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PENGANTAR OSEANOGRAFI

BDI 207

PERTEMUAN -2

OSEANOGRAFI

KOMPETENSI DASAR:

Setelah mengikuti kuliah mahasiswa dapat menjelaskan ruang lingkup, distribusi lautan dan menjelaskan sejarah eksplorasi lautan di dunia dan Indonesia

INDIKATOR :

Menjelaskan definisi , oseanografi

Membagi lautan berdasarkan luas

Menjelaskan penjelajahan lautan

Menjelaskan sejarah penelitian kelautan di Indonesia

Beberapa istilah:

Oceanology, Hydrography

Oceanography (Oseanografi)

Ocean = Laut

Graphos = graphy = gambaran

Oseanografi adalah gambaran tentang laut

Ocean = laut: logos = logy = ilmu

Oseanografi adalah suatu cabang

Ilmu yang mempelajari tentang laut

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Mengapa belajar fisika lautan:

Sumber makanan: proses

penyuburan laut

Digunakan manusia: bangunan,

pelayaran, rekreasi, perikanan

dll.

Lautan mempengaruhi cuaca

dan iklim global

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4 Bidang Utama Oseanografi:

1. Oseanografi Geologi

2. Oseanografi Fisika

3. Oseanografi Kimia

4. Oseanografi Biologi

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World Map of Earthquake Occurrence Episentrum of Earthquakes in Indonesia

Representasi seismisitas 3D di bawah busur kepulauan Indonesia (1964 2001). Data diambil dari katalog gempa oleh Engdahl et al. (1998), updated version.

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Chlorophyll Spring 2005 (MODIS Satellite)

Oceanography and Climate - longer timescales

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Gambaran Lautan (Statistik)

Earth is a prolate ellipsoid, an ellipse of rotation, with an equatorial radius of Re = 6, 378.1349 km (West, 1982) which is slightly greater than the polar radius of Rp = 6, 356.7497 km. The small equatorial bulge is due to Earths rotation. Bumi: water globe Kutub: daratan tertutup es, sehingga susah mencari batas daratan dan lautan, tetapi pembagian darat : laut lebih tetap yakni: 1 : 2,43 (29,2 % : 70,8 %). Distribusi tanah dan air: asimateri karena daratan terkonsentrasi di BBU

70

45

35

65

Daratan > Lautan

Daratan ~ 2,5 %

Antarctic

0 65o S: daratan

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Kalau seluruh daratan dan dasar perairan diratakan: 2400 m (mean sphere) depth. Kedalaman laut rata-rata 3800 m: merupakan bagian yang tipis dari bumi Bila dibandingkan dengan radius bumi adalah 1:1700 Mean elevation of land: 840 m Mean depth of sea : 3800 m Latitude is the angle between the local vertical and the equatorial plane. A meridian is the intersection at Earths surface of a plane perpendicular to the equatorial plane and passing through Earths axis of rotation. Longitude is the angle between the standard meridian and any other meridian, where the standard meridian is that which passes through a point at the Royal Observatory at Greenwich, England. Thus longitude is measured east or west of Greenwich.

A degree of latitude is not the same length as a degree of longitude except at the equator. Latitude is measured along great circles with radius R, where R is the mean radius of Earth. Longitude is measured along circles with radius Rcos where is latitude Thus 1o latitude = 111 km; and 1o longitude = 111 cos km. For careful work, remember that Earth is not a sphere, and latitude varies slightly with distance from the equator. Nautical miles and meters are connected historically to the size of Earth. Gabriel Mouton, who was vicar of St. Pauls Church in Lyons, France, proposed in 1670 a decimal system of measurement based on the length of an arc that is one minute of a great circle of Earth. This eventually became the nautical mile. A nautical mile should be 2 Re/(360 60) = 1.855 km, which is very close to the official definition of the international nautical mile: 1 nm = 1.852 km.

The Atlantic Ocean Extends northward from Antarctica and includes all of the Arctic Sea, the European Mediterranean, and the American Mediterranean more commonly known as the Caribbean sea The boundary between the Atlantic and Indian Oceans is the meridian of Cape Agulhas (20oE). The boundary between the Atlantic and Pacific Oceans is the line forming the shortest distance from Cape Horn to the South Shetland Islands. In the north, the Arctic Sea is part of the Atlantic Ocean, and the Bering Strait is the boundary between the Atlantic and Pacific.

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The Pacific Ocean Extends northward from Antarctica to the Bering Strait The boundary between the Pacific and Indian Oceans: Follows the line from the Malay Peninsula through Sumatra, Java, Timor, Australia at Cape Londonderry, and Tasmania. From Tasmania to Antarctica it is the meridian of South East Cape on Tasmania 147o E.

