Distributions of ocean properties
Reading:
- Chapter 4 of Talley et al. Use the guide below.
- See also: Stewart Chapter 6…
- http://www-pord.ucsd.edu/~ltalley/sio210/Distributions/index.html
- For T/S diagrams, Sec 6.4.2 of OU.
Things to understand
Setting T-S properties (Sec 4.2)
- What direction do horizontal gradients tend to be the strongest in the ocean?
- Where in the ocean are T-S properties largely determined?
- make sure you are clear what is referred to by the terms “zonal” and “meridional”; also: “equatorial”, “subtropical”, “polar” and “subpolar”, at least their loose meaning.
Surface temperature (4.2.1)
- Describe the range of surface temperatures and where those ranges exist.
- In what direction are the changes the greatest?
The thermocline (4.2.2 and 4.2.3)
- Describe the vertical dist of temperature.
- What is meant by the term “thermocline”?
- What two mechanisms does Talley et al give to explain the existence of the thermocline? Why is a “theory” of the thermocline needed? i.e. what causes there to be one at all? (We’ll discuss more in class).
- What is meant by a “double thermocline” and where do they occur?
Surface mixed layers (4.2.4)
- Why is there a surface mixed layer?
- What two mechanisms mix surface water?
- Describe the seasonal cycle of the mixed layer
- Why is the vertical structure of temperature sometimes different at high lattitudes? In what way is it different?
- What would you expect to happen to the mixed layer in a region where the days are warm and the nights are cold? (this is called the diurnal cycle).
Deep water and potential temperature (4.2.5)
- Why does temperature go up with depth in the Mariana Trench?
- What does potential temperature tell us?
Salinity Distribution
- What sets the ocean salinities?
- Why are salinity profiles often more complicated than temperature profiles?
- What is the general vertical trend of the salinities with depth in the subtropical gyre?
- Where are the saltiest surface salinities and how salty are they?
- Why is salinity higher in the Atlantic than Pacific?
- In terms of the East/West-averaged surface salinities and temperatures, which is most important for the surface density?
- Why is E-P negative just north of the equator?
- Identify the “intermediate” (~1000 m deep) low- and high-salinity masses in figure 4.10b, 4.11b, and 4.12b.
- where does the low-salinity water appear to come from?
- what is the saltiest large water mass in the ocean called? (Based on 4.10b, 4.11b, and 4.12b)
Density Distribution
- Considering the density distribution in Fig 4.11c, what direction do you think $\sigma_4=45.9$ water is moving?
- where does this water come from?
- Any idea what causes the “bowls” in he near surface densities 20 S and N?
Oxygen, Nitrate and Silicate (4.5 and 4.6)
- What do each of these tracers tell us about a water mass?
T/S diagrams and water mass properties.
(OU Sec 6.4.2)
- What is usually plotted in a T/S diagram?
- How can T/S diagrams indicate mixing?