We cannot learn about the weather we experience without considering the ocean and its effect on our weather – and the weather’s effect on it. We must consider the ocean because nearly 71% of the Earth’s surface is covered by it and more than 97% of all our water is contained in it.
Understanding the ocean and its relationship to weather is critical as more than half of the world’s population lives within 60 miles (100 km) of the ocean.
The ocean’s ability to absorb, store, and release heat into the atmosphere is huge and often directly affects us. In fact, just the top 10 feet of the ocean surface contains more heat than our entire atmosphere. Major climate events, such as El Niño, result from ocean temperature changes. These temperature changes have impacts on weather events such as hurricanes, typhoons, floods and droughts which, in turn, affect the prices and availability of fruits, vegetables, and grains.
The sizes of the major oceans
Ocean
Surface Area (miles2)
Surface Area (kilometers2)
Of all oceans
Pacific
64,000,000
166,000,000
45.0%
Atlantic
31,600,000
82,000,000
22.2%
Indian
28,400,000
73,600,000
20.0%
Southern
13,523,000
35,000,000
9.5%
Arctic
4,700,000
12,173,000
3.3%
With all of this water, it is essential that we consider the ocean.
Layers of the Ocean
Typical seawater temperature profile (red line) with increasing depth.
Sea surface temperatures for a single year: 2014 (900 kb). Download Image
Sea surface temperatures over three years: 2012-14 (2.6 mb) Download Image
Sea surface temperatures over six years: 2009-14 (5.4 mb) Download Image
Epipelagic Zone
This surface layer is also called the sunlight zone and extends from the surface to 200 meters (660 feet). It is in this zone tha
t most of the visible light exists. With that sunlight comes heat from sun, which is responsible for wide variations in temperature across this zone, both with the seasons and latitudes – sea surface temperatures range from as high as 97°F (36°C) in the Persian Gulf to 28°F (-2°C) near the North Pole.
Wind keeps this layer mixed and thus allows the sun’s heat to be distributed vertically. The base of this mixing layer is the beginning of the transition layer called the thermocline.
Mesopelagic Zone
Below the epipelagic zone is the mesopelagic zone, extending from 200 meters (660 feet) to 1,000 meters (3,300 feet). The mesopelagic zone is sometimes referred to as the twilight zone or the midwater zone, as sunlight this deep is very faint. Temperature changes are the greatest in this zone because it contains the thermocline, a region where water temperature decreases rapidly with increasing depth, forming a transition layer between the mixed layer at the surface and deeper water. The depth and strength of the thermocline varies from season to season and year to year. It is strongest in the tropics and decrease to non-existent in the polar winter season.
Because of the lack of light, bioluminescence begins to appear on organisms in this zone . The eyes on the fishes are also larger and generally upward directed, most likely to see silhouettes of other animals (for food) against the dim light.
Bathypelagic Zone
The depths from 1,000-4,000 meters (3,300 – 13,100 feet) comprise the bathypelagic zone. Due to its constant darkness, this zone is also called the midnight zone. The only light at this depth and lower comes from the bioluminescence of the animals themselves.
The temperature in the bathypelagic zone, unlike that of the mesopelagic zone, is constant. The temperature never fluctuates far from a chilling 39°F (4°C). The pressure in the bathypelagic zone is extreme and at depths of 4,000 meters (13,100 feet), reaches over 5850 pounds per square inch! Yet, sperm whales can dive down to this level in search of food.
Abyssopelagic Zone
The Abyssopelagic Zone (or abyssal zone) extends from 4,000 meters (13,100 feet) to 6,000 meters (19,700 feet). It is the pitch-black bottom layer of the ocean. The water temperature is constantly near freezing, and only a few creatures can be found at these crushing depths.
The name (abyss) comes from a Greek word meaning “no bottom” because they thought the ocean was bottomless. Three-quarters of the area of the deep-ocean floor lies in this zone.
Hadalpelagic Zone
The deepest zone of the ocean, the hadalpelagic zone extends from 6,000 meters (19,700 feet) to the very bottom, 10,994 meters (36,070 feet) in the Mariana Trench off the coast of Japan.
The temperature is constant, at just above freezing. The weight of all the water over head in the Mariana Trench is over 8 tons per square inch.
Even at the very bottom, life exists. In 2005, tiny single-celled organisms called foraminifera, a type of plankton, were discovered in the Challenger Deep trench southwest of Guam in the Pacific Ocean. The deepest a fish have ever been found, Abyssobrotula galatheae, was in the Puerto Rico Trench at 8,372 meters (27,460 feet).
Ocean Circulations
In January 1992, a container ship near the International Date Line, headed to Tacoma, Washington, from Hong Kong, lost 12 containers during severe storm conditions. One of these containers held a shipment of 29,000 bathtub toys. Ten months later, the first of these plastic toys began to wash up onto the coast of Alaska. Driven by the wind and ocean currents, these toys continue to wash ashore during the next several years, and some even drifted into the Atlantic Ocean.
The ultimate reason for the world’s surface ocean currents is the sun. The heating of the earth by the sun has produced semi-permanent pressure centers near the surface. When wind blows over the ocean around these pressure centers, surface waves are generated by transferring some of the wind’s energy, in the form of momentum, from the air to the water. This constant push on the surface of the ocean is the force that forms the surface currents.
Around the world, there are some similarities in the currents. For example, along the west coasts of the continents, the currents flow toward the equator in both hemispheres.
These are called cold currents as they bring cool water from the polar regions into the tropical regions. The cold current off the west coast of the United States is called the California Current.
Likewise, the opposite is true as well. Along the east coasts of the continents, the currents flow from the equator toward the poles. There are called warm current as they bring the warm tropical water north. The Gulf Stream, off the southeast United States coast, is one of the strongest currents known anywhere in the world, with water speeds up to 3 mph (5 kph).
Ocean currents will have a huge impact on long-term weather any location will experience. For example, due to the Gulf Stream, the overall temperature of Norway and the British Isle is about 18°F (10°C) higher in the winter than other regions located at the same latitude.
While ocean currents are shallow-level circulations, there is global circulation which extends to the depths of the sea called the Great Ocean Conveyor. Also called the thermohaline circulation, it is driven by differences in the density of the sea water which is controlled by temperature (thermal) and salinity (haline).
In the northern Atlantic Ocean, as surface water flows north, it cools considerably. When the water cools to a point where sea ice forms, the salts are extracted (meaning sea ice is fresh-water ice). The extracted salts make the water beneath the sea ice more dense, causing it to sink to the ocean floor.
This motion drives a slowly southward flowing deep-ocean current. The route of the current is through the Atlantic Basin around South Africa and into the Indian Ocean and on past Australia into the Pacific Ocean Basin.
If the water is sinking in the North Atlantic Ocean, then it must rise somewhere else. This upwelling is relatively widespread. However, water samples taken around the world indicate that most of the upwelling takes place in the North Pacific Ocean.
It is estimated that once the water sinks in the North Atlantic Ocean, it takes 1,000-1,200 years before that deep, salty bottom water rises back to the upper levels of the ocean again.
The Great Ocean Conveyor Belt – The dark blue line represents the deep, cold, and saltier water current. The red line indices shallower and warmer current. Download Image
