Deep ocean hydrographic variability estimated from distributed geodetic sensor arrays off northern Chile

Area of Science:

• Oceanography
• Deep-sea research
• Physical oceanography

Background:

• Deep ocean spatio-temporal variability and mesoscale dynamics are poorly understood.
• Limited data exists on the deep ocean's hydrographic characteristics.

Purpose of the Study:

• To investigate deep ocean hydrographic variability and mesoscale dynamics.
• To analyze spatio-temporal patterns of temperature, salinity, and density.
• To understand the influence of the deep-sea trench on ocean currents.

Main Methods:

• Utilized 2.5 years of high-resolution temperature, pressure, and sound speed data.
• Employed three distributed sensor arrays in the deep ocean offshore northern Chile.
• Estimated salinity and density to analyze the full hydrographic variability spectrum.

Main Results:

• Observed interannual warming (0.002–0.003 °C yr⁻¹) on the continental slope.
• Traced periodic hydrographic anomalies, potentially coastal-trapped waves, to the lower continental slope.
• Identified a change in anomaly characteristics across the deep-sea trench, suggesting limited abyssal current extension.

Conclusions:

• The deep-sea trench acts as a barrier, restricting the abyssal eastern boundary current system.
• Evidence suggests a southward flow along the mid to lower continental slope, concentrated near the trench.
• Periodic hydrographic anomalies provide insights into deep ocean dynamics and connectivity.