Accelerated internal tides in a warming climate.

Area of Science:

• Oceanography
• Climate Science
• Tidal Dynamics

Background:

• Internal tides are crucial for ocean mixing and marine ecosystems.
• Previous studies on internal tides were limited in scope and duration.
• Long-term global data on internal tides are scarce, hindering understanding of climate change impacts.

Purpose of the Study:

• To investigate the long-term global behavior of internal tides.
• To assess the impact of global warming on internal tide speeds.
• To identify the primary drivers of changes in internal tide dynamics.

Main Methods:

• Utilized data from the Coupled Model Intercomparison Project Phase 6 (CMIP6).
• Employed the High-Resolution Empirical Tidal (HRET) model for analysis.
• Analyzed trends in globally averaged internal tide speeds over historical and future periods.

Main Results:

• A significant accelerating trend in global internal tide speeds was identified.
• Historical rates of increase were 0.4 cm/s per decade, projected to reach 2.0 cm/s per decade.
• Intensified upper-ocean stratification is the primary driver, with background currents playing a secondary role.

Conclusions:

• Internal tides are projected to propagate faster in a warming climate.
• Accelerated internal tides could influence ocean energy cascades.
• Changes in internal tides may have substantial effects on marine biological productivity.