African dust crosses the Atlantic


A beautiful Atlantic sunset off the coast of Florida, or an orange glow in the Texas sky at dusk may be caused by dust from West Africa, say researchers studying the trajectories particles in the sky over the Sahara desert and the semi-arid Sahel.

“We’re looking at how much dust is transported across West Africa in the winter and across the Atlantic in the summer,” said Gregory S. Jenkins, professor of meteorology and atmospheric sciences, geography and African studies, Penn State. “In winter, it is low in the atmosphere and in summer, it is higher in the atmosphere. Dust has an impact, in particular on health.”

Jenkins and Moussa Gueye, teacher-researcher, Université du Sine Saloum El-Hȃdj Ibrahima NIASS, Dakar, Senegal, modeled annual particles below 10 microns (PM10) from 1960 to 2016.

“We showed that there is a simulated annual trend of decreasing surface concentrations of PM10 in Senegal and Cabo Verde after the 1980s, which is similar to previous results,” reports the researcher in Atmospheric Environment. However, data for summers suggest that there was an increase in dust over Western Sahara that was transported to Cabo Verde, suggesting that this eastern Atlantic dust continued to the United States. United and the Caribbean.

Researchers can measure the amounts of dust reaching the western Atlantic near Miami, Barbados and Puerto Rico, for example, because there are many meteorological and other measuring stations in these areas, but in East Africa West and in places like Cabo Verde there are few ground measurement stations. – measuring facilities to measure the dust that reaches it.

Researchers must then rely on satellite measurements, which cannot provide measurements at night. Data collected by ground-based and satellite-based instruments are used as the basis for models that estimate the trajectories and amounts of dust hitting West Africa in winter and the Atlantic and Caribbean in summer. However, there are so few measuring stations in Africa – because stations require electricity, cell phones, internet and someone to maintain them – that the models are somewhat incomplete.

“With the very limited measurements we have of West Africa relative to our measurements, we run the models and provide estimates,” Jenkins said. “We know the timing of the model is correct, but we don’t know how much the few stations we have are skewing our results.”

According to Jenkins, currently the best system is in Nigeria where the stations are 25% cheaper, but they still need reliable electricity and internet. He notes, however, that Cabo Verde has reliable Wi-Fi and that he would like to install particle stations on each of the islands.

According to Jenkins, the model simulations reproduce the trends observed in the past, however, none of the models simulate dust correctly. It is important to know exactly where the dust is going at all times and how much dust exists at ground level. Estimates suggest that West Africa will have a population of one billion by 2070. Because this dust in the air can cause respiratory problems and can carry pathogens, it’s important to know when to stay away from dust.

“The dust will have a big impact in West Africa,” Jenkins said. “But in the United States we also want to know what will happen in the future. I think there are good reasons to say that there will be more dust in the future.”

Jenkins would like to build a particle system across Africa so that there is enough data to refine the models. The system would also be able to warn people with, for example, asthma when they should stay indoors.

One of the researchers’ concerns is that they know this Saharan dust transport could change due to climate change in the future.

The Penn State Alliance for Education, Science, Engineering and Design in Africa supported this work.

Source of the story:

Materials provided by Penn State. Original written by A”ndrea Elyse Messer. Note: Content may be edited for style and length.


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