The Kinematic Similarity of Two Western Boundary Currents Revealed by Sustained High‐Resolution Observations

Abstract

Western boundary currents (WBCs) modulate the global climate and dominate regional ocean dynamics. Despite their importance, few direct comparisons of the kinematic structure of WBCs exist, due to a lack of equivalent sustained observational data sets. Here we compare multiyear, high‐resolution observations (1 km, hourly) of surface currents in two WBCs (Florida Current and East Australian Current) upstream of their separation point. Current variability is dominated by meandering, and the WBCs exhibit contrasting time‐mean velocities in a Eulerian coordinate frame. By transforming to a jet‐following coordinate frame, we show that the time‐mean surface velocity structure of the WBC jets is remarkably similar, considering their distinct local wind, bathymetry, and meandering signals. Both WBCs show steep submesoscale kinetic energy wavenumber spectra with weak seasonal variability, in contrast to recent findings in other ocean regions. Our results suggest that it is the mesoscale flow field that controls mixing and ocean dynamics in these regions.

Interoperability of Direction-Finding and Beam-Forming High-Frequency Radar Systems: An Example from the Australian High-Frequency Ocean Radar Network

“…The primary product of the HFR network is ocean current maps; waves and winds can also be obtained where the phased-arrays systems are installed. Radar data, freely available from the IMOS portal (https://portal.aodn.org.au/), are used for scientific research, operational modeling, coastal monitoring, fisheries, and other applications [36][37][38][39][40][41][42].…”

Global Perspectives on Observing Ocean Boundary Current Systems

“…High-frequency (HF) radars (Paduan and Washburn, 2013) have been used effectively to monitor surface current variability of boundary currents (e.g., Kim et al, 2011;Archer et al, 2018). They directly map the total surface current within O(100) km of the coast at high resolution in time (∼1 h) and space (∼1 km) during long-term deployments (∼10 years).…”

“…They directly map the total surface current within O(100) km of the coast at high resolution in time (∼1 h) and space (∼1 km) during long-term deployments (∼10 years). HF radar observations have proven useful for investigating both the mean surface velocity structure of boundary currents and associated submesoscale features that develop as boundary currents meander and shed eddies (Archer et al, 2018;Soh and Kim, 2018). Combining HF radar velocity estimates with satellitebased measurements of SST and ocean color (e.g., Figure 4) can provide a multidisciplinary view of surface circulation features at O(1)-km scales (e.g., .…”

Improving Data Quality for the Australian High Frequency Ocean Radar Network through Real-Time and Delayed-Mode Quality-Control Procedures

“…Each HFR node is configured primarily to sample ocean currents with a maximum range of over 200 km; however, at selected locations where the phased-arrays systems are installed, waves and winds can also be obtained. Radar data, freely available from the IMOS portal (https://portal.aodn.org.au/), are used for scientific research, operational modeling, coastal monitoring, fisheries, and other applications [1][2][3][4][5][6][7]. This paper focuses on the quality-control (QC) procedures that have been implemented for the phased array systems in Australia and are applied operationally on both the near real-time (NRT) and delayed-mode (DM) products.…”