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International Journal of Geophysics
Volume 2012, Article ID 153256, 14 pages
Research Article

Observations of an 11 September Sahelian Squall Line and Saharan Air Layer Outbreak during NAMMA-06

1Program in Atmospheric Sciences, Howard University, Washington, DC 20059, USA
2NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
3Atmospheric Science Group, Department of Geosciences, Texas Tech University, Lubbuck, TX 79409, USA
4Earth Resources Technology, Inc., Laurel, MD 20707, USA
5Laboratory of Atmospheric Physics—Simeon Fongong, Cheikh Anta Diop University, Dakar, Senegal
6Rosenstiel School of Marine and Atmospheric Science, Cooperative Institute for Marine and Atmospheric Science Studies, University of Miami, Miami, FL 33149, USA
7Environmental Protection Agency, Region 4, Atlanta, GA 30303, USA
8Department of Mechanical Engineering, Howard University, Washington, DC 20059, USA
9Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA 94720, USA
10Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22903, USA

Received 16 April 2011; Revised 28 September 2011; Accepted 5 November 2011

Academic Editor: Alessandra Giannini

Copyright © 2012 J. W. Smith et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The 2006 NASA-African Monsoon Multidisciplinary Analyses (NAMMA-06) field campaign examined a compact, low-level vortex embedded in the trough of an AEW between 9–12 September. The vortex triggered a squall line (SL) in southeastern Senegal in the early morning of 11 September and became Tropical Depression 8 on 12 September. During this period, there was a Saharan Air Layer (SAL) outbreak in northwestern Senegal and adjacent Atlantic Ocean waters in the proximity of the SL. Increases in aerosol optical thicknesses in Mbour, Senegal, high dewpoint depressions observed in the Kawsara and Dakar rawinsondes, and model back-trajectories suggest the SAL exists. The close proximity of this and SL suggests interaction through dust entrainment and precipitation invigoration.