Oceanic salinity refers to the concentration of dissolved salts in seawater, typically expressed in parts per thousand (ppt). The normal range of salinity is 33-37 ppt. It is a critical parameter in oceanography, influencing various aspects of the Earth''s climate system and marine ecosystems.

Factors Affecting Ocean Salinity:

• Evaporation and precipitation: The salinity of water in the surface layer of oceans depends mainly on evaporation and precipitation. 
• For instance, regions with high rates of evaporation, such as subtropical areas, experience higher salinity levels because water evaporates, leaving behind concentrated salt. Conversely, regions with high precipitation, like the equator or coastal zones, have lower salinity due to dilution by freshwater input.
• Fresh water flow: Surface salinity is greatly influenced in coastal regions by the freshwater flow from rivers, and in polar regions by the processes of freezing and thawing of ice.
• For instance, the areas of oceans/seas bordering the continental areas are less saline than interior areas due to influx of fresh water from rivers.
• Sea Ice Formation and Melting: During sea ice formation, the expelled salt increases the salinity of surrounding seawater, leading to dense, cold, and saline water sinking and contributing to global ocean circulation. Conversely, when sea ice melts, it releases freshwater, reducing the salinity of surrounding waters.
• Ocean Circulation and Mixing: Ocean currents and mixing processes play a significant role in redistributing seawater with different salinity levels. 
• For example, the Atlantic Ocean''s Gulf Stream transports warm and saline water from the tropics to higher latitudes, impacting regional salinity patterns.
• Ocean depth: The salinity of the water body increases with increase in depth of oceans. Due to rainfall and influx of fresh waters from rivers, the salinity of surface water is less.

Multi-dimensional Effects of Ocean Salinity:

• Ocean Density and Circulation: Salinity, together with temperature, determines seawater density. Variations in salinity influence ocean circulation patterns, as denser water sinks and initiates deep ocean currents. This circulation helps regulate Earth''s climate by redistributing heat globally.
• Marine Ecosystems: Salinity directly affects marine life, particularly organisms adapted to specific salinity ranges. Drastic changes in salinity can disrupt marine ecosystems, affecting the distribution and abundance of marine species.
  • For example, Coral reef are very sensitive to the changes in salinity of the ocean.
• Climate Regulation: Ocean salinity is intimately linked to the global water cycle and climate regulation. Changes in salinity impact the ocean''s capacity to absorb and store heat, which, in turn, influences atmospheric circulation and weather patterns.
• Sea Level Changes: Variations in oceanic salinity affect sea level through their impact on water density. 
  • For instance, changes in sea level can have significant implications for coastal communities and ecosystems.
• Ocean Acidification: Salinity plays a role in regulating the ocean''s carbonate system. As CO2 levels rise due to human activities, ocean acidification occurs, affecting marine organisms with calcium carbonate shells and skeletons.
• Water Resource Management: In coastal regions, variations in salinity affect the availability and quality of freshwater resources, impacting agriculture, human settlements, and ecosystems.

Understanding and monitoring variations in oceanic salinity are essential for predicting and adapting to the impacts of climate change, improving marine resource management, and protecting vulnerable ecosystems. Remote sensing technologies and oceanographic studies provide valuable insights into these variations, aiding in the sustainable management of our oceans and their vital role in the Earth''s climate system.