Seasonality of Internal Tide Dynamics in the Senegalo-Mauritanian Upwelling Regions

The seasonal evolution of the M2 internal tide (IT) in the Senegalo–Mauritanian Upwelling Region is investigated using three years (2014–2016) of ocean simulations. The results reveal pronounced seasonal variability in M2 IT dynamics north and south of Dakar, primarily driven by seasonal stratification and remotely generated ITs propagating from the Cape Verde area (CVA). Seasonal stratification strongly modulates local tide-topography interactions, with stratification during the downwelling season (months 9-12) beneficial to IT generation. In the South Dakar area (SDA), local IT generation and dissipation co-vary seasonally, featuring an IT energy source. However, the seasonal dissipation is not directly linked to local generation in the North Dakar area (NDA). This contrasting seasonality suggests a strong influence of remotely generated IT from the CVA, which can seasonally penetrate onshore into the NDA, leading to enhanced dissipation during the upwelling season (months 1-4), and reduced dissipation during the relaxation season (months 5-8). Besides, interannual IT variabilities, mesoscale eddies, and seasonal circulation can further complicate the interpretation of coastal seasonal variability. These results highlight the combined effects of seasonal stratification, circulation, and remote IT propagation, playing a crucial role in modulating coastal IT dissipation and mixing across the Senegalo-Mauritania Upwelling Region.