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Investigating the Relationship between Sea Surface Chlorophyll and Major Features of the South China Sea with Satellite Information
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Detecting changes at the leading edge of an interface between oceanic water layers
Qunshu Tang1,2, Vincent C H Tong3, Richard W Hobbs4
1CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Guangzhou, China. tqsh@scsio.ac.cn.
Nature Communications
|October 16, 2019
Summary
Ocean boundary layers evolve through mixing and stratification. Seismic imaging reveals a critical transition from turbulent diffusion to double-diffusion in stratified layers over three days.
Area of Science:
- Oceanography
- Geophysics
- Fluid Dynamics
Background:
- Ocean phenomena involve interactions between water masses of differing temperatures and salinities.
- Finescale structure at boundaries is crucial, being either destroyed by mixing or formed by stratification.
Purpose of the Study:
- To characterize finescale structure at marginal interaction zones of ocean boundaries.
- To observe temporal changes at the leading edge of an interface between sub-thermocline layers.
- To provide empirical constraints on stratified layer evolution using time-lapse seismic reflection imaging.
Main Methods:
- High-resolution seismic reflection imaging was employed.
- Time-lapse images of a seismic reflector between two water boundaries were studied.
- Analysis focused on the leading edge of the reflector and its associated temperature contrast.
Main Results:
- Temporal changes at the leading edge of a seismic reflector were observed over approximately three days.
- The leading edge increased in length, correlating with an increase in temperature gradient.
- A critical mixing state was identified, transitioning from turbulent diffusion to double-diffusion.
Conclusions:
- Stratified layers evolve dynamically at ocean boundaries.
- Seismic reflection imaging provides insights into mixing processes.
- The study reveals a transition in dominant mixing mechanisms in the ocean.
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