The horizontal distribution of ocean water properties refers to the variations in temperature, salinity, density, and other characteristics across different oceanic regions. These variations are influenced by factors like latitude, ocean currents, wind patterns, and proximity to landmasses.
1. Temperature Distribution
Factors Influencing Horizontal Temperature Distribution:
- Latitude: The amount of solar radiation received varies with latitude, affecting ocean temperature.
- Ocean Currents: Currents transport warm or cold water across different regions, influencing temperature distribution.
- Seasonal Changes: Seasonal variations cause temperature changes, particularly in temperate and polar regions.
- Proximity to Land: Coastal regions can have different temperatures compared to open ocean due to land-sea interactions.
Example:
- The Gulf Stream and North Atlantic Drift: The Gulf Stream carries warm water from the Gulf of Mexico northeastward across the Atlantic, moderating the climate of western Europe. As a result, places like the British Isles and Norway have milder winters than other regions at similar latitudes.
2. Salinity Distribution
Factors Influencing Horizontal Salinity Distribution:
- Evaporation and Precipitation: High evaporation rates increase salinity, while high precipitation rates decrease it.
- River Discharge: Freshwater input from rivers reduces salinity near river mouths.
- Ice Formation and Melting: Ice formation increases salinity by leaving salt behind, while melting ice decreases it.
- Ocean Currents: Currents can transport saline water, affecting regional salinity levels.
Example:
- The Mediterranean Sea: This semi-enclosed sea has higher salinity (around 38 ppt) compared to the open ocean (about 35 ppt) due to high evaporation rates and limited freshwater input. Water exiting the Mediterranean through the Strait of Gibraltar is saltier than the surrounding Atlantic water.
3. Density Distribution
Factors Influencing Horizontal Density Distribution:
- Temperature: Warmer water is less dense than colder water.
- Salinity: Higher salinity increases water density.
- Pressure: Though pressure increases with depth, horizontal variations in pressure at the surface can also affect density.
Example:
- Equatorial vs. Polar Regions: In equatorial regions, warm, low-density water dominates the surface layers. In contrast, polar regions have cold, high-density water. These density differences drive large-scale ocean circulation patterns like the thermohaline circulation.
4. Nutrient Distribution
Factors Influencing Horizontal Nutrient Distribution:
- Upwelling: Coastal upwelling brings nutrient-rich deep water to the surface, supporting high biological productivity.
- River Input: Rivers carry nutrients from land to coastal regions, enhancing productivity.
- Ocean Currents: Currents can transport nutrients, influencing productivity in different regions.
Example:
- Peruvian Upwelling: Along the coast of Peru, strong upwelling brings cold, nutrient-rich water to the surface, supporting one of the world’s richest fisheries. This nutrient influx leads to high primary productivity and abundant marine life.
5. Oxygen Distribution
Factors Influencing Horizontal Oxygen Distribution:
- Photosynthesis: In regions with high phytoplankton activity, photosynthesis increases oxygen levels.
- Temperature: Colder water can hold more dissolved oxygen than warmer water.
- Ocean Currents: Currents can transport oxygenated water to different regions.
Example:
- The North Pacific Subtropical Gyre: This area, known for its low productivity and high temperature, has lower dissolved oxygen levels compared to regions with upwelling, like the eastern Pacific.
6. Pollution and Human Impact
Factors Influencing Horizontal Pollution Distribution:
- Industrial Discharge: Coastal areas near industrial regions can have higher concentrations of pollutants.
- Marine Traffic: Shipping lanes can have higher levels of oil and chemical pollutants.
- Runoff: Agricultural runoff can lead to nutrient pollution and eutrophication in coastal regions.
Example:
- The Great Pacific Garbage Patch: This large area of the Pacific Ocean is characterized by high concentrations of plastic debris, primarily due to ocean currents concentrating waste in this region.
Conclusion
The horizontal distribution of ocean water properties is a complex interplay of natural and anthropogenic factors. Understanding these distributions is crucial for marine science, as they affect climate, marine ecosystems, and human activities. The Gulf Stream’s impact on European climate, the Mediterranean’s high salinity, Peruvian upwelling’s nutrient richness, and the Great Pacific Garbage Patch’s pollution concentration are all prime examples of how these factors manifest in the real world.
