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29.04.2024: online Ocean Circulation and Climate Dynamics Colloquium
Jochen Kämpf, Flinders University, Adelaide, Australia: "On the significance of wind-driven upwelling for the island mass effect"
When? Monday, 29 April 2024 at 11 am
Where? online only via Zoom: https://geomar-de.zoom.us/j/84289388604?pwd=dGlpeTBUd1Nxem5Ec3dRYXh4NFpOUT09
Abstract:
The island mass effect comprises various coupled physical-biogeochemical mechanisms that enhance plankton productivity near an island or groups of islands. This talk presents findings of process-oriented modelling that simulates the wind-driven upwelling process near a reef island using a three-dimensional hydrodynamic model coupled to a nutrient-phytoplankton (NP) model. Findings show that, in the absence of ambient flows, short-lived wind events of 2-5 days in duration, typical of tropical regions, can create significant phytoplankton growth near a reef island due to the classical Ekman upwelling process. The magnitude of this phytoplankton growth depends on several factors including magnitude and duration of the wind event, the size of the island, and static stability of the water column. Additional studies indicate that the wind-driven upwelling process enhances the plankton productivity in the retention zone of island wakes. In this situation, the oscillating flow of the island wake expels patches of upwelled water including its nutrient and phytoplankton loads into the ambient ocean, where it forms floating marine ecosystems. Overall, our studies suggest that the classical wind-driven upwelling process near islands plays a significant role in the functioning of the marine food web in the open ocean.
