OCEANOGRAPHY-2

1.1 COASTAL LANDFORMS

1.2 OCEANIC TEMPERATURE

1.3 OCEANIC SALINITY

1.4 MOVEMENT OF THE OCEAN WATER 

1.1 COASTAL LANDFORMS :

Coastal landforms are physical features that result from the interaction of various natural processes along coastlines. These processes include erosion, deposition, weathering, and the influence of tides, waves, and currents. Coastal landforms can vary widely depending on factors such as the type of rock, climate, sea level changes, and tectonic activity. Here are some common coastal landforms:

1. Beaches:

   - Beaches are accumulations of sand, gravel, or pebbles along the shoreline.

   - They can be formed through the deposition of sediments carried by rivers or waves.

2. Dunes:

   - Sand dunes are mounds or ridges of sand that form as a result of wind-blown sand deposition.

   - They are commonly found along sandy coastlines and are often stabilized by vegetation.

3. Cliffs:

   - Cliffs are steep, vertical, or nearly vertical rock exposures along the coast.

   - They can be formed through processes like erosion, often caused by the action of waves undercutting the base of the cliff.

4. Headlands and Bays:

   - Headlands are elevated coastal areas that extend into the sea.

   - Bays are coastal indentations or recesses in the shoreline.

   - They are often formed by differential erosion, where softer rock erodes more quickly than harder rock.

5. Sea Stacks:

   - Sea stacks are isolated pillars or columns of rock that remain after the erosion of cliffs.

   - They are typically found along wave-cut platforms.

6. Caves, Arches, and Stacks:

   - Caves, arches, and stacks are features formed by coastal erosion.

   - Caves may develop in cliffs through the action of waves, and over time, they can lead to the formation of arches and stacks.

7. Tidal Flats and Marshes:

   - Tidal flats are extensive, flat areas exposed at low tide and covered at high tide.

   - Marshes are wetlands with grassy vegetation that may be influenced by tidal action.

8. Estuaries:

   - Estuaries are semi-enclosed coastal bodies of water where freshwater from rivers and streams meets and mixes with saltwater from the ocean.

   - They are often characterized by diverse ecosystems and serve as important habitats for various species.

9. Barrier Islands:

   - Barrier islands are long, narrow, offshore sandbars parallel to the coastline.

   - They provide protection to the mainland from storm surges and waves.

10. Lagoons:

    - Lagoons are shallow, coastal bodies of water separated from the ocean by barrier islands or sandbars.

    - They can support diverse ecosystems and are often important for marine life.

These coastal landforms are dynamic and continually shaped by natural processes, as well as human activities. They play a crucial role in providing habitats, protecting coastlines, and influencing the local environment.

1.2 OCEANIC TEMPERATURE :

Oceanic temperature refers to the temperature of the Earth's oceans. The temperature of ocean water varies both horizontally and vertically and is influenced by a variety of factors, including location, depth, currents, and season. Here are some key points about oceanic temperature:

1. Surface Temperature:

   - The surface temperature of the ocean varies with latitude, with equatorial regions generally experiencing warmer temperatures than polar regions.

   - It is also influenced by the amount of sunlight received, which is affected by the angle of the sun's rays and factors such as cloud cover.

2. Seasonal Variations:

   - Oceans experience seasonal variations in temperature. In temperate zones, surface temperatures tend to be warmer in summer and cooler in winter.

   - This seasonal variability is more pronounced in shallow coastal areas than in deeper open ocean waters.

3. Thermocline:

   - Below the ocean surface, there is a layer known as the thermocline, where the temperature decreases rapidly with depth.

   - The thermocline acts as a barrier, separating the warmer surface layer from the colder, deeper layers of the ocean.

4. Deep Ocean Temperature:

   - Deeper layers of the ocean, below the thermocline, generally have lower and more stable temperatures. The deep ocean is characterized by cold temperatures, with little variation compared to surface waters.

5. Ocean Currents:

   - Ocean currents play a crucial role in distributing heat around the globe. Warm ocean currents, such as the Gulf Stream, transport warm water from the equator toward the poles, influencing the temperature of coastal regions along their paths.

6. El Niño and La Niña:

   - El Niño and La Niña events are part of the El Niño-Southern Oscillation (ENSO) phenomenon, affecting oceanic and atmospheric conditions in the Pacific Ocean. El Niño events typically lead to warmer-than-average sea surface temperatures, while La Niña events result in cooler-than-average temperatures.

7. Climate Change Impact:

   - Climate change can influence oceanic temperatures. Rising global temperatures can lead to warmer sea surface temperatures, affecting marine ecosystems, weather patterns, and sea levels.

8. Ocean Heat Content:

   - Ocean heat content refers to the total amount of heat stored in the ocean, including changes in temperature and heat absorbed by the ocean. It is a key indicator of Earth's energy balance.

Monitoring oceanic temperature is important for understanding climate patterns, predicting weather events, and assessing the impacts of climate change on marine ecosystems. Scientists use a variety of instruments, including buoys, satellites, and research vessels, to collect data on ocean temperatures at different depths and locations.

