Lire en Francais Tuareg man on camel in sandstorm in Sahel region near Agadez. - stock photo, Agadez, Agadez, Niger, West Africa, AfricaFrans Lemmens/Corbis Unreleased/Getty Images
More automated weather stations are needed in Africa’s Sahel region to improve understanding of how processes driving wind, rain and dust cause the erosion of Sahelian soils, suggests a new report published in Geophysical Research: Atmospheres.
The semi-arid Sahel region is between the Sahara Desert in the north and tropical savannas in the south covering countries such as Burkina Faso, Cameroun, Mali, Niger and Senegal.
Researchers from Mali, Niger and France observed meteorological parameters and dust concentration for 1,000 rain events while investigating dust emission processes during the rainy season, when Mesoscale Convective Systems (MCS) regularly cross the Sahel. MCS refer to clusters of thunderstorms that occur in the tropics and mid-latitudes, covering thousands of square kilometers and strongly linked to wind speed.
“The Sahelian belt is one of the main sources of mineral dust in the atmosphere. This dust has an effect on climate by absorbing and scattering incident solar radiation,” said Gilles Bergametti, the study’s lead author and research director at Paris-based Interuniversity Laboratory of Atmospheric Systems.
Bergametti calls for an increase in the number of automated weather stations to record all instances of wind at intervals of between 5 and 10 minutes. Current stations record three-hourly, leaving many wind events unrecorded.
The study recorded the highest wind speed during a period between May and June period when the surface has little vegetative matter, leading to the highest observed dust concentration. Additionally, it was observed that strong wind frequently occurs several minutes before onset of rain, allowing a large proportion of dust to be transported into the atmosphere.
Bergametti tells Nature Africa that wind erosion, the driving force behind dust emissions, leads to soil depletion removing the top layer of soil that contains nutrients and organic matter.
