Equatorial Undercurrent

Japanese: 赤道潜流 - せきどうせんりゅう（英語表記）Equatorial Undercurrent

An ocean current that flows eastward along the equator, below the westward South Equatorial Current. It was discovered in the Pacific Ocean in 1951. It is also called the Cromwell Current after its discoverer, T. Cromwell. The maximum flow speed is about 100 m deep just below the equator, and it reaches a speed of about 2 to 3 knots. Its flow rate is about 40×10 ⁶ m ³ /s, and it is a strong current comparable to the Kuroshio Current and the Gulf Stream. It exists between 2° north and 2° south latitudes, and is almost symmetrical about the equator. Its typical thickness is about 200 m, and it has a thin lens-like cross section. It is due to the unique property of the equator that the Coriolis force is not effective, and its existence has been confirmed not only in the Pacific Ocean, but also in the Atlantic Ocean and the Indian Ocean. However, in the Indian Ocean, where the wind direction changes seasonally, it exists at least during the latter half of the northeast monsoon season, but does not exist or is weak and unstable during the southwest monsoon season.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

西向きの南赤道海流の下を，赤道に沿って東向きに流れる海流。 1951年に太平洋で発見された。発見者 T.クロムウェルにちなみ，クロムウェル海流ともいう。流速が最大のところは，赤道直下の約 100m深であり，大きさは約2～3ノットに達する。流量は約 40×10⁶m³/s で，黒潮やメキシコ湾流にも匹敵する強流である。北緯2°と南緯2°の間に存在し，赤道に関してほぼ対称をなす。代表的な厚さは約 200mで，薄いレンズ状の断面をしている。コリオリの力がきかないという赤道特有の性質に起因しており，太平洋に限らず，大西洋でもインド洋でもその存在が確かめられている。ただし，風向が季節変化をするインド洋では，少くとも北東季節風期後半には存在するものの，南西季節風期には存在しないか存在しても弱く，しかも不安定である。

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