**The Energetics of the African Easterly Wave Life Cycle: A Case Study

The life cycle of midlatitude cyclones has been the subject of numerous studies. Easterly waves are, to some extent, their tropical counterparts. However, there have been very few studies about the life cycle of tropical easterly waves. The current description of their life cycle comes from the compilation of the results of various numerical and observational studies. African easterly waves form over central Africa. They reach their peak intensity in the vicinity of the western African coast and then weaken as they cross the central Atlantic. Generally, they dissipate over the western Atlantic Ocean, the Caribbean Sea or the Gulf of Mexico.

NCEP/NCAR reanalysis data will be used to quantify the energetics of the life cycle of an African easterly wave episode that occurred during the late summer of 1999. From the 850 mb relative vorticity perturbation at the trough location, five distinct stages of development have been identified for this specific case. These are: (1) development over Africa, (2) maximum intensity over the west coast of Africa, (3) weakened steady state over the Atlantic Ocean, (4) reintensification over the Caribbean region and (5) dissipation over the western Caribbean-Gulf of Mexico. A compositing technique will be applied to filtered meteorological variables to produce average structure and energetics for each stage of development of the wave. Vertically averaged and level by level energy budgets will then be calculated for each stage.

This work will be expanded in the future to produce a comprehensive picture of the energetics of the life cycle of easterly waves.