Small scale transport processes from HF-Radar
Abstract
Coastal ocean ecosystems are major contributor to the global biogeochemical cycles and biological productivity. Physicalfactors induced by the turbulent flow play a crucial role in regulating marine ecosystem. However, while large scale dynamicsin the open ocean is well described by geostrophy, the role of small scale transport processes in coastal regions is stillpoorly understood due to lack of continuous high-resolution observations. Here, the influence of small-scale coastal dynamicson surface phytoplankton structuring is studied using Lagrangian metrics computed from HF Radar currents and satellitechlorophyll-a (Chl). The combination of complementary Lagrangian diagnostics, including the accumulated divergence of theflow along fluid trajectories, provides an improved description of the 3D flow geometry which facilitates the interpretation of twonon-exclusive physical mechanisms affecting phytoplankton patchiness. Attracting submesoscale fronts, unveiled by backwardsLagrangian Coherent Structures, are associated to negative Lagrangian divergence where particles and Chl standing stockscluster. Filaments of positive Lagrangian divergence, representing large accumulated upward vertical velocities and suggestingaccrued injection of subsurface nutrients, match areas with large Chl concentrations. Our findings demonstrate that an accuratedescription of small-scale transport processes is necessary to comprehend bio-physical interactions in coastal seas and toestimate biological productivity.
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- May 2020
- DOI:
- 10.5194/egusphere-egu2020-6722
- Bibcode:
- 2020EGUGA..22.6722H