The North Pacific Current (sometimes referred to as the North Pacific Drift) is a slow warm water current that flows west-to-east between 30 and 50 degrees north in the

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

. The current forms the southern part of the North Pacific Subpolar Gyre and the northern part of the North Pacific Subtropical Gyre. The North Pacific Current is formed by the collision of the

Kuroshio Current The , also known as the Black or or the 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 ...

, running northward off the coast of Japan, and the

Oyashio Current , also known as Oya Siwo, Okhotsk or the Kurile current, is a cold subarctic ocean current that flows south and circulates counterclockwise in the western North Pacific Ocean. The waters of the Oyashio Current originate in the Arctic Ocean an ...

, which is a cold subarctic current that flows south and circulates counterclockwise along the western North Pacific Ocean. In the eastern North Pacific off southern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...

, it splits into the southward flowing cold water

California Current The California Current is a cold water Pacific Ocean current that moves southward along the western coast of North America, beginning off southern British Columbia and ending off southern Baja California Sur. It is considered an Eastern bound ...

and the northward flowing

Alaska Current The Alaska Current is a southwestern shallow warm-water current alongside the west coast of the North American continent beginning at about 48-50°N. The Alaska Current produces large clockwise eddies at two sites: west of the Haida Gwaii ("Hai ...

Flows and temperature

Originating from the eastward directed flow occurring east of the island of Honshu, Japan, the North Pacific Current extends over 40° of longitude. According to the Great Soviet Encyclopedia, the NPC may be considered to be a part or an extension of the Kuroshio current. The current covers a large area and transports warmer water from the subtropics to the sub-polar latitudes. Average sea surface temperature along the NPC can range in the winter from 45-61°F (7.2-16.1°C) and in the summer months 64°F-74°F (17.8-23.3°C). As it flows from west to east, the latitudinal extent of the NPC increases such that it spans some 20 degrees of latitude east of the dateline. This is associated with a decrease in the speed of current; eastward directed speeds at the surface are typically less than 0.05 m/s (5 cm/s) in the central Pacific. As the NPC approaches the west coast of North America, it divides into two broad currents: the northward flowing Alaska Current and the southward flowing California Current. This splitting of flow is referred to as the

bifurcation Bifurcation or bifurcated may refer to: Science and technology * Bifurcation theory, the study of sudden changes in dynamical systems ** Bifurcation, of an incompressible flow, modeled by squeeze mapping the fluid flow * River bifurcation, the ...

of the NPC. The Gulf of Alaska and the California Current receive different volumes and flows of warm water from the North Pacific Current. The

Gulf of Alaska The Gulf of Alaska (Tlingit: ''Yéil T'ooch’'') is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the east ...

receives about 60% of the flow of the NPC while the

receives the remaining 40%. These values may fluctuate, resulting in changes in the volume and the speed of the NPC water entering into the Alaska and California Currents.

Gyre contribution

The NPC forms the northward portion of the North Pacific Subtropical Gyre. As the eastward extension of the Kuroshio, the flow of the NPC can lead to the transport of material from the western Pacific to the coast of North America. For example, some of the marine debris from the Japanese earthquake and tsunami of 2011 was transported by the NPC across the Pacific, leading to deposition of tsunami debris along the shores of Alaska, British Columbia, Washington and Oregon.

References

* The Great Soviet Encyclopedia, 3rd Edition (1970-1979) * H. Freeland, What Proportion of the North Pacific Current Finds its Way into the Gulf of Alaska? Atmosphere-Ocean, November 2010 pp.321-330

External links

Quick Bulletin of Ocean Conditions around Japan

{{Ocean Currents of the Pacific Ocean