1.3 OCEANIC SALINITY :

Oceanic salinity refers to the concentration of dissolved salts in seawater. Salinity is a key property of the Earth's oceans and is measured in parts per thousand (ppt) or practical salinity units (PSU). The average salinity of seawater is approximately 35 ppt or 35 PSU, which means there are 35 grams of dissolved salts per kilogram of seawater. Here are some important aspects of oceanic salinity:

1. Composition of Seawater:

   - The primary components of dissolved salts in seawater are chloride, sodium, sulfate, magnesium, calcium, and potassium. These ions result from the weathering of rocks on land and volcanic activity, with sodium and chloride being the most abundant.

2. Spatial Variability:

   - Salinity varies across the world's oceans, with higher salinity typically found in subtropical regions and lower salinity near the equator and at higher latitudes.

   - Factors influencing spatial variability include precipitation, evaporation, river runoff, and ice melting.

3. Temporal Variability:

   - Salinity levels can also vary over time due to seasonal changes, such as increased precipitation or melting ice in certain seasons.

   - Events like heavy rainfall, which dilutes seawater, can temporarily reduce salinity in coastal areas.

4. Halocline:

   - Similar to the thermocline for temperature, the halocline is a layer in the ocean where salinity changes rapidly with depth.

   - Below the halocline, the deeper layers of the ocean generally have more uniform salinity.

5. Influence of Ice Melting:

   - The melting of ice, particularly in polar regions, can lead to lower salinity in the surrounding seawater. This is because the ice that forms from seawater expels salt, leaving behind a less saline liquid.

6. Ocean Circulation:

   - Ocean currents play a role in distributing salt around the globe. Warm currents, such as the Gulf Stream, carry more salt toward higher latitudes, influencing the salinity of different regions.

7. Estuaries and Coastal Zones:

   - Coastal areas and estuaries often experience lower salinity due to the input of freshwater from rivers and streams, which dilutes the seawater.

8. Climate Change Impact:

   - Climate change can influence oceanic salinity patterns. Changes in precipitation, evaporation, and ice melting can alter salinity levels, impacting ocean circulation and marine ecosystems.

Scientists use various methods to measure oceanic salinity, including conductivity sensors, chemical analyses of water samples, and satellite observations. Understanding oceanic salinity is crucial for studying ocean circulation, climate patterns, and the distribution of marine life. The ocean's salinity levels are relatively stable over long periods, but localized variations and short-term changes occur due to natural processes and human activities.

1.4 MOVEMENT OF THE OCEAN WATER :

The movement of ocean water is a complex and dynamic process influenced by various factors, including winds, temperature, salinity, the Earth's rotation, and the configuration of the ocean floor. There are several key components of oceanic movement:

1. Surface Currents:

   - Surface currents are large-scale, horizontal flows of seawater near the ocean's surface.

   - They are primarily driven by the wind, which imparts energy to the water and sets it in motion.

   - The major surface currents form circular patterns called gyres, which are influenced by the Coriolis effect due to the Earth's rotation.

2. Coriolis Effect:

   - The Coriolis effect is the apparent deflection of moving objects (including air and water) caused by the rotation of the Earth.

   - In the Northern Hemisphere, surface currents are deflected to the right, while in the Southern Hemisphere, they are deflected to the left.

3. Gyres:

   - Gyres are large systems of rotating ocean currents, particularly prominent in the major ocean basins.

   - The five major gyres are the North Atlantic Gyre, South Atlantic Gyre, North Pacific Gyre, South Pacific Gyre, and the Indian Ocean Gyre.

4. Deep Ocean Currents:

   - Deep ocean currents, also known as thermohaline circulation or the ocean conveyor belt, are driven by differences in water density.

   - Cold, dense water sinks at high latitudes, and then it flows along the ocean floor toward lower latitudes. This movement is a slow and deep circulation pattern that can take hundreds or even thousands of years to complete.

5. Upwelling and Downwelling:

   - Upwelling is the rising of cold, nutrient-rich water from the deep ocean to the surface. It often occurs along coastlines.

   - Downwelling is the sinking of surface water, usually in regions where surface water becomes denser, such as at high latitudes.

6. Tides:

   - Tides are the periodic rise and fall of sea levels caused by the gravitational pull of the moon and the sun.

   - Tidal currents are associated with the movement of water as tides rise and fall.

7. Wind-Driven Waves:

   - Wind generates surface waves, which are oscillations of water particles at the ocean's surface.

   - These waves can travel across vast distances and influence coastal processes.

8. Ocean Eddies:

   - Eddies are circular currents that can form within larger ocean currents or gyres. They can have significant impacts on local oceanic and ecological conditions.

9. Estuarine Circulation:

   - In estuaries, the mixing of freshwater from rivers and saltwater from the ocean leads to estuarine circulation patterns, which are influenced by tidal movements and freshwater input.

Understanding oceanic movement is crucial for various reasons, including climate studies, marine biology, navigation, and fisheries management. Ongoing research and advancements in technology continue to improve our understanding of these complex and interconnected processes.