Ocean and Wave Climate Variability in West Africa, and Implications for Alongshore Sediment Transport on the Senegal-Mauritania Coast

Dramé, A.-B.; Burningham, H., and Sall, M., 2024. Ocean and wave climate variability in West Africa, and implications for alongshore sediment transport on the Senegal-Mauritania coast. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 670-674. Charlotte (North Carolina), ISSN 0749-0208. The east Atlantic wave climate in the region of West Africa is dominated by north-northwesterly high energy swell. Wave conditions are variably modified inshore, but a strong obliquity in wave approach remains, leading to a predominance of north-south sediment transport. Implications for coastal sediment movement in the event of deviations or progressive shifts in offshore wave climate are important in driving change in patterns of erosion and deposition. Here, ERA5 wave data covering the last 6 decades (1940-2023) is analysed at annual and seasonal scales to understand the variability in wave climate over time and to explore the association with key climate drivers such as ENSO, NAO, and AMO. The winter season is considered in more detail to investigate extreme wave parameters. Results show that wave height (>2.5m), period (14s) and were more frequent in the 1950s and over the 2000-2018 period, with extreme wave height (3.92m) being associated with a direction of 335.60°. Wave direction increased by 4.08° between 1940 and 2023, which influences sediment transport direction patterns along the coast. NAO has a greater influence on winter swell wave height and direction than ENSO, which only moderately affects the local wave climate.