The role of Kelvin wave activity on convection and rainfall over tropical Africa

The climatology and nature of westward propagating convective systems and their association with African easterly waves (AEWs)over tropical West Africa are relatively well known. Observations also show eastward moving convective systems from western tropical Africa towards East Africa. Our knowledge of eastward moving systems in this region, however, is limited. These systems may be associated with eastward moving wave activities, such as Kelvin waves, or they may be steered by occasional mid-latitude troughs that dip into the eastern Africa region. In this study, we will highlight: (i) regions of genesis of Kelvin waves that impact the Sub-Saharan Africa and (ii) the association of the passage of Kelvin waves with the convective initiation/enhancement over eastern Africa. Knowledge of the genesis of the wave activity is important to understand the regional connection and the potential to predictability.

An 18-year satellite observed brightness temperature data and the European Centre for Medium range Weather forecast (ECMWF) reanalysis data sets will be used. Case studies will be presented to illustrate the association between wave activities and convection.