Extremely long Kelvin-Helmholtz billow trains in the Romanche Fracture Zone

• Published in: Geophysical Research Letters
• Main Authors: van Haren, Hans, Gostiaux, Louis, Morozov, Eugene, Tarakanov, Roman
• Other Authors: Royal Netherlands Institute for Sea Research (NIOZ), Laboratoire de Mecanique des Fluides et d'Acoustique (LMFA), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), P.P. Shirshov Institute of Oceanology (SIO), Russian Academy of Sciences Moscow (RAS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SPI]Engineering Sciences [physics]; [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]; Antarctic; Mid-Atlantic Ridge; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-01166123; https://hal.archives-ouvertes.fr/hal-01166123/document; https://hal.archives-ouvertes.fr/hal-01166123/file/VANHAREN__GRL_2014.pdf; https://doi.org/10.1002/2014GL062421

International audience In the Atlantic Ocean, the densest water mass Antarctic Bottom Water " AABW " can only cross the Mid-Atlantic Ridge from its southwestern to northeastern basins in limited, because deep, conduits. At the southwestern entrance of one of these, the equatorial Romanche Fracture Zone, AABW crosses a sill at 4550 m depth in a 7 km narrow channel before plunging into the deep. At the sill-slope, the rapidly flowing AABW causes shear-induced turbulent mixing with the overlying water masses. We present an excerpt of 1 Hz sampled, half-yearlong moored observations from 99 high-resolution temperature sensors that demonstrate and quantify the turbulence details. On top of quasi-steady shear flow, an internal tide modulates the mixing. Together, they constitute a means for an extremely long train of >250 consecutive Kelvin-Helmholtz billows in a day that vary between 5 and 100 m in vertical scale.