Processes in African Monsoon interact
on four spatial scales.
Global scale : this is the scale at which the West African Monsoon interacts with the rest of the globe. Global sea-surface-temperature patterns (such as El Nino) impact the WAM variability, seasonal-to-decadal variability is the main time scales of interest.
Regional scale : this is the scale at which monsoon processes and scale interactions need to be considered and where interactions between the atmosphere, land and tropical Atlantic ocean (especially the Gulf of Guinea) occur. The annual cycle and seasonal-to-interannual variability are the main time scales of interest.
Mesoscale : this is the scale of the typical rain-producing weather systems. This scale is central to the understanding of scale interactions in the WAM system (e.g. through interactions with synoptic easterly waves and the African easterly jet), and the coupling between hydrology and the atmosphere at the catchment scale.
Local scale or sub-meso scale : from an atmospheric point of view, this is the convective rain scale, it is central to the hydrology of the Sahel and of small watersheds to the South. It is the main scale of interest for agriculture and for human impact studies in general.
- African monsoon