Coherence of Eddy Kinetic Energy Variation during Eddy Life Span to Low-Frequency Ageostrophic Energy

Abstract

The evolution of mesoscale eddies is crucial for understanding the ocean energy cascade. In this study, using global reanalysis sea surface velocity data and a mesoscale eddy trajectory product tracked by satellite altimeters, we aimed to reveal the coherence of eddy kinetic energy (EKE) variation to low-frequency ageostrophic energy during the eddy life span. The variation in EKE throughout the eddy life span was highly coherent to that of the seven-day low-passed ageostrophic kinetic energy, with a correlation coefficient of −0.94. The low-frequency ageostrophic motions supplied 38% of the EKE variation in the growing stage of mesoscale eddies and absorbed 42% in the decaying stage. The evolution rate of the EKE during the eddy life span was consistent with the barotropic conversion rate of the low-frequency ageostrophic motions, further confirming the dominant role of low-frequency ageostrophic motions in eddy growth and decay.

Bioluminescent eddies of the World Ocean

“…Orbital speed of eddies gradually exceeds their translation speed. [13,35] Their ratio implies that a certain body mass is trapped in the eddy interior and will be transported. According to model results, the mean eddy retention time of a plankton patch (with a certain BP) is highly variable (from 5 to 67 days).…”

“…[12] A recent synthesis of data on 378,513 remotely sensed eddies of the World Ocean implied a median radius of 82.33 ± 35.93 km and the median life span of 73.38 ± 66.40 days. [13] The aforementioned observations stating a marked role of mesoscale eddies in spatio-temporal dynamics of geostrophic currents have stimulated our search of the relationship between bioluminescence variability of plankton and the physical characteristics of these eddies.…”

“…[ 12 ] A recent synthesis of data on 378,513 remotely sensed eddies of the World Ocean implied a median radius of 82.33 ± 35.93 km and the median life span of 73.38 ± 66.40 days. [ 13 ]…”

Trajectories modelling of mesoscale anticyclonic eddies in the Mozambique Channel using ANFIS Fuzzy C-Means

“…In the northern hemisphere, the nomenclature is the opposite [3] [4]. Mesoscale oceanic eddies account for 90% of the kinetic energy of the oceans, which dominate the upper ocean flow field [5]. They generate significant impacts on large-scale oceanic circulations, and thus on the mass transport and biogeochemical properties of the ocean [5] and on the global energy cycle [6] [7].…”

“…Mesoscale oceanic eddies account for 90% of the kinetic energy of the oceans, which dominate the upper ocean flow field [5]. They generate significant impacts on large-scale oceanic circulations, and thus on the mass transport and biogeochemical properties of the ocean [5] and on the global energy cycle [6] [7]. Mesoscale coherent oceanic eddies (lifetimes greater than or equal to 30 days) capture nearly 80% of the total kinetic energy in the ocean [8].…”