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New Data Reveals How Storms Are Triggered in the Sahel

ScienceDaily (June 21, 2011)

New Data Reveals How Storms Are Triggered in the Sahel

ScienceDaily (June 21, 2011)

In the Sahel, the frequency of storms increases when soil moisture varies over a few kilometers. Such contrasts cause air circulation between dry and humid areas, contributing to the development of storms. For the first time, these contrasts have been studied on a small scale by a collaboration between French researchers from the Groupe d’Etude de l’Atmosphère Météorologique (CNRS/Météo France) and UK researchers from CEH , as part of the AMMA project.

Their findings, published in the July 2011 issue of Nature Geoscience, provide new data that should help to address the issue of drought in the Sahel.

The Sahel is a semi-arid tropical region where annual rainfall depends on a few dozen storms that form during the monsoon season. The number of storms is therefore crucial in this region of the world, where insufficient precipitation can lead to a year of drought. Intense rainfall during these storms causes marked contrasts with neighboring areas in terms of humidity and temperature. Such contrasts play a role in the stability of the lower layers of the atmosphere.

French researchers from the Groupe d’Etude de l’Atmosphère Météorologique (CNRS/Météo France) and UK researchers from CEH focused on the potential connections between storm formation and variations in soil properties caused by rainfall in the preceding days. They developed a statistical approach to perform individual, daytime analysis of several thousand cases of storm development identified by satellite observations at high spatial and temporal resolution during five monsoon seasons.

Pour en savoir plus (ScienceDaily)

Page publiée le 18 novembre 2011, mise à jour le 2 août 2014