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Weather and climate in West Africa are determined by the pronounced contrast between tropical, moist air masses over the Gulf of Guinea and the dry desert climate over the Sahara. This contrast results in an atmospheric circulation system which is called "West African monsoon". In the past, the knowledge about the factors that control the monsoon and its strength was limited due to the small number of high-quality observations. Therefore, little is known about the reasons for the significant decline of annual rainfall over the Sahel area during the past 40 years which represents the most pronounced climatic signal worldwide. During the past few years, intensive atmospheric observations were performed in the framework of the international project "African Monsoon Multidisciplinary Analyses" (AMMA) in order to obtain high-quality data and to improve the process understanding. This work gathered and analyzed remote sensing observations which were performed during the AMMA field campaigns, giving new insight into diurnal and annual cycles of atmospheric parameters, such as water vapor, temperature profiles, cloud cover, or wind with a temporal resolution never reached before.

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Bernhard Pospichal is a meteorologist. He received his diplomafrom the University of Vienna in 2005. For his PhD (2009) he wasworking at the Universities of Cologne and Munich as well as inBenin, applying advanced atmospheric remote sensing methods inWest Africa.

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