Question

why differences are there in the salinity of oceans?​

Answer 1

Answer:

Evaporation of ocean water and formation of sea ice both increase the salinity of the ocean. However these "salinity raising" factors are continually counterbalanced by processes that decrease salinity such as the continuous input of fresh water from rivers, precipitation of rain and snow, and melting of ice.

Answer 2

Explanation:

Surface salinity is greatly influenced in coastal regions by the fresh water flow from rivers, and in polar regions by the processes of freezing and thawing of ice. Wind, also influences salinity of an area by transferring water to other areas. The ocean currents contribute to the salinity variations.