Introduction to the ocean
An ocean is the largest water reservoir of earth. Ocean consists of about 71 % water of the hydrosphere. The ocean plays the most important role in the hydrologic cycle and weather patterns. More than 40 % of the world’s population lives within 100 km of the coastline. the present sea level has mostly remained constant for the last 5,000 years.
Geography of ocean
The Pacific Ocean is the largest oceans. It extends from the USA to Australia and Asia. The Atlantic Ocean extends between Europe and North America and between South America and Africa. The Indian Ocean extends to the south of Asia between Africa and Australia. Most of the water resides in the Pacific, Atlantic, and Indian oceans.
The Antarctica continent is completely surrounded by the Southern Ocean. however, some marine geologist considers the Southern Ocean as part of the Pacific, Atlantic, and Indian oceans. The Arctic ocean is located at the north pole.
Generally, the average temperature of the ocean surface is around 17 degrees. Temperature varies with latitude. the water is warmer at the latitude where solar radiation is maximum. The ocean temperature decreases with depth.
The water of the ocean is saline, so it can’t be used for drinking. By weight, an average of 3.5 percent of ocean water contains dissolved salts. the sodium and chlorine are the main elements that contribute to the ocean salinity. There are many reasons ocean water salinity. the river consists of dissolved salts that later go into the ocean. volcanic eruptions also cause of such mineral into oceans. Salinity continuously increases with depth.
Evaporation also increases the salinity of the water, because evaporation increases the salt concentration in water. The ocean salinity is high in the area where evaporation occurs more than rain. Salinity is lower near the equator because rainfall is greater at these latitudes.
Depth, density, and volume of the ocean
The average depth of the ocean is about 3.6 km. the Mariana Trench is the deepest point in the ocean. the Mariana Trench point located near the island of Guam in the western Pacific about 11 km deep. The Pacific Ocean is the deepest ocean and its average depth is about 14,000 feet.
The present volume of seawater is about 1.35 billion cubic kilometers and interestingly more than half of this volume resides in the Pacific Ocean. The density of the ocean is mainly due to dissolved salt. The density of ocean surface water is about 1027 kg/m3.
the ocean current is the directed movement of the seawater. these movements are caused by wind or difference in water density. These movements are different at the surface and at the deep in the ocean.
surface ocean currents are driven by Unequal surface solar heating that causes water to expand and move. Winds is another factor that drives the movement of surface water. the deep ocean water movements are caused by variation in density due to temperature and salinity differences. this is called thermohaline circulation.
The Coriolis force and Ekman transport are the two forces that influence the direction of ocean currents. The Coriolis force doesn’t cause the ocean current, it only deflects the current path. The Coriolis force is caused by earth rotation and it’s faster at equator compare to poles. Due to the Coriolis force, all moving bodies are deflected to the right in the northern hemisphere and to the left in the southern hemisphere. The Ekman transport shows the net direction of water movement at about 90° to the wind direction.
Ocean waves, tides, and tsunami
Ocean waves are just like other waves, it’s formed due to turbulence in the water. the wind that blows across the sea surface produces the ocean waves. the tsunami is the ocean wave caused by the sudden movement of the seafloor. this sudden turbulence is due to earthquake, coastal landslide or large volcanic eruption.
Tides are the periodic rise and fall in oceanic water. Tides are the result of gravitational attraction between the earthy, moon, and sun along with the rotation of the earth.
The river deposits a large amount of sediment in the ocean. Ocean sediment is the result of weathering, erosion, and transportation. ocean sediments can be sand, clay, dust, carbonate and silicate particles, volcanogenic particles, and glacially derived particles. the sediments accumulate in the seafloor and make the layer of sediment.