Challenger Deep internal wave turbulence events

TL;DR

This study used long-term high-resolution temperature sensors in Challenger Deep to observe internal wave turbulence, revealing significant turbulent mixing that could support deep-sea life despite extreme pressure conditions.

Contribution

First direct measurement of internal wave turbulence in the Mariana Trench, providing insights into nutrient exchange mechanisms at extreme depths.

Findings

Detected hundreds of meters of slanted convection due to internal waves

Turbulence dissipation rates were hundreds of times above background levels

Turbulence correlated with minute-scale temperature anomalies

Abstract

Marine life has been detected in the ocean's trenches at great depths down to nearly 11 km. Such life is subject to particular environmental conditions of large static pressure exceeding 1000 atmosphere. While current flows are expected to be slow, waters cannot be stagnant with limited exchange of fresh nutrients needed to support life. For sufficient nutrient supply, the physics process of turbulent exchange is required. However, the environmental conditions hamper research in such waters. To study potential turbulent water motions, a string equipped with specially designed high-resolution temperature sensors was moored near the deepest point on Earth in the Challenger Deep, Mariana Trench for nearly three years. A preliminary analysis of a six-day period when the mooring was still demonstrates hundreds of meters slanted convection due to internal waves breaking from above. The associated turbulence dissipation rate with peak values hundred times above the background value is considered sufficient to maintain deep-trench life. Turbulence associates with one-ten thousandth of a degree temperature anomalies of about one hour duration.