Raquel Flugel

Advisors: Anne Marie Treguier, Steven Herbette, Jennifer Veitch (SAEON), Chris Reason (UCT)

Funding: UBO/ISblue

Start date: 01/10/2022

This Ph.D. work aims to quantify the impact of fine-scale wind variabilities on upwelling dynamics under current and future climate in the Southern Benguela Upwelling System (SBUS). Small scale wind conditions are complex and governed by ocean-atmosphere-interactions through sea surface temperature, and ocean-land-interactions through local topography and the shape of the coast. Key processes include the drop-off of the wind towards the coast, taking effect within 10-80 km offshore from the coast, local wind relaxations triggering retention processes and the diurnal sea breeze. Currently used climate models often fail to represent those small scale features due to their low spatial resolution. However, these local wind variabilities and resulting upwelling dynamics have an important influence on the biological productivity of the system and the development of potentially harmful algae blooms. We therefore aim to use the regional ocean model CROCO (Coastal and Regional Ocean COmmunity) forced by the high-resolution (3 km) WASA (Wind Atlas for South Africa) winds from the CSAG (Climate System Analysis Group) compared to simulations forced with ERA5 and ERA5 with refined coastal winds to identify the response of the upwelling dynamics to the fine-scale winds. The goal is to quantify the impacts of coastal shape, topography and synoptic processes on the drop-off for a better understanding of the current state and to apply this knowledge in the context of global climate change.