Temperature Distribution of Ocean Water
The temperature of the ocean is critical for marine organisms such as plants (phytoplanktons) and animals (zooplankton). The temperature of seawater influences the climate of coastal lands, as well as the plants and animals that live there.
It is important to investigate both the surface and subsurface temperatures of seawater. Surface temperature is measured using standard thermometers, while subsurface temperature is measured using reversing thermometers and thermographs. The Sun is the oceans’ primary source of heat energy. Because seawater has a higher specific heat than land, its heating and cooling processes are much slower. Oceans have a large heat storage capacity.
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Ocean Water Temperature Sources
Two major sources of ocean temperature are as follows:
- The Sun heats the water, and the temperature is diffused or reached depth due to convection.
- Bottom water receives heat from volcanic activity along oceanic ridges.
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Temperature Distribution of Ocean Water Influencing Factors
The Temperature Distribution of Ocean Water is influenced by several factors, including:
Latitude: As the amount of insolation decreases from the equator to the poles, the temperature of the surface water decreases as well.
Uneven Distribution of Land and Water: The northern hemisphere’s oceans receive more heat due to their contact with a larger area of land than their southern hemisphere counterparts. As a result, the temperature of surface water is higher in the northern hemisphere than in the southern hemisphere.
Prevailing Wind: Winds blowing from the land towards the oceans/sea (offshore winds) drive warm surface water away from the coast, causing cold bottom water from below to upwell.
This causes temperature variations along the way. On the contrary, onshore winds (which blow from the ocean to land) accumulate warm water near the coast, raising the temperature.
Ocean Currents: Warm currents raise the temperature of the affected areas, while cool currents lower the temperature. The Gulf Stream (warm current) raises the temperature of eastern North America and Europe’s west coast. The Labrador cool current reduces the temperature near North America’s northeast coast. Siberia’s eastern coast temperature drops due to the Kurile cool current.
Minor factors such as submarine ridges, and local weather conditions such as storms, hurricanes, fog, cloudiness, evaporation, and condensation all have an effect on the surface temperature of the ocean water. In the low latitudes, enclosed seas have higher temperatures than open seas, while in the high latitudes, enclosed seas have lower temperatures than open seas.
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Horizontal Temperature Distribution in Oceans
The diurnal and annual temperature ranges of oceans are much smaller than those of land. The average temperature of the ocean’s surface water decreases gradually from the equator to the poles. The rate of temperature decrease with increasing latitude is typically 0.5°C per latitude. The average temperature at 22° latitude is about 22° C, 14° C at 40° latitude, and 0° C near the poles.
The highest temperature is recorded slightly north of the equator, rather than at the equator. Temperatures in the northern hemisphere oceans are higher than in the southern hemisphere oceans. This is because the northern and southern hemispheres have unequal distributions of land and water. The average annual temperature of the northern hemisphere oceans is around 19°C, while the average annual temperature of the southern hemisphere oceans is around 16°C.
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Vertical Temperature Distribution in Oceans
The maximum temperature of the oceans is always at their surface because it receives direct insolation and heat is transmitted to lower levels of the oceans via convection. From the surface to the bottom, the oceans are divided into three layers. The upper layer/first layer – This is the warm oceanic water’s top layer. It is approximately 500m thick, with temperatures ranging between 20°C and 25°C.
This layer exists all year in the tropics, but it only appears in the mid-latitudes during the summer. The transitional zone/second layer/thermocline layer is located beneath the upper layer. This layer is distinct in that the temperature decreases rapidly as depth increases.
This layer has a thickness of 500-1000 m. In the deep ocean, approximately 90% of the total volume of water is below the thermocline. The temperature in this zone is close to zero degrees Celsius.
The lower/third layer of the ocean is extremely cold and extends all the way to the deep ocean floor. Temperature changes with depth are very small in the Arctic and Antarctic oceans because surface water temperatures are close to 0°C.
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Temperature Distribution of Ocean Water UPSC
The water warms up more slowly than air but can hold more heat because water requires four times as much energy to raise its temperature by one degree Celsius as the same mass of the air, so the ocean plays an important role in absorbing energy from the Sun and preventing the Earth from becoming too hot.
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