Lecture 21: Southern Ocean processes & water properties

Question 1

What are key processes in polar oceans that affect water properties?

Answer 1

Polar ocean processes include surface heat and freshwater fluxes, sea ice formation and melt, and mixing due to cooling and storm activity.

Question 2

What happens to the mixed layer in summer versus winter?

Answer 2

In summer, it’s shallower and warmer; in winter, it’s deeper and colder due to convection and mixing.

Question 3

What is buoyancy flux and how is it calculated?

Answer 3

Formula:
Fbo = g(aT * Qnet - aS *Fnet) / cp0

It represents the effect of heat and salinity fluxes on seawater buoyancy.

Question 4

What is brine rejection and when does it occur?

Answer 4

Brine rejection occurs when sea ice forms, expelling salt into the surrounding water, increasing salinity and density, leading to sinking.

Question 5

How does sea ice affect freshwater distribution?

Answer 5

Sea ice acts as a moving freshwater reservoir, storing fresh water at the surface and transporting it northward.

Question 6

Name three major Southern Ocean water masses.

Answer 6

Antarctic Surface Water (AASW)

Subantarctic Mode Water (SAMW)

Antarctic Bottom Water (AABW)

Question 7

What is Subantarctic Mode Water (SAMW) and where does it form?

Answer 7

SAMW forms through winter cooling and mixing in the Subantarctic Front (SAF) zone.

Question 8

What role does the Southern Ocean play in global circulation?

Answer 8

It closes the global overturning circulation by ventilating the deep ocean and influencing global heat and carbon budgets.

Question 9

What is the effect of negative buoyancy flux in winter?

Answer 9

Dense, cold water sinks, mixing the water column and contributing to deep water formation.

Question 10

What causes seasonal changes in ocean stratification?

Answer 10

Variations in temperature and salinity between seasons change the density gradient, affecting stratification.