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Journal Article: BibTeX citation key:  Bain2011a
Bain, C., Parker, D. J., Dixon, N., Fink, A. H., Taylor, C. M., Brooks, B. & Milton, S. F. (2011) Anatomy of an observed African easterly wave in July 2006. IN Quarterly Journal of the Royal Meteorological Society, 137. 923–933.
Added by: Andreas Fink 2011-04-19 18:05:58    Last Edited by: Andreas Fink 2011-09-14 15:05:32
Categories: General
Creators: Bain, Brooks, Dixon, Fink, Milton, Parker, Taylor
Collection: Quarterly Journal of the Royal Meteorological Society

Peer reviewed
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The detailed structure of an African easterly wave (AEW) observed during the
AMMA field campaign is analysed. The wave was present from 25 to 29 July 2006. A
complex circulation pattern was observed: the overall structure of convection and
the positive vorticity of the trough region had an elongated inverted-V appearance,
wrapped around an area of low winds and clear skies. Satellite imagery showed that
the AEW was a significant influence on the modulation of convection on the large
The wave was identified initially through its strong signature on soil moisture
and convection. The AEW structure observed was not anticipated and has not
been discussed in previous literature. In addition, wave tracking using a Hovm¨oller
diagram of meridional winds did not detect the wave, and a Hovm¨oller of vorticity
showed the wave moved at a slower speed than other AEWs in July.
New schematics explaining the structure are presented, describing the case as
observed by satellites and analysed by a limited-area version of the Met Office
Unified Model. It is proposed that the positive vorticity branches of the inverted-V
can be regarded as analogous to atmospheric fronts, with characteristic gradients in
winds and thermodynamic properties, acting as locations for enhanced convection.
The implications of the new case are discussed in relation to previous theory and
it is suggested that the accepted model of an idealised AEW is incomplete and
should be extended to include more complex structures.
Added by: Andreas Fink    Last Edited by: Andreas Fink