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8/11/2019 Kuliah_1_14 Oseanografi Fisika
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BAHAN KULIAHM.K. ITK 521: OSEANOGRAFI FISIK
PJMK : Prof.Dr. Mulia Purba (10 kuliah)Anggota : Dr. I Wayan Nurjaya (5 kuliah)Praktikum : Tri Hartanto, Spi, MS
Mata Kuliah ITK 521: mata kuliah pada Mayor IKL,Program Pascasarjana IPB
Bagian OseanografiDepartemen Ilmu dan Teknologi KelautanFakultas Perikanan dan Ilmu Kelautan
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Oceanography : Graphos: ‘the description of’ , Ocean (lautan)
Oceanology : Logos: ‘the logic of’ or ‘the science of’, Ocean
Oceanography adalah ilmu yang mempelajari laut dalam segala
aspek dengan penekanan laut sebagai suatu lingkungan.
Aspek: fisika, kimia, biologi dan geologi
Ilmu dasar: diaplikasikan untuk menelaah sifat komponen lautan
• Fisika: Oseanografi Fisik (Physical Oceanography ),
• Biologi: Oseanografi Biologis (Bilogical Oceanography )
• Kimia: Oseanografi Kimiawi (Chemical Oceanography )
• Geologi: Oseanografi Geologi (Geological Oceanography )
(Kuliah # 1)
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Marine Sciences: Marine Physic, Marine Biology,
Marine Chemistry dan Marine Geology
Oceanography: pendekatan proses yakni pergerakan massa air pada
suatu habitat
Marine Sciences: pendekatan ilmu (sain) untuk menelaah karakter
aspek tsb di laut
Geofisika (geophysic): Mempelajari fisika dari bumi
Dinamika Fluida Geofisik (Geophysical Fluid Dynamics):
mempelajari dinamika gerak fluida pada skala yang dipengaruhi
rotasi putaran bumi
Hidrografi (Hydrography):
mempelajari penyajian peta-peta nautika: peta kedalaman, arus,
medan densitas internal lautan, pasang