1. Winter (Sea Ice Formation):
- During the winter months in polar regions, temperatures drop significantly, causing seawater to freeze and form sea ice.
- As seawater freezes, salt is excluded from the ice crystals and remains in the remaining liquid water. This concentrated liquid water beneath the sea ice has higher salinity than the surrounding seawater.
- The formation of sea ice leads to an overall increase in the salinity of the water within the polar regions.
2. Spring and Summer (Sea Ice Melting):
- As spring and summer approach, temperatures rise, and sea ice begins to melt. This process releases the highly saline water trapped beneath the ice back into the ocean.
- The melting ice dilutes the surrounding seawater, reducing its salinity.
- As a result, the overall salinity of the water decreases during this period.
3. Fall (Mixing and Circulation):
- During the fall season, there is a transition period where the remaining sea ice melts, and the water column begins to mix.
- This mixing process distributes the less saline surface water to deeper layers, while denser, more saline water from deeper regions rises to the surface.
- The mixing of water masses leads to a more uniform salinity distribution throughout the water column.
The continuous cycle of sea ice formation and melting throughout the year causes seasonal variations in salinity, leading to higher salinity levels during winter and lower salinity levels during spring and summer in polar regions.
