Main factors affecting seawater salinity

The factors affecting seawater salinity include precipitation, evaporation, runoff, solubility and so on.

1. In the open sea or ocean, the main factors affecting seawater salinity are precipitation and evaporation. In coastal areas, salinity is mainly affected by river runoff;

2. The salinity of seawater changes with the latitude of sea area, which is mainly influenced by latitude, rivers, ocean isobath and ocean current.

3. From low latitude to high latitude, the salinity of seawater mainly depends on the difference of evaporation and precipitation. Evaporation concentrates seawater, while precipitation dilutes seawater. In the sea area where rivers are injected, the salinity of seawater is generally low.

(1) Near the equator, rainfall is greater than evaporation, which reduces the salinity of seawater;

(2) The trade winds around 20 degrees south latitude and 20 degrees north latitude are the trade winds of the earth. The weather is dry, the rainfall is small, the evaporation is much higher than the rainfall, and the salinity of seawater naturally increases;

(3) Located in high latitudes near the South Pole and the North Pole, the temperature is low, the evaporation is small, the rainfall is increased, and the salinity is relatively small.

Seawater salinity refers to the ratio of the total dissolved solids in seawater to the weight of seawater, usually expressed in grams per kilogram of seawater. People use salinity to express the mass fraction of salt substances in seawater. The average salinity of the world oceans is 35%.

The surface seawater of the world's oceans is affected by evaporation, precipitation, freezing, melting ice and land runoff, and the salinity distribution is uneven: the salinity near the poles, equatorial regions and sea areas affected by land runoff is relatively small; In the sea area of 20 degrees north and south latitude, the salinity of seawater is relatively high; The salinity of deep seawater has little change, which is mainly controlled by physical processes such as circulation and turbulent mixing.