138 Comparison of developing and non-developing African Easterly Waves in high resolution numerical simulations

Thursday, 3 April 2014
Golden Ballroom (Town and Country Resort )
Alan Brammer, SUNY, Albany,, NY; and C. Thorncroft

Developing and non-developing African Easterly Waves (AEWs) are investigated in a large domain 3km grid WRF simulation. These simulations are designed to investigate the role of environmental and wave scale interactions in modulating AEWs over the Eastern Atlantic. The simulations allow detailed convective analysis of MCSs within the trough of the wave, and vortex development in the West African coast region. As suggested by Berry & Thorncroft (2005) and many papers since, convective activity at the coast has been shown to have a significant relation with downstream probability of cyclogenesis. There have been many studies questioning the role of dry air over the Eastern Atlantic with reference to developing tropical disturbances. These simulations also enable high resolution trajectories to investigate the sources and the transport of environmental air into or around the trough. This work will compare two favourable AEWs as they leave the coast with one developing wave and one non-developing wave. The high resolution trajectory analysis will reveal the sources and pathways of air into the trough of the waves in the days after leaving the African coast. Categorising the waves by characteristics as they leave the coast, enables a selection process so that both waves are deemed favourable for developing. The analysis will then highlight how the two waves diverge in the downstream evolution.
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