Southern Ocean: Climate, Islands, Depth, Location, Currents


The Southern Ocean is the newest ocean recognized by the United States Board on Geographic Names. The International Hydrographic Organization (IHO) created the Ocean as the fifth ocean ranking as the fourth largest ocean in the world representing fifteen percent of the earth’s water. The ocean is believed to form after the separation of South America and Antarctica due to the formation of the Antarctic Circumpolar Current.

The total area of the Southern Ocean is 35,000,000 square kilometers however believed to be expanding around the world. It is subdivided into seas, straits, bays, channels, and gulfs. It is said that the Southern Ocean can influence the global climate as it connects to the three major oceans: Indian, Atlantic and Pacific Oceans. It stores the huge amount of heat, carbon dioxide, and nutrients and helps to drive the currents of the Ocean all around the world. The paper will further discuss about its climate, islands, depth, location, and currents.

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The Southern Ocean is the coldest and windiest ocean on Earth. It is covered by the 1-2 meters of ice-sheet spreading up to 4 kilometers with sea temperatures varying -2 °C to 10 °C and with the average temperatures of 2-4°C. The climatic conditions of Southern Ocean depend on the seasons. The summer season of Southern Ocean runs from October to February while winter season falls from March to September. During winter, sea temperature could drop down to -40°C and freezes the ocean that ranges below 65 degrees south latitude below 55 degrees south latitude in the Southern Atlantic Ocean. The seawater that can be cooled at -2°C shrinks and spreads over the ocean.

It is said that the Southern Ocean influences the global ocean circulation. Because of its connection with the Pacific, Atlantic, and Indian ocean, the Southern Ocean is considered to be the gateway where the bottom, intermediate, and deep waters interconnect with other sea’s surface as well as influencing the atmosphere.

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In the Southern Ocean, the waters always flow eastward. During a cyclonic storm, the waters travel to the east around the continent. Storms happen when the temperature contrast between the ice and the open ocean. The area of the ocean that ranges the latitude 40 south traveling to the Antarctic circle is said to have the strongest average winds found anywhere on Earth. It is believed that most prominent attribute of the Southern Ocean is the strong seasonal cycle of the ice and its surface temperature, especially on the waters that surrounding the Antarctic continent. This cycle is due to the wind stress that and ocean currents that vary, playing an interactive role in the exchange of heat between the ocean and the atmosphere.


There are several islands that bound the Southern Ocean. This includes the continent of Antarctic to the south, and the continents of South America, Africa, Australia and Broughton Island and New Zealand, in the north. The Southern Ocean was outlined by land-based limits that were from Cape Horn in South America eastwards to Cape Agulhas in Africa, then further eastwards to the Southern coast on Mainland Australia to Cape Leeuwin which is in Western Australia.

The limit follows eastwards then to the west coast of Tasmania South woods, then to the Southeast Cape leading to Broughton Island and New Zealand, and then back to Cape Horn. However, in the International Hydrographic Organization (IHO) in the second edition of the Limits of Oceans and Seas, the Southern Ocean is moved Southward from Africa to Western Australia and extended to latitude 55 degrees south between Auckland Island of New Zealand and in South America.

Southern Islands are believed to be the most isolated landmasses in the world with few having a human settlement and therefore remain to be not intervened in the world. Among the islands of the Southern Ocean, the Heard Island is known as the most isolated and remote island on earth. It is located on the undersea Kerguelen Plateau in the Southern Ocean and believed to be of a volcanic origin.

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It has a distance of 4000 km from south-west of Australia, 3750 km from Africa, and 7500 km from India, 1500 km from Antarctica. It has an area of 367 km2 in the region at 53°S latitude, south of the Antarctic Convergence and it is covered with 70% glaciers. The island was discovered in 1853 and because of its remoteness, the island is not exposed to frequent visitation and no plants and animals from human have introduced.

The value of the Southern Islands has been recognized for the purpose of scientific research since in the mid-19th century. Therefore, many authors who addressed about the conservation of the Southern Ocean also emphasize the significance of the Southern islands being the nesting grounds of seabirds, endemic species and become an example of mid-to-high latitude terrestrial biomes in the Southern latitudes. However, some believe that the area is less important due to the ice and glaciers that cover mostly of the land, affecting the diversity and abundance of the plants and animal species. The debate about the conservation of Southern Islands still remains as of today.


The Southern Ocean has an average depth of 13,100 feet to 16,400 feet. There are oceanic basins farther north that are as much as 14,800 feet deep. The deepest in the region is located at the Southern end of South Sandwich Trench that has a depth of 23,737 feet. Another feature that includes the oceanic plates that are located in the oceanic basin is the New Zealand Plateau, which rises in the Southeast of New Zealand. It has an average depth of fewer than 6,650 feet or 2,000 meters below sea level and believed to be the most extensive plateau in the Southern basin.

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The Southern Ocean is located at 68.4380° S, 160.2340° W on the Southern portions of the Atlantic Ocean, Indian Ocean, and the Pacific Ocean. It surrounds the whole region of Antarctica that extends North to 60 degrees South latitude.


In the Southern Ocean, the flow of currents is complex. The main current of the ocean is the Antarctic Circumpolar Currents (ACC) that flows from west to east and all the way around the region of Antarctica. The Antarctic Circumpolar Current travels up to 150 billion liters per second which are equivalent to 150 times the water contained in the rivers all over the world. ACC consists the series of individual currents that is separated by frontal zones.

There are about 140 million tons per second that passed through the gap between South America and Antarctica. When the region of South America and Antarctica split apart, Drake Passage was opened. The Drake Passage is known as the narrowest stretch of water in the Southern Ocean that approximately spanned for 500 miles between Southern tip of South America and West Antarctic Peninsula. Among the parts of the Southern Ocean, Drake Passage is the most observed since it provides the link between Pacific and Atlantic Oceans and narrows the Antarctic Circumpolar Current.

The swirls in the Antarctic Circumpolar Current are large enough to mix the water depths seabed down to 3500 meters. It often forms when the Antarctic Circumpolar Current meets the large seabed. The way how the waters of Southern Ocean run through the other ocean is through routes. Each route flows at mid-ocean depths where it has the north-flowing parts in the deep and shallow ocean. The flows are managed by winds, water density, and tide activity.

References: victoria , biologicalsciences
Photo by: Pexels

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