Intraseasonal variability in easterly wave kinetic energy budgets in west Africa and the east Pacific

Previous studies have documented significant intraseasonal variability (ISV) in easterly wave activity in west Africa and the east Pacific warm pool that may contribute to ISV in tropical cyclone activity. The Madden-Julian oscillation is responsible for some of this ISV in easterly wave activity. We use reanalysis fields and a regional model to examine the perturbation kinetic energy (PKE) and perturbation available potential energy (PAPE) budgets of east Pacific and west African disturbances, including an examination of variability in these budgets on intraseasonal timescales. In west Africa, variability in baroclinic and barotropic energy conversions dominate variability in the energy budgets, including a significant enhancement in baroclinic and baroclinic energy conversions near the entrance to the African easterly jet (AEJ) before west African PKE maximizes. This signal is associated with an eastward extension of the AEJ into this region. Interestingly, diabatic heating anomalies appears to weaken easterly waves downstream in west Africa during periods of enhanced easterly wave activity. In the east Pacific, barotopic energy conversions and diabatic heating serve as the major contributors to ISV in easterly wave activity. We present evidence that convective disturbances in the Bight of Panama serve as precursor disturbances for east Pacific easterly waves, which then grow downstream by barotropic energy conversions and diabatic heating in the east Pacific warm pool.