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14. Thermocline and Halocline


The Briny Deep

1. Introduction
2.  Salt in Seawater?
3. Ions of Salt
4. Source of the Salt?
5. Salinity Variability
6.Salinity & Precipitation
7. Salinity Summary
8. Calculating Salinity
9. Ocean Temperature
10. Solar Radiation
11. Properties
12. Light Penetration
13. Temperature
14. Thermocline
15. Density
16. Layering


Here is a closeup of the previous section, water depth is shown on left, and color codes for temperature and salinity are once again listed on the right.

What is the change in water temperature from the sea surface to a depth of 1000 meters directly below the words "temperature" in the graph?

Used with Permission of
Matthias Tomczak ęCopyright 1997

Since solar radiation from the sun does not penetrate far into the ocean, the water temperature decreases rapidly between 100 and 800 meters, this region of decreasing temperature is called the thermocline.

Used with Permission of Matthias Tomczak ©Copyright 1997ight 1997

The region of rapid change in salinity with depth, if it indeed exists in a particular region,  is called the halocline.  Notice how the halocline is not as well-defined (distinct) as the thermocline.

The increase in water density over this range of water depth, which is caused by a combination of decreasing temperature and/or  increasing salinity, is called the pycnocline.

ęCopyright 1999
March 13, 1999

Send to Don Reed

Department of Geology
San Jose State University

#8 What is the name for the area of decreasing temperature in the ocean?

a) The photic zone.
b) The halocline.
c) The thermocline.
d) The pycnocline.
e) None of the above.