Sea surface salinity
Variation in precipitation & evaporation generate changes in sea water salinity
- Near equator, little evaporation & high rainfall; salinity of surface water is usually low (<35 PPT)
- In subtropics, much evaporation & little rainfall; salinity of surface water is high (>35 PPT)
- In mid-latitudes, little evaporation & high rainfall; salinity of surface water is low (may be seasonal)
- At poles, freezing of sea water freezes at surface; salinity of surface water is high