SIO 210 Talley Topic 2: Properties of seawater

Lynne Talley, 1997
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Reading and study questions

Reading (on reserve):

Seawater properties:

Pickard and Emery, chapter 3.1-3.5, 4.25, 6.53, 6.54
Gill, Appendix 3 - just note existence of these very useful tables for equation of state etc.

Distribution of properties:

Pickard and Emery, chapter 4.13, 4.21-4.22, 4.3, 4.4, 4.5, 4.62

My online vertical section atlas: http://sam.ucsd.edu/vertical_sections

Study questions:

Seawater properties

1. What is the difference between accuracy and precision?

2. What properties of seawater determine its density?

3. What is the pressure at the bottom of the ocean relative to sea surface pressure? What unit of pressure is very similar to 1 meter?

4. What is the appropriate temperature scale to use for heat content?

5. What happens to the temperature of a parcel of water (or any fluid or gas) when it is compressed adiabatically? What quantity describes the effect of compression on temperature? How does this quantity differ from the measured temperature? (Is it larger or smaller at depth?)

6. What are the two effects of adiabatic compression on density? What quantity is used to minimize the effect of compression on density?

6. Is cold water more or less compressible than warm water?

7. What is salinity and why do we use a single chemical constituent (which one?) to determine it? What other physical property of seawater is used to determine salinity? What are the problems with both of these methods?

8. Why do we use different reference pressure levels for potential density? (see answer to 6)

9. What is a neutral surface? neutral density?

10. What are the significant differences between freezing pure water and freezing seawater? What happens to the salt in frozen seawater?

11. Fresh water has a density maximum at a temperature above the freezing point, which allows ice to float. Is this also true for sea water? Why does ice formed from sea water float?

12. Why is there a sound speed minimum in the middle of the water column?

Typical profiles and vertical structures

1. How deep is a typical mixed layer if mixed by wind? How deep can it reach if driven by cooling?

2. What are the typical vertical temperature and salinity profiles in the subtropical and subpolar regions of the North Pacific?

3. What is the typical number of layers which people use to describe the ocean in general in mid-latitudes? What are the most general names and typical depth ranges of the layers? (Do not name a specific water mass like "North Atlantic Deep Water".)

4. What is the volumetrically most common water on earth and where is it found?

5. Is the North Atlantic Ocean saltier or fresher on average than the Pacific?

Fortran subroutines for properties of seawater.

You can type them in yourself from the UNESCO tables or get them through netscape or anonymous ftp to the anonymous ftp site on nemo.ucsd.edu:

Netscape instructions

netscape to ftp://nemo.ucsd.edu
click into the subdirectory pub/user_software (in anonym ftp, cd pub/user_software)
retrieve the files: README, ppsw.f and all other files ending in .f

Anonymous ftp instructions

ftp nemo.ucsd.edu
login anonymous
cd pub/user_software
mget *
quit

Further reading

Fofonoff, N.P., 1962. Physical properties of seawater. In The Sea: Ideas and observations on progress in the study of the seas, Vol, 1: Physical Oceanography. M.N. Hill, ed., Wiley, Interscience, new York, pp. 3-30.

Fofonoff, N.P., 1985. Physical properties of seawater. J. Geophys. Res., 90, 3332-3342.

Gill text, pp. 39-45

Mantyla, A., 1987. Standard seawater comparisons updated. J. Phys. Oceanogr., 17, 543-548.

Montgomery, R.B., 1937. A suggested method for representing gradient flow in isentropic surfaces. Bull. Amer. Met. Soc., 18, 210-212.

UNESCO tables, 1983. (Fofonoff and Millard) Includes fortran code (see bottom of study questions to get source code online).

Jackett, D. and T. J. McDougall, 1995. Neutral density. International WOCE Newsletter, 19, 30-33.

Other sources for viewgraphs

Gordon, A.L., 1986. Interocean exchange of thermocline water. J. Geophys. Res., 91, 5037-5046. 339-359.

Hellerman, S. and M. Rosenstein, 1983. J. Phys. Oceanogr., 13, 1093-1104. (wind stress maps)

Hsiung, J., 1985. Estimates of global oceanic meridional heat transport. J. Phys. Oceanogr., 15, 1405-1413. (net heat flux maps)

Levitus, S., 1982. Climatological atlas of the world ocean. NOAA Prof. Paper 13, 173 pp. (climatological data used for average property maps; source of data for gif plots)

Lynn, R.J. and J.L. Reid, 1968. Characteristics and circulation of deep and abyssal waters. Deep-Sea Res., 15, 577-598. (good reference with meridional vertical sections)

Reid, J.L., 1969. Sea-surface temperature, salinity, and density of the Pacific Ocean in summer and in winter. Deep-Sea Res., 16 (suppl), 214-224. (surface property maps)

Reid, J.L. and R. J. Lynn, 1971. On the influence of the Norwegian-Greenland and Weddell seas upon the bottom waters of the Indian and Pacific oceans. Deep-Sea Res., 18, 1063-1088.

Schmitt, R., P. Bogden, C. Dorman, 1989. Evaporation minus precipitation and density fluxes for the North Atlantic. J. Phys. Oceanogr., 19, 1208-1221.

Stommel, H. P. Niiler, and D. Anati, 1978. Dynamic topography and recirculation of the North Atlantic. J. Mar. Res., 36, 450-468.

Talley, L.D., 19484. Meridional heat transport in the Pacific Ocean. J. Phys. Oceanogr., 14, 231-241.

Wijffels, S. E., R. W. Schmitt, H. L. Bryden and A. Stigebrandt, 1992. Transport of freshwater by the oceans. J. Phys. Oceanogr., 22, 155-162.

Worthington, L.V., 1981. The water masses of the world ocean: some results of a fine-scale census. In Evolution of Physical Oceanography, MIT Press, 42-69.

Wyrtki, K., 1975. Fluctuations of the dynamic topography in the Pacific Ocean. J. Phys. Oceanogr., 5, 450-459.