Characterizing Extreme Rainfall Types and Flood-Critical Periods in Abidjan, Côte d’Ivoire: A Combined GPM DPR and Historical Rainfall Approach

Extreme precipitation has caused catastrophic flooding across West Africa, worsened by climate change. Understanding which rainfall type (deep, stratiform, or shallow convective) drives flooding along the West African coast can improve disaster response. This study combines seven years (2015–2021) of Global Precipitation Measurement (GPM) Dual-frequency Precipitation Radar (DPR) monthly rain-type retrievals with forty-two years (1984–2025) of in situ daily rainfall observations from SODEXAM at Abidjan. GPM DPR data were aggregated into monthly climatological maps to characterize each rain type’s spatial distribution and seasonal cycle, while SODEXAM daily records were analyzed for rainy-day frequency and depth to identify the flood-critical period. All three types of rainfall contribute to the region’s high seasonal totals, but deep convective rainfall dominates and peaks in May and June, contributing on average 60% of total monthly rainfall versus 35% for stratiform and 5% for shallow convective rainfall. The 42-year ground record showed elevated rainy-day frequency and rainfall depth between 29 May and 18 June, defining a flood-critical period. This period coincides with the climatological peak in GPM-derived deep convective rainfall, indicating that deep convective systems are closely associated with the recurrent severe flooding observed in Abidjan from late May to mid-June.