Abstract:
Daily rainfall data from Ghana Meteorological Agency (GMet) rain
gauge network was analysed to identify extreme rainfall events in Ghana. The
data was first processed in order to remove all errors in the observational time
series prior to analysis. The data was then analysed by excluding all rainfall
events, which fell below a pre-determined threshold in order to identify
extreme rainfall event days and non-extreme event days. Inter-annual
variability and trends of annual precipitation totals in Ghana are analyzed
considering different gridded observational and ERA-Interim re-analysis
products. The spatial and temporal distribution of the different rainfall seasons
(wet and dry) over Ghana was analyzed in the period 1988-2014. The total
annual precipitation as well as extreme precipitation showed a general shift
towards a wet climate in the study area. Most of the variables analysed,
specific humidity and horizontal moisture flux during extreme and nonextreme events showed significant differences. These are the key variables
when describing climatological differences between extremes and nonextremes. The surface specific humidity distribution has relatively higher
values during extreme events than the non-extreme events. The transport of
moisture flux along the boundary layer at 850 hPa shows a more westward
transport in wet seasons. The extreme events are favoured by southwesterly
wind flow and stronger northeasterly winds as compared with the non-extreme
events
