Translation 3820
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ARCHIVES. FISHERIES AND MARINE SERVICE Translation Series No. 3820 • IV The ocean environment of the world by Keiji Nasu Original title: IV Sekai ni okeru kaiyo kankyo From: Oceanic Environments and the Living Resources of the World. p. 30-80, 1975 Translated by the Translation Bureau( JWC ) Multilingual Services Division Department of the Secretary of State of Canada Department of the Environment Fisheries and Marine Service Pacific Biological Station Nanaimo, B.C. 1976 95 pages typescript DEPARTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT TRANSLATION BUREAU BUREAU DES TRADUCTIONS MULTILINGUAL SERVICES DIVISION DES SERVICES DIVISION MULTILINGUES F n-)er-3rilPo TRANSLATED FROM - TRADUCTION DE INTO - EN Japanese Enmlish AUTHOR - AUTEUR Keiji NASU TITLE IN ENGLISH - TITRE ANGLAIS IV The ocean environment of the world. TITLE IN FOREIGN LANGUAGE (TRANSLITERATE FOREIGN CHARACTERS) TITRE EN LANGUE ÉTRANGÉRE (TRANSCRIRE EN CARACTÈRES ROMAINS) IV Sekai ni okeru kaiyo kankyo. REFERENCE IN FOREIGN LANGUAGE (NAME OF BOOK OR PUBLICATION) IN FULL. TRANSLITERATE FOREIGN CHARACTERS. RÉFÉRENCE EN LANGUE ÉTRANGÉRE (NOM DU LIVRE OU PUBLICATION), AU COMPLET, TRANSCRIRE EN CARACTÈRES ROMAINS. Sekai no kaiyo kankyo to shigen seibutsu. REFERENCE IN ENGLISH RÉFÉRENCE EN ANGLAIS The ocean environment and the living resources of the world. PUBLISHER- ÉDITEUR Nihon. suisan shigen hog (..1) PAGE NUMBERS IN ORIGINAL DATE OF PUBLICATION NUMÉROS DES PAGES DANS kyokai/ Japanese Society for the DATE DE PUBLICATION L'ORIGINAL preservation of Maritime resources. YEAR ISSUE NO. 30 to 80 VOLUME PLACE OF PUBLICATION ANNÉE NUMÉRO NUMBER OF TYPED PAGES LIEU DE PUBLICATION NOMBRE DE PAGES Not given DACTYLOGRAPHIÉES ••1111 .11! 95 REQUESTING DEPARTMENT Environment TRANSLATION BUREAU NO. 1101482 MINIST ERE-CLIENT. NOTRE DOSSIER N 0 BRANCH OR DIVISION TRANSLATOR (INITIALS) DIRECTION OU DIVISION Office of the Editor TRADUCTEUR (INITIALES) PIC PERSON REQUESTING T. Reid DEMANDÉ PAR Allan OCT - 4 1976 YOUR NUMBER VOTRE DOSSIER N 0 UNEDITe.D TRANSIATiON DATE OF REQUEST 17-081Q76 For inforrnaiion only DATE DE LA DEMANDE TRADUCriON REVISEE informalian s.zuloment 305.200-10-8 (REV. 2/68) 7830.21.029-6333 DEPARTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT BUREAU DES TRADUCTIONS if TRANSLATION BUREAU MULTILINGUAL SERVICES DIVISION DES SERVICES DIVISION MULTI LINGUES CITY CLIENT'S NO. DEPARTMENT DIVISION/URANCH VILLE NO DU CLIENT MINISTERE DIVISION/DIRECTION ,nvironment Office of the Editor Ottawa TRANSLATOR (INITIALS) BUREAU NO. LANGUAGE . NO DU BUREAU LANGUE TRADUCTEUR ( INITIALES) J^,VC 1101482 Jan<,nese OCT - 4 1976 iiTaritime Research Series 27. The ocean environment and the living resources of the worl.d. Kei^ji NASU. Japnnese Maritime Resources Protection Association. P30 IV. The ocean environment of the world. 1, Tr?PFaci_fs.c Ocean. The Pa.cific Ocean is the largest in the world. Its area is equivalent to those of the Atlantic and lndian Oceans together, being 165,246 x 1ob km2 This is about 50'r1o of the whole of the World. Ocean, and about 35^- of the total area of the globe. Compared with the Atlantic and Indian Oceans it is deep, the mean depth being 4,282 metres and at its point p31 of greatest depth, the Vityaz I)eep which is the cieepest'in the world, the depth is 11,034 metres. The volume is 707,5.55 x 106 km3, or about 54o/,, of' a l.l the o cean water in the world. UNEDITED Tf:AiVStAi"NOIJ For ir);arnTettion ariiv TRADUCTION N-,-)N REVJ.SL-E Informatiom sr4ufcmr.nP SOS-200-10-31 2 The surface currents are larg-ely to be attributed to the trade winds which prevail in middle to low latitudes and to the westerly winds which prevail in middle to high latitudes. In the low latitude zone between the limits of about 25° North and South, the main current flow is generally from east to west, and in the middle to high latitudes the prevailing current direction is from east to west. In each of the two hemispheres, centred on the middle latitudes, large scale perpetual high- pressure ring currents (anticyclonic gyres) are formed. p32 The principal ocean currents to be mentioned are the Kuroshio, the Oyashio, the West Wind Drift or the North Pacific Current, the California Current, the North and South Equatorial Currents, the Equatorià.l Counter Current, the Peru or Humboldt Current, the East Australian Current, and the Mindanao Current. In addition there are subsurface currents such as the Equatorial Undercurrent or Cromwell Current, and below the California and Peru Currents there are undercurrents directed towards the high latitudes. The depths of these currents are from 150 metres to several hundred metres. The volumes of these currents are shown* in Table IV - 110. The flow directions on the surface are shown in Figure IV - 1. ^ References are marked., but were not included in the copy provided to the translator. 3 'Figure IV - la. Surface currents of the Pacific Ocean. (Defant 1961). During northern hemisphere winter. 1. North equatorial current. 8. California current. 2. South equatorial current. 9. Tsushima warm current. 3. Equatorial counter current. 10. Mindanao current. 4. Kuroshio. 11. Peru current. 5. Oyashio. 12. East Autralian current. 6. North Pacific current. 13. Westerly wind drift current. (Antarctic ring current). 7. Alaskan stream. 150' 180' 150• 120" 90' Figure IV - lb. Surface currents at middle and low latitudes in the Pacific and Indian Oceans. (Defant 1961). Durinp: northern hemisphere summer. 1. North equatorial current. 4. Somali current. (south-west monsoon drift in the Indian Ocean). 5. West Australian current. 2. South equatorial current. 6. Mindanao current. 3. Equatorial counter current. 7. Peru current. 5 Table IV-1. The volume of flow in the main currents in the Pacific Ocean. Kuroshio 65 Sv Oyashio 15 North Pacific Current 35 California Current 15 North Equatorial Current 45 Equatorial Counter Current 25 Equatorial Under Current 40 Peru Current 18 Mindanao Current 18 to 31 East Australian Current 30 Alaskan Stream 3 to 8 A typical Pacific Ocean current, the Kuroshio, has its origin in the North Equatorial current which flows to the west in the North Pacific in the region from 8° to 18°N. When the extension of the North Equatorial current reaches the eastern side of the northern Philippines, the change of latitude brings the effects of the earth's rotation into play, and the current is intensified on the western side of the Pacific (Stommel 1948), becoming the so-called Western Boundary current, and this flows into the Japanese region as the Kuroshi.o . In the neiFhbourhood of the Ryukyu Islands the 6 Kuroshio splits, the main current going along the southern shore of Honshu and flowing to the east from eastern Honshu approximately following the 36° to 370 line. The split-off current mixes into the water mass of the East China Sea, goes northwards along the edge of the continental shelf, and flows through the Korean Straits into the Sea of Japan as the Tsushima warm current. As the Kuroshio flows eastwards from the south shore of Honshu, its width varies from place to place but is about 80 km, and the width of the region of high speed (3 to 5 knots) is estimated to be about 50 km. The depth of flow of the Kuroshio may reach more than 1000 m. The flow volume varies both locally and seasonally, but to the 1000 decibar level it is calculated to be about 65 Sv. There is a number of studies in which temperature is used to indicate the axis of flow of the Kuroshio. This temperature has regional variations but the temperature at the 200 metre level is generally taken to be 15°C which was reported by Uda (1964) and is in accord with the overall results of the investigations by Kawai (1970). To the east of Honshu, the Kuroshio proceeds eastwards through some remarkable meanders and becomes the Kuroshio P33 Extension which flows almost directly eastwards, its velocity and thickness diminishing in ways of which much remains in detail unknown. Since 1965 there has been a remarkable abundance of oceanographical research in the region of flow of the Kuroshio, conducted principally by the International Cooperative Survey 7 of Kuroshio (CSK) in which eleven North Pacific countries are grouped with Japan. For example, Yoshida et al (1967) predicted a unique easterly flowing Subtropical Counter Current on the basis of the theory relating ocean currents to the distribution of wind stress. The existance of this current was later confirmed in a report, based on CSK data, by Uda and Hasunuma. According to the report by Uda and Hasunuma, this Subtropical Counter Current exists in the same location as 12 the Subtropical Convergence , and it continues to be a local 13 current throughout the year . At the 100 m level it flows parallel to the 21 ° C to 24° C contours (centred around 22 °C to 23 00 ), and it reaches at least as far as the neighbourhood of 160 °E. The velocity of this current is 0.2 to 1.3 knots (with an average of 0.7 knots, 35 cm/sec), the width of the current is 60 to 180 km, the thickness of the current is estimated to be shallower than 300 m, and, on the basis of data obtained in the summer of 1965, the mean flow is calculated as 12 Sv, an amount very close to that of the Tsushima warm current. The oceanic currents in the neighbourhood of the Subtropical Counter Current are shown in Figure IV - 2. This region of the ocean is believed to be the spawning area of bluefin tuna (Thunnus thynnus) (Yabe et al, 1966) and of the bonito (Katsuwonus pelamis) (Mori, 1972), and is also believed to be the spawning area of the Japanese eel.