Sep. 10, 2007 Weather forecasting and climate modelling for the notoriously unpredictable Sahel region of Africa could be made easier in the future, thanks to new research results coming from the African Monsoon Multidisciplinary Analysis study (AMMA).
A paper published in Geophysical Research Letters describes how the AMMA scientists gathered new atmospheric data by using satellite imagery to plot flight paths over areas where storms had produced very wet soils. Dropsondes (weather reconnaissance devices) were launched from a research aircraft above these wet areas to record data such as humidity, wind strength and temperature. The findings allowed the scientists to compare the atmospheric conditions above wet soils with those above adjacent dry soils.
The data showed that temperatures fell by up to 3°C in the air just above the wet soils and also confirmed theoretical studies that predict soil moisture can affect winds. The temperature contrasts between very wet soils and nearby dry soils can have a dramatic effect on weather conditions. Air over wet soils can build up considerable humidity, while the warm air over dry soils rises. When the wet and dry conditions combine, storms are likely to build.
Lead author Chris Taylor from Centre for Ecology and Hydrology said, "Even small patches of moist soils, just ten kilometres across, were found to influence wind patterns. This provides a mechanism where storms can develop in a region because it rained there several days previously."
The results of the study will help climate modellers who have traditionally struggled to accurately represent climate in the region.
Dr Doug Parker from the University of Leeds said, "If we can get it right for West Africa, other parts of the world will automatically benefit."
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