Friday, August 31, 2018

Mysterious Zones of Antarctica - 3

Seawater transport @ Southern Ocean
Today we look deeper into the Southern Ocean current which transports more water than all the rivers of the Earth combined.

The graphic to the left depicts a rough layout of the Antarctic Circumpolar Current (ACC), the Subantarctic Front (SAF), and the Subtropical Convergence or Subtropical Front (STF).

The blue line above the coast of Antarctica, which zigs and zags a bit, is the "Southern Ocean current which transports ["up to 150 times"] more water than all the rivers of the Earth combined"  and is described in full detail in the article I have linked to in previous posts of this series (The Antarctic CP Current, ACC, ACC System).
"Bottom of the world"  view

West Indian Ocean [Area A]
East Indian Ocean [Area B]
Ross Sea [Area C]
Amundsen Sea [Area D]
The two circles in Area C and Area F are "gyres with clockwise surface circulation in the Weddell Sea [Area F] and in the Ross Sea [Area C]" (ibid).
Bellingshausen Sea [Area E]
Weddell Sea [Area F]

The graphs below match the areas ('A' - F') with their names and show their area's seawater Conservative Temperature (CT) at depths greater than 600 meters down to 1300 meters.

The shallower depths with their seawater temperatures were featured in previous posts (0 to 125m, greater than 125m to 600m).

One thing to remember is that the boundaries and temperatures mentioned in some of the older published papers may have changed since then: "This area of divergence has been considered to be the ACC's southern boundary (Klinck and Nowlin, 1986) but new analysis puts the southern boundary of the ACC further poleward"

This is to be expected since "The global oceans together absorb over 90 percent of the excess heat in the climate system and roughly three-quarters of that heat uptake occurs in the Southern Ocean" (Antarctica 2.0 - 3).

Thus, as more and more global warming is absorbed by the world oceans (~93% now), and as ~75% of that 93% ends up in the Southern Ocean, we can look for additional changes.

Those less-cold waters being pushed around Antarctica at a rate larger than all of the planet's rivers combined is going to continue to disintegrate the tidewater glaciers there.

And that disintegration will be done at an accelerating rate rather than at a constant rate.

Anyway, as the graphs show, the patterns of seawater temperature are different from one another at these depths as they were in the previous depths shown in the previous posts.

The source of these different patterns seems clear to me ... it is the most powerful current on the planet, which circles Antarctica impacting temperatures at great depths.

In the next post we will take a look at the deepest depths there which we have measurements for.

After all, we do better when we consider our planet with actual measurements (The World According To Measurements, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17).

The following video features a well-know expert on the Cryosphere's largest member.

The next post in this series is here, the previous post in this series is here.

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