Main Menu
8.
Salinity Summary
The Briny Deep
Menu
1. Objectives
2. Salt in Seawater?
3. Ions of Salt
4. Source of the Salt?
5. Salinity Variability
6. Salinity & Precipitation
7. Salinity & Precipit II
8. Salinity Summary
9. Calculating Salinity
10. Ocean Temperature
11. Solar Radiation
12. Properties
13. Light Penetration
14. Temperature
15. Thermocline
16. Density
17. Layering
Here is a map showing the salinity of the surface waters of the ocean, down to a water depth of 50 meters, in parts of dissolved salt per 1000 (o/oo) parts of sea water.
Image produced by WOCE Ocean Modeling at the Naval Postgraduate School
- Compare your observations in this map with your answers to the question in section 6
Where do you find the high salinity waters in the surface of the ocean?
Where do you find low salinity sea water in the surface of the ocean?
Low salinity water (light blue region at 10-150 north) lies in the polar and subpolar regions and near the equator. The equatorial region of low salinity ocean water lies below an atmospheric region called the "intertropical convergence zone".
Intertropical Convergence Zone
The intertropical convergence zone moves about the equator as the intense heat in the equatorial area produces a rising mass of moisture-laden air, thereby creating a region of low atmospheric pressure.
The equatorial low pressure system pulls air and moisture from adjacent regions towards the equator. Consequently, air masses converge in this region from north and south of the equator, bringing moisture acquired by evaporation in the subtropical regions.
The warm, humid air along the equator rises (because of its low density) and cools, allowing water vapor to condense, which results in rainfall, causing precipitation to exceed evaporation in equatorial regions.
Draw a picture of the intertropical convergence zone in your handou
- Moving poleward, another region of low sea surface salinity lies around 60o north and south of the equator, where once again precipitation is greater than evaporation, due to rising masses of air that produce heavy rainfall.
Image produced by WOCE Ocean Modeling at the Naval Postgraduate School
In contrast to these low salinty areas, where do you find regions of high salinity sea water?
Regions of high salinity sea water are centered around 30o north and 30o south of the equator (orange regions on map above) because of excess evaporation in these regions.
As we will see in a future expedition, these areas of high evaporation and ocean salinity are located below high pressure systems in the atmosphere marked by cold, sinking air, which pushes rain clouds away from these regions by the wind.
You Should
Now Be Able to Develop a Hypothesis
about Each of the Following Questions
How would the salinity be affected by the freezing of ice from seawater, so-called sea ice?
Photo From the Alfred Wegener Institute
How would the ocean's salinity change as a result of rainfall, runoff, or the melting of ice?
©Copyright 1999
March 13, 1999
Send to Don Reed
Department of Geology
San Jose State University
