Drake Passage

Assembled from 12 blocks · 2 evidence · 5 related

1. Story
2. The gap between the tip of South America and the Antarctic Peninsula, and the narrowest constriction on the Antarctic Circumpolar Current's circuit. Because the whole current must pass through it, the passage has been the natural place to measure the ACC since the 1970s; the cDrake array of moored current meters and pressure-recording inverted echo sounders occupied it from 2007 to 2011 and produced the 173.3 Sv mean transport figure. The opening of this gateway, together with the deepening of the Tasman gateway, is what allowed a circumpolar current to exist at all, though when that happened is genuinely disputed.
3. Knowledge
4. Drake Passage
5. Connections
6. Antarctic Circumpolar Current (ACC)
7. Antarctic Circumpolar Current (ACC)
8. A circumpolar current becomes possible
9. Drake Passage is measured and the ACC turns out to be larger
10. Evidence
11. Continuous Drake Passage observations from 2007 to 2011 give a mean ACC transport of 173.3 Sv — barotropic 45.6 ± 8.9 Sv plus baroclinic 127.7 Sv relative to zero at the seafloor — about 30 per cent above the canonical benchmark value. Figures taken from search summaries of the abstract; the article is on a blocked publisher domain.
12. The timing of ACC onset is contested: this paper places the modern ACC in the late Miocene, while other studies place onset near the Eocene–Oligocene transition (~34 Ma), at ~31 Ma from foraminiferal and neodymium evidence, at ~30 Ma from Tasmanian gateway–westerly alignment, and at ~24 Ma from flow-speed and water-mass homogeneity records. The disagreement is stated, not resolved; none of the papers was fetched.