Study of the Vertical Oceanic Pump in mesoscale eddies
This project will study the dynamics/kinematics of the ageostrophic secondary circulation (ASC) and mixing in surface mesoscale anticyclonic eddies and how they modulate plankton activity, plankton community structure, and accumulation and downward transport of organic matter (the Vertical Oceanic Pump, VOP). For this purpose we will conduct a novel interdisciplinary sampling strategy to survey an anticyclonic eddy from a Lagrangian perspective with a resolution down to the submesoscale range using cutting-edge instrumentation and methodologies. We will pay particular attention to the control of the ASC by eddy/wind interaction, by mixing, and by current/wind interaction and frontogenesis/frontolysis at its periphery. ASC will be diagnosed from trajectories of drifters drogued at the Ekman layer and at the eddy´s interior and using an omega-type equation that will include direct measurements of mixing/turbulence. Mixing regime, dynamic stability and vertical diffusion of tracers will be observed and derived from direct measurement of mixing/turbulence. Near-inertial waves trapping and its role in driving shear mixing will be studied from drifter trajectories and from the vertical variability of the horizontal velocity field. To establish the dynamics that forces the VOP we will also develop processes-oriented models and implement regional physical and physical-biogeochemical models for the Canary Region. We will also take advantage of the exceptional source of tracer provided by the El Hierro Island submarine volcanic eruption for the study of eddy submesoscale spatial-temporal variability, combining satellite images and modeling. Finally the physical and biogeochemical observations and processes will be combined and correlated to derive a conceptual model of the dynamics of the marine system linked to the VOP in mesoscale eddies.