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Extremely long Kelvin‐Helmholtz billow trains in the Romanche Fracture Zone
Author(s) -
Haren Hans,
Gostiaux Louis,
Morozov Eugene,
Tarakanov Roman
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062421
Subject(s) - sill , geology , antarctic bottom water , ridge , oceanography , fracture zone , circumpolar deep water , convective mixing , seamount , mid atlantic ridge , shear (geology) , water mass , geomorphology , deep water , north atlantic deep water , petrology , convection , paleontology , meteorology , geography
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.