Lagrangian and Eulerian characterization of two counter-rotating submesoscale eddies in a western boundary current

Mantovanelli, Alessandra, Keating, Shane, Wyatt, Lucy R., Roughan, Moninya, and Schaeffer, Amandine (2017) Lagrangian and Eulerian characterization of two counter-rotating submesoscale eddies in a western boundary current. Journal of Geophysical Research: Oceans, 122 (6). pp. 4902-4921.

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Abstract

In recent decades, high-spatial resolution ocean radar and satellite imagery measurements have revealed a complex tangle of submesoscale filaments and eddies, in the surface velocity, temperature, and chlorophyll a fields. We use a suite of high-resolution data to characterize two counter-rotating, short-lived eddies formed at the front between the warm East Australian Current (EAC) and temperate coastal waters (308S, Eastern Australia). In this region, submesoscale filaments and short-lived eddies are dynamically generated and decay at time scales of hours to days. Dominant cyclonic filaments of O(1) Rossby number formed along frontal jets and eddy boundaries, generating localized ageostrophic circulations at the submesoscale. Measurements of over-ocean wind direction and surface currents from high-frequency radars reveal the influence of the short-term, small-scale wind forcing on the surface circulation, enhancement of the horizontal shear, frontal jet destabilization, and the generation and decay of the cyclonic eddy. By contrast, the anticyclonic eddy formation was most likely associated with EAC mesoscale instability and anticyclonic vorticity. Lagrangian tracks show that surface particles can be temporarily trapped in the eddies and frontal convergent zones, limiting their transport. Mixing between EAC-derived and coastal waters was increased along the frontal regions, and particles starting at the divergent regions around the eddies experienced significant dispersion at submesoscales. The cyclonic cold-core eddy entrained high chlorophyll a shelf waters on its convergent side, suggesting spiral eddy cyclogenesis.

Item ID: 50515
Item Type: Article (Research - C1)
ISSN: 2169-9291
Funders: University of New South Wales, Australian Research Council (ARC)
Projects and Grants: ARC CE110001028, ARC DP1093510
Date Deposited: 20 Sep 2017 09:48
FoR Codes: 09 ENGINEERING > 0911 Maritime Engineering > 091103 Ocean Engineering @ 50%
04 EARTH SCIENCES > 0405 Oceanography > 040503 Physical Oceanography @ 50%
SEO Codes: 96 ENVIRONMENT > 9611 Physical and Chemical Conditions of Water > 961104 Physical and Chemical Conditions of Water in Marine Environments @ 50%
96 ENVIRONMENT > 9610 Natural Hazards > 961006 Natural Hazards in Marine Environments @ 50%
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