Hydraulically Controlled Bottom Flow in the Orkney Passage

Supercritical hydraulically controlled overflow of Antarctic Bottom Water from the Weddell Sea has been observed in Orkney Passage during field measurements February 2022. The is main pathway for densest layer flow to Scotia Sea. bottom current overflows sill across passage and flows down crest at 3600 m deeper than 4000 m. descending accelerates because difference height its foot. An estimate Froude number this was greater unity. Near foot slope kinetic energy becomes insufficient continue moving regime. slows down, strong mixing warming water occurs due exchange with surrounding waters. This hydrodynamic phenomenon called supercritical flow. However, continues further eventually fills abyssal depths Atlantic.