that mud drops have always fallen in Malaga, "but a scene like what happened on 14 March, I had never seen in my life." In his opinion, a phenomenon of this magnitude will not be repeated for a long time, and he pointed out that, although the orange skies of the calima haze occur frequently, the difference was marked by the rain: "It rained when there was all that dust around and mud fell; many circumstances have to come together at the same time for that to happen again.”