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220 METEOROLOG!' FOR MARIjYERS

the east coasts of Scotland and England to thc Thamcs estuary, where it curvcs eastwards. It is thcre joined by a branch of thc North Atlantic Current which passes up the English Channcl and through the Dover Strait. The combincd current flows along the Belgian and Netherlands coasts and west coast of Jutland. It continues counter-clockwise round the Skagerrak and then scts northwards along thc west coast of Norway.

Only a portion of thc current on thc west sidc of thc North Sca reaches as far south as thc Thames estuary, for water fans out eastwards from this current all along its length.

Bay of Biscay

Off the mouth of thc Bay of Biscay the current trends south-castwards and latcr flows southwards along the west coast of the Ibcrian pcninsula. A branch enters thc Bay and rccurvcs westwards along thc north coast of Spain to rcjoin this current near Cabo Finisterrc.

Mediterranean

Part of the water from thc Portugal Current enters thc Strait of Gibraltar and flows along the north coast of Africa. Bcyond Cap Bon it continues in a generał south-easlerly and later casterly dircction towards Port Said. The water turns northwards at the eastem end of the Mediterranean and thc counter-clockwise etreulation is completed by a morę variable return current along thc northern coasts. In following thc coast, this forms counter-clockwise loops in scas such as the Aegean and thc Adriatic.

Black Sea

The generał circulation is counter-clockwise. Thcrc is an almost constant surface flow of water from the Black Sea to the. Aegean through thc Bosporus, the Sca of Marmara and thc Dardanclles. There is a sub-surface return current below this, from the Aegean to the Black Sea.

Gulf of St Lawrence

Water enters the Gulf on the northern side of Cabot Strait and flows northwards along the west coast of Ncwfoundland. It then turns south-westwards, along the Qucbec coast and is west-going southwards of Anticosti. The Gaspe Current sets south-eastwards from thc Gaspe Peninsula. Water emerges from thc Strait by thc Cape Breton Current on the Southern side of Cabot Strait; this is sometimes callcd the Cabot Current.

Gulf of Mexico

Part of thc water passing through Yucatan Channcl turns westwards and follows the gulf coast in a eloekwise direction. Anothcr branch scts northwards across the middle of thc gulf to the region of the Mississippi delta, where it turns eastwards and joins the Coastal current. The combincd current passes into thc Florida Current between Cuba and Florida.

SOUTH ATLANTIC OCEAN

Main Circulation

The main surface circulation of this ocean is counter-clockwise. The South

CURRENT CIRCULATIONS OF THE OCE ANS

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Equatorial Current, flowing westwards across the ocean, cxtends a cross the cquator to about latitudc 4°n. South of about latitudc 6°s thc constancy and strength of thc wcsterly flow gradually dccrcascs southwards. The main con-ccntration of the South Equatorial Current is between about latitudcs 6°s and 4°n.

The eastern side of the circulation is formed by thc rclatively cool Benguela Current flowing north-westerly along thc south-western coasts of Africa. From about latitude 30°$, water from the Benguela Current fans out west-north-wcstcrly and wcsterly on its seaward side.

While most of thc South Equatorial Current flows along the north coast of Brazil and across thc cquator to join the North Equatorial Current, the wcsterly flow on its southcrly flank is dirccted towards the Brazilian coast, southwards of Cabo de Sao Roque. A smali part of this turns northwards along that coast and passes round Cabo de Sao Roquc to join the South Equatorial Current; the bulk of it flows southwards along the Brazilian coast. This warm current, known as the Brazil Current, forms the west side of thc South Atlantic circulation.

The Southern Ocean Current flows all round thc globe in the southermost parts of the South Atlantic, South Indian and South Pacific Oceans, and forms thc complction, on the Southern side, of thc counter-clockwise circulation in these oceans. The Southern Ocean Current is rcstricted in width by passing through Drakę Passagc, between Cabo de Hornos and Graham Land. Eastwards of this passagc it bccomcs very wide, its northern part fanning out north-eastwards past the Southern and eastern coasts of thc Falkland Islands, to reach to about thc 40th parallcl in the central longitudcs of thc South Atlantic.

Furthcr north, the Southern part of thc main circulation is added to by water from thc seaward side of the Brazil Current curving south-eastwards and eastwards between latitudcs 28°s and 40^cs. In mid ocean part of the resultant castcrly flow runs north of and parallel to the colder water of the Southern Ocean Current; thc rcmainder merges with the northerly part of thc Southern Ocean Current. East of about longitude I5°w and south of the 30th parallel, the east-going water turns north-east and north to converge with the westerly flow which fans out from thc seaward side of the Benguela Current.

Nearer the South African coast, between longitudcs io°e and I5°e, a branch of thc Southern Ocean Current turns northwards directly into thc Benguela Current. The water of the Benguela Current is, howcvcr, mainly dcrived by thc upwclling of water ofT the south-west coast of Africa. A branch of the Agulhas Current of the South Indian Ocean, which rounds thc south coast of Africa, also enters thc Benguela Current.

Ihe Falkland Current docs not form part of the main circulation; it branches northwards from the Southern Ocean Current near Statcn Island and passes west of thc balkland Islands. Part of it continues to the Rio de la Plata estuary; thc remainder branches eastwards in about latitudes 40°s to 42°s and rcjoins the northern part of the Southern Ocean Current. During May to Octobcr a northerly cxtcnsion of the Falkland Current continues north of Rio dc la Plata. From May to July this may extend as far as Cabo Frio.

NORTH INDIAN OCEAN

Monsoonal Effects

The currents in the greater part of thc North Indian Ocean, including the