Spring Bloom Colors the Pacific Near Hokkaido

The , also known as the Okhotsk Current or Kurile Current, is a cold

subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of hemiboreal regions and covering much of Alaska, Canada, Iceland, the north of Fennoscandia, Northwestern Russia, Siberia, and the Cair ...

ocean current An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, sh ...

that flows south and circulates counterclockwise in the western North

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. The waters of the Oyashio Current originate in the

Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It spans an area of approximately and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, ...

and flow southward via the

Bering Sea The Bering Sea ( , ; rus, Бе́рингово мо́ре, r=Béringovo móre, p=ˈbʲerʲɪnɡəvə ˈmorʲe) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasse ...

, passing through the Bering Strait and transporting cold water from the Arctic Sea into the Pacific Ocean and the Sea of Okhotsk. It collides with the

Kuroshio Current The , also known as the Black Current or is a north-flowing, warm ocean current on the west side of the North Pacific Ocean basin. It was named for the deep blue appearance of its waters. Similar to the Gulf Stream in the North Atlantic, the Ku ...

off the eastern shore of

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

to form the

North Pacific Current The North Pacific Current (sometimes referred to as the North Pacific Drift) is an ocean current that flows west-to-east between 30th parallel north, 30 and 50th parallel north, 50 degrees north in the Pacific Ocean. The current forms the souther ...

(or Drift). The nutrient-rich Oyashio is named for its metaphorical role as the that provides for and nurtures marine organisms.

Climate impact

The current has an important impact on the climate of the

Russian Far East The Russian Far East ( rus, Дальний Восток России, p=ˈdalʲnʲɪj vɐˈstok rɐˈsʲiɪ) is a region in North Asia. It is the easternmost part of Russia and the Asia, Asian continent, and is coextensive with the Far Easte ...

, mainly in

Kamchatka The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...

and Chukotka, where the northern limit of tree growth is moved south up to ten degrees compared with the latitude it can reach in inland

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

. The waters of the Oyashio Current form probably the richest

fishery Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...

in the world owing to the extremely high nutrient content of the cold water and the very high

tides Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

(up to ) in some areas – which further enhances the availability of nutrients. However, the Oyashio Current also causes

Vladivostok Vladivostok ( ; , ) is the largest city and the administrative center of Primorsky Krai and the capital of the Far Eastern Federal District of Russia. It is located around the Zolotoy Rog, Golden Horn Bay on the Sea of Japan, covering an area o ...

to be the most equatorward

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...

to seasonally freeze and require icebreaking ships to remain open in winter. Nonetheless, this has relatively little effect on the fish yield through the Sea of Okhotsk, because the large tides mean freezing does not occur so easily.

History

During

glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

s, when lower

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

exposed the

Bering land bridge Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72° north latitude in the Chukchi Sea; and on the south by the tip of the ...

, the current could not flow in the regions the Oyashio affects today. The level of cooling with the onset of glacial conditions (after an

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...

) was much less than in other areas of the Earth at similar latitudes. This allowed Tōhoku and

Hokkaidō is the second-largest island of Japan and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by railway via the Seikan Tunnel. The ...

– the only areas of

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

with enough snowfall to potentially form glaciers – to remain unglaciated except at high elevations during periods when Europe and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

were largely glaciated. This lack of glaciation explains why, despite its present climate being much colder than most of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, East Asia has retained 96 percent of

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Oceanic gyres * Physical oceanography

References

*Reddy, MPM (2001): ''Descriptive physical oceanography''. Taylor and Francis, , pp 367–8.

External links

Regional Definition page for the Oyashio Current
UNEP Global International Waters Assessment (GIWA), accessed 26 July 2018 {{Ocean Currents of the Pacific Ocean Bering Strait Temperate Northern Pacific