Short biography:
Marie-Lou Bachelery is a post-doctoral fellow at the University of Cape Town in the framework of the PREFACE project and the Nansen-Tutu Centre. Her research focus on understanding the regional variability of the South-Eastern Atlantic Ocean and the Benguela Upwelling System. In particular, her research apprehends equatorial dynamics and its connection with the coastal variability off the coasts of Angola, Namibia, and South-Africa at the interannual and decadal scale.
Title of the seminar talk: The interannual variability of physical and biogeochemical oceanic properties along the southwestern African coasts: Forcings and low-frequency modulation
Abstract:
Under the influence of South-Atlantic subtropical Anticyclone, coastal southeastern surface wind stress acts as a strong forcing for the oceanic circulation off the coast of Angola, Namibia, and South-Africa creating the upwelling dynamics in the Benguela Upwelling System (BUS). Due to the presence of nutrient-rich sub-surface water in the sunlit layer, the BUS hosts a highly productive ecosystem, detrimental for the food security of the populations of the surrounding countries. However, the regional climate and fish-stock availability are subject to a large variability with regular occurrences (every ~2 years) of extreme warm and cold events called Benguela Niños/Niñas. For a better understanding of the mechanisms associated with these fluctuations and to forecast their occurrences, important research efforts have been devoted to investigate the dynamics of the BUS, its interannual variability and its forcings. In particular, the BUS is connected to the equatorial variability. Part of incoming eastward equatorial wave energy is transmitted southward along the South-African coasts as Coastal Trapped Waves (CTW), where they imprint on the ecosystem variability. At a regional scale, wind events also trigger significant variations of the upwelling intensity and force poleward propagating CTW. This study seeks to enhance understanding about the contribution of the equatorial connection (and CTW propagation) compared with the fluctuation of the local atmospheric forcing (wind stress and heat fluxes) to the physical and the biogeochemical coastal variability. It was led by a need to highlight the dominant processes associated with extreme warm and cold events in the BUS.
Also, in a second part, I will discuss the modulation of the of the interannual event characteristics at low-frequency with a particular interest on the modulation of the remote equatorial ocean dynamics and CTW propagations characteristics along the West African coast.
Arranged date for the seminar talk: June 21, 2018 , 10:15-11:30