Lecture 19: Southern Ocean, formation of the ACC Flashcards
(14 cards)
What is the physical definition of the Southern Ocean?
Everything south of the Antarctic Convergence or within and south of the Antarctic Circumpolar Current (ACC).
What is the political definition of the Southern Ocean?
The region between 60°S and the coast of Antarctica.
What is the Antarctic Circumpolar Current (ACC)?
A massive, wind-driven geostrophic current encircling Antarctica, connecting all major ocean basins.
What drives the Antarctic Circumpolar Current?
Strong circumpolar westerly winds.
What are the two major gyres south of the ACC?
The Ross Sea Gyre and the Weddell Gyre.
How does Ekman transport influence vertical water movement in the Southern Ocean?
It causes divergence that drives deep-water upwelling along sloping isopycnal surfaces.
What is upwelling and where does it occur in the Southern Ocean?
Upwelling is the rise of deep waters to the surface, driven by wind-induced divergence, especially under the westerlies.
What are isopycnals?
Surfaces of equal potential density.
What is baroclinity?
The condition where isopycnals and isobars are not aligned, leading to vertical mixing and instability.
What causes diapycnal mixing?
Instability from baroclinic conditions, which moves water across isopycnal layers.
What is the role of the Southern Ocean in the global climate system?
It closes the global ocean circulation, absorbs a large fraction of anthropogenic CO₂ and excess heat, and supports unique ecosystems.
What are typical wind patterns around Antarctica?
Westerlies over the ACC and coastal easterlies near the continent.
What is the relationship between wind, Ekman transport, and upwelling in the Southern ocean?
Westerly wind causes northward Ekman transport, leading to divergence and upwelling of deep water.
What does static stability depend on in the ocean?
The vertical gradient of density; positive gradient = stable, negative = unstable.
