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Communication incl. Poster: BibTeX citation key:  Lawa
Law, K. S., Cairo, F., Fierli, F., Schlager, H., Borrman, S., Palazzi, E., Viciani, S., Volk, M. C., Schiller, C., Somé, L., AMMA Burkina & AMMA-SCOUT M55. 2009. Air mass origins influencing the chemical composition of the tropical tropopause layer (TTL) over West Africa. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: Devic 2009-09-08 11:16:25    Last Edited by: roussot 2009-10-19 18:21:18
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Categories: Aerosol and Chemistry, Atmospheric processes, Monsoon system and its variability
Keywords: Chemistry
Creators: AMMA Burkina, AMMA-SCOUT M55, Borrman, Cairo, Fierli, Law, Palazzi, Schiller, Schlager, Somé, Viciani, Volk
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Abstract
An analysis of air mass origins influencing the chemical composition of the tropical tropopause layer (TTL) over West Africa will be presented based on data collected during the AMMA-SCOUT campaign in August 2006. This campaign, based in Ouagadougou, Burkina Faso, collected data on trace gas, aerosol and water vapour distributions between 12 and 20 km using the high altitude research aircraft, the M55-Geophysica. A combination of ensemble back trajectories run for the West African domain and along M55 flight tracks together with information on local convection using MSG images, were used to show that vertical profiles observed over West Africa were influenced by air masses from 3 regions. Local convection over West and eastern Africa influenced profiles up to an altitude of around 355K (150 hPa, 13 km). Evidence for recent (last 10 days) uplift of air masses from Asia was found up to an altitude of 370K (100 hPa, 16 km) transporting both polluted and clean air masses into the TTL. The upper TTL (up to 425 K, 50 hPa, 18 km) was influenced mainly by quasi-isentropic transport from the mid-latitude upper troposphere/ lower stratosphere and was generally associated with air masses with high O3, for example. This picture over West Africa will be contrasted with previous descriptions of the TTL in terms of air mass origin and chemical composition.
Last Edited by: roussot