Ekman currents in the Antarctic circumpolar current ...

• Main Author: Roach, C
• Format: Thesis
• Language: unknown
• Published: University Of Tasmania 2023
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://dx.doi.org/10.25959/23241905.v1; https://figshare.utas.edu.au/articles/thesis/Ekman_currents_in_the_Antarctic_circumpolar_current/23241905/1

The action of wind on the ocean surface results in the formation of Ekman spirals, as proposed by V.W. Ekman in 1905. The spirals display exponential decay of current speed and anticyclonic rotation with increasing depth. Observations of Ekman spirals are extremely rare, and there are few studies that test Ekman theory against observations. Here we present a unique array of velocity profiles from EM-APEX profiling floats, which we use to examine the nature of Ekman spirals in the Southern Ocean and test how well they are described by theory. Classical Ekman theory assumes the momentum mixing within the upper ocean is set by a constant eddy viscosity. However, previous observational studies have found Ekman spirals to be compressed, with different viscosities estimated from current speed and rotation. This behaviour has been linked to surface trapping of Ekman currents (Price et al. 1987) or could arise due to a failure to consider depth varying geostrophic currents (Polton et al. 2013). We use 1400 profiles ...