Impact of climate variability modes on trend and interannual variability of sea level near the West African coast

• Published in: African Journal of Environmental Science and Technology
• Main Authors: Dièye, A., Sow, B.A., Dieng, H.B., Marchesiello, Patrick, Descroix, Luc
• Other Authors: Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Patrimoines locaux, Environnement et Globalisation (PALOC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: AFRIQUE DE L'OUEST; ATLANTIQUE; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.science/hal-04387897; https://doi.org/10.5897/AJEST2022.3173

The main objectives of this study are to assess the regional distribution of sea level in terms of trend and interannual varibility and to analyze the impacts of climate variability modes such as El Niño-Southern Oscillation (ENSO) events, Tropical Atlantic Climate Modes of Variability (TACMV), North Atlantic Oscillation (NAO) on interannual variability and trend of sea level near the West Africanscoasts. Indices associated with these phenomena are from the National Oceanic and Atmosphere Administration (NOAA), the Global Mean Sea Level (GMSL) time series provided by AVISO (ArchivingValidation and Interpretation Satellite Oceanographic Center) and the Regional Mean Sea Level (RMSL) gridded data by CMEMS (Copernicus Marine Environment Monitoring Service). The results show thatthe mean regional trend of sea level is similar to the global one but the time evolution at interannual and decadal scales does not follow the pattern of global sea level. Our analysis suggests an influence ofENSO events in the Atlantic coast of West Africa. In particular, we observed negative RMSL anomalies during the two strongest El Niño events (1997-1998 and 2015) and a strong positive RMSL anomalyduring the La Niña event of 2011 (the strongest over the last two decades). The analysis also reveals an influence of TACMV and NAO on the interannual sea level variability, essentially through regional SeaSurface Temperature (SST) changes. The study shows that a time series of at least 10 years is required to estimate the trend in sea level rise in West Africa. Sub-decadal trends, primarily reflect naturalclimate modes, rather than variations in climate change. This study also shows that the distribution of sea level rise in the West African region is heterogeneous with higher values near the coast of WestAfrica and near the equator.