North Pacific Current

The North Pacific Current.

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 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, running northward off the coast of Japan, and the Oyashio Current, 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, it splits into the southward flowing California Current and the northward flowing Alaska Current.

Flows & 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 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 receives about about 60% of the flow of the NPC while the California Current 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 westward 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

External links

Quick Bulletin of Ocean Conditions around Japan

Ocean currents and gyres

Currents

Arctic Ocean	East Greenland North Icelandic Norwegian Transpolar Drift Stream
Atlantic Ocean	Angola Antilles Azores Baffin Island Benguela Brazil Canary Cape Horn Caribbean East Greenland East Iceland Falkland Florida Guinea Gulf Stream Irminger Labrador Lomonosov Loop North Atlantic North Brazil North Equatorial Norwegian Portugal Slope Jet South Atlantic South Equatorial West Greenland West Spitsbergen
Indian Ocean	Agulhas Agulhas Return East Madagascar Equatorial Counter Indian Monsoon Indonesian Throughflow Leeuwin Madagascar Mozambique North Madagascar Somali South Australian South Equatorial West Australian
Pacific Ocean	Alaska Aleutian California Cromwell Davidson East Australian East Korea Warm Equatorial Counter Humboldt Indonesian Throughflow Kamchatka Kuroshio Mindanao North Equatorial North Korea Cold North Pacific Oyashio South Equatorial Tasman Front
Southern Ocean	Antarctic Circumpolar Tasman Outflow

Gyres

Major gyres	Indian Ocean Gyre North Atlantic Gyre South Atlantic Gyre North Pacific Gyre South Pacific Gyre
Other gyres	Beaufort Gyre Ross Gyre Weddell Gyre

^[1] ^[2]

↑ 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

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