Investigating the formation of submesoscale structures along mesoscale fronts and estimating kinematic quantities using Lagrangian drifters
Date
2020
Authors
Lodise, John
Özgökmen, Tamay
Gonçalves, Rafael C.
Iskandarani, Mohamed
Lund, Björn
Horstmann, Jochen
Poulain, Pierre-Marie
Klymak, Jody
Ryan, Edward H.
Guigand, Cedric
Journal Title
Journal ISSN
Volume Title
Publisher
Fluids
Abstract
Much of the vertical transport near the surface of the ocean, which plays a critical role in the
transport of dissolved nutrients and gases, is thought to be associated with ageostrophic submesoscale
phenomena. Vertical velocities are challenging not only to model accurately, but also to measure
because of how difficult they are to locate in the surface waters of the ocean. Using unique massive
drifter releases during the Lagrangian Submesoscale Experiment (LASER) campaign in the Gulf of
Mexico and the Coherent Lagrangian Pathways from the Surface Ocean to the Interior (CALYPSO)
experiment in the Mediterranean Sea, we investigate the generation of submesoscale structures along
two different mesoscale fronts. We use a novel method to project Lagrangian trajectories to Eulerian
velocity fields, in order to calculate horizontal velocity gradients at the surface, which are used as
a proxy for vertical transport. The velocity reconstruction uses a squared-exponential covariance
function, which characterizes velocity correlations in horizontal space and time, and determines the
scales of variation using the data itself. SST and towed CTD measurements support the findings
revealed by the drifter data. Due to the production of a submesoscale instability eddy in the Gulf
of Mexico, convergence magnitudes of up to ~20 times the planetary vorticity, f , are observed,
the value of which is almost 3 times larger than that found in the mesoscale dominated Western
Mediterranean Sea.
Description
Keywords
mesoscale/submesoscale interaction, kinematics, Lagrangian drifters
Citation
Lodise, J., Özgökmen, T., Gonçalves, R. C., Iskandarani, M., Lund, B., Horstmann, J., . . . Guigand, C. (2020). “Investigating the formation of submesoscale structures along mesoscale fronts and estimating kinematic quantities using Lagrangian drifters.” Fluids, 5(3), 159. https://doi.org/10.3390/fluids5030159