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Communication incl. Poster: BibTeX citation key:  Barthe
Barthe, C., Asencio, N., Lafore, J.-P., Chong, M. & Campistron, B. 2009. Comparison between Doppler radar observations and cloud-resolving simulations: multi-scale analysis of the 25-27 July 2006 convective period over Niamey. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: roussot 2009-11-04 19:02:38
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Categories: Atmospheric processes, Monsoon system and its variability, Weather to Climatic modelling and forecasting
Keywords: Atmospheric Boundary Layer, Clouds - Convection
Creators: Asencio, Barthe, Campistron, Chong, Lafore
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Abstract
This study analyzes in detail the multi-scale processes associated with a sequence of convective events that occurred over Niamey during the 25-26 July period corresponding to the active stage of the first intense monsoon burst over Sahel in 2006.
Among the large AMMA-SOP dataset, the 3D wind field from the Massachusets Institute of Technology (MIT) Doppler radar is used with a cloud-resolving model to analyse the convection organization and its interaction with the environment.
The high temporal radar observations captured two successive mesoscale convective systems (MCS) followed by a period of isolated convection. Both UHF profiler and MIT radar depicted the 3D-wind structure and the interactions with the convection and the low levels: the two successive systems were located ahead and in phase with the trough of an African Easterly Wave (AEW), while the following suppressed or isolated convection is associated with the ridge.
The simulation succeeds in reproducing these features except the first MCS which is lacking in the initial fields. Within the MCSs, the observed and simulated cross-line circulations fit with the 2D conceptual model of fast moving squall lines. The computation of the apparent source of momentum due to convection suggests that the transport of the along-line component by convection can have a positive feedback on the trough and thus on the AEW.
The local convection on the 26 July afternoon is characterized by a combination of favourable (humidity, CAPE, CIN, vorticity) and inhibiting factors (mid-levels dry layer, low-levels wind shear pointing to the north).
Added by: roussot