Wind-driven eddies and plankton blooms in the North Atlantic Ocean

Wind-driven eddies and plankton blooms in the North Atlantic Ocean
Technical memorandum
Date Published
Secondary Title
ECMWF Technical Memoranda
C. Eden,
T. Jung,
AbstractRecent high-resolution satellite missions have revealed persistent small-scale features in near surface winds over the global oceans (Liu et al., 2000; Xie et al., 2001; Chelton et al., 2004). Here we report that such features - in contrast to previous belief (Chelton et al., 2004) - also show up in numerical weather prediction models such as the operational high-resolution model of the European Centre for Medium-Range Weather Forecasts (ECMWF). We exploit this finding by forcing a high-resolution general circulation model of the North Atlantic ocean over a 4-year period with surface wind stress and heat fluxes taken from the ECMWF model. Driven by the orographically forced small-scales features in the wind forcing, in our simulation, meso-scale oceanic eddies develop in the lee of Islands located in areas of prevailing trade winds such as the Cape Verde Islands. These eddies can provide a substantial, previously overlooked source of oceanic eddy kinetic energy in subtropical regions. Furthermore, anticlockwise circulating eddies are related to upwelling of nutrient rich water from below leading to large plankton blooms in the simulations. It is speculated that similar eddies also show up at comparable other locations in the world oceans, e.g. the Hawaiian Archipelago, with far-reaching implications for local and basin-wide ecosystem dynamics.