The Indian Ocean: Extends from Antarctica to the continent of Asia including the Red Sea and Persian Gulf (Figure 3.3). Some authors use the name Southern Ocean to describe the ocean surrounding Antarctica. Mediterranean Seas are mostly surrounded by land. By this definition, the Arctic and Caribbean Seas are both Mediterranean Seas, the Arctic Mediterranean and the Caribbean Mediterranean. Marginal Seas are defined by only an indentation in the coast. The Arabian Sea and South China Sea are marginal seas.

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Garis besar sejarah perkembangan pengetahuan lautan (oseanografi)

1. Pelayaran perdagangan:

Polynesia di Pasifik sejak 4000 BC Pytheas di Atlantik 325 BC,

Arab di S. India pada abad pertengahan.

Lebih mementingkan kejadian prasejarah.

2. Eropah modern:

voyage of discovery, misalnya,

Bartholomew Dias (14871488),

Christopher Columbus (14921494),

Vasco da Gama 14971499),

Ferdinand Magellan (15191522)

Rute perdagangan global: Spanyol ke Filippina pada abad 16

Eksplorasi lautan yang diikuti eksplorasi ilmiah oleh Eropah:

James Cook (17281779): Endeavour, Resolution, dan Adventure

Charles Darwin (18091882): Beagle

Sir James Clark Ross dan Sir John Ross: mensurvei the Arctic dan

Antarctic dengan Victory, Isabella, dan Erebus,

Edward Forbes (18151854): mempelajari kehidupan laut dalam.

Abad 20: survei dengan kapal lambat dan cakupan terbatas

menggunakan satelit

Studi sinoptik: cakupan luas dan sekaligus.

Juga untuk pertama kali dengan data satelit:

studi interaksi sistem biologi, kimia dan fisik mempengaruhi

lingkungan bumi.

Eras of Oceanographic Exploration 1. Era of Surface Oceanography: Earliest times to 1873.

Systematic collection of mariners observations of winds, currents,

waves, temperature, and other phenomena observable from the deck of

sailing ships.

Notable examples: Halleys charts of the trade winds,

Franklins map of the Gulf Stream, and

Matthew Fontaine Maurys Physical Geography for the Sea.

2. Era of Deep-Sea Exploration: 18731914.

Wide ranging oceanographic expeditions to survey surface and

subsurface conditions near colonial claims.

The major examples: the Challenger Expedition (Figure 2.1),

the Gazelle and Fram Expeditions.

3. Era of National Systematic and National Surveys: 19251940.

Detailed surveys of colonial areas.

Examples: Meteor surveys of Atlantic, Discovery Expeditions.

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4. Era of New Methods: 19471956.

Long surveys using new instruments.

Examples: seismic surveys of the Atlantic by Vema

leading to Heezens physiographic diagram of the sea floor.

5. Era of International Cooperation: 19571978.

Multinational surveys of oceans and studies of oceanic processes.

Examples: the Atlantic Polar Front Program,

the norpac cruises,

the International Geophysical Year cruises, and

the International Decade of Ocean Exploration.

Multiship studies of oceanic processes

6. Era of Satellites: 19781995.

Global surveys of oceanic processes from space.

Examples: Seasat, NOAA 610, NIMBUS7,

Geosat, Topex/Poseidon, and ERS1 & 2.

7. Era of Earth System Science: 1995

Global studies of the interaction of biological, chemical, and

physical processes in the ocean and atmosphere and on land

using in situ and space data in numerical models.

Examples: the World Ocean Circulation Experiment (WOCE)

(Figure 2.5) Topex/ Poseidon (Figure 2.6), SeaWiFS and

Joint Global Ocean Flux Study (JGOFS).

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Oseanografi sebagai Sains yang Sistematik

Mulai awal abad 19 bersama saudaranya meteorologi

Ada 3 faktor: mendorong kearah perkembangan yang cepat :

1 Pengukuran kedalaman untuk keperluan engineering:

- sejalan dengan penemuan elektromagnetik telegraphy

- meletakan kabel listrik pada dasar lautan.

2. Jalur pelayaran dan peta : angin, gelombang, badai, arus, kejadian

awan, distribusi es pelayaran lebih cepat dan aman.

3. Alasan (1) dan (2) kebutuhan teknis dan ekonomi.

Faktor ketiga dari dunia akademi Science.

Pada awalnya Biologist beranggapan tidak ada kehidupan pada

lapisan dalam lautan.

Edward Forbes (Pioner dalam biology) (1843) Theo