Diabatic Rossby Waves as a Model for Convectively Coupled African Easterly Waves

Monday, 18 April 2016: 10:30 AM
Miramar 1 & 2 (The Condado Hilton Plaza)
James O. H. Russell, North Carolina State Univ., Raleigh, NC; and A. Aiyyer
Manuscript (774.2 kB)

African easterly waves (AEWs) are synoptic-scale disturbances associated with the African Easterly Jet (AEJ) that move westward across the Sahel region of Africa during the West African Monsoon season. It has been shown that the barotropic and baroclinic extraction of energy from the AEJ is not sufficient to sustain AEWs, and that moist convection may have an important role in their maintenance. It is, however, not clear how the synoptic-scale waves and mesoscale convection interact. Furthermore the conditions under which some waves are more closely coupled with convection compared to others is also not well understood. This study examines the hypothesis that convection and AEWs may interact through the Diabatic Rossby Wave (DRW) mechanism. We examine whether the conditions for DRW genesis, a preconditioning of the low-levels ahead of a wave trough, and the generation of potential vorticity (PV) due to the vertical gradient of diabatic heating produced by convection, occur in AEWs. The impact of diabatic PV generation on the amplification, propagation, and evolution of AEWs will be examined through PV and energy budgets calculated using gridded reanalysis and satellite derived products. Results from this will motivate numerical simulations using the weather research and forecasting (WRF) model to further examine the sensitivity of AEWs to moist convection.
- Indicates paper has been withdrawn from meeting
- Submission entered in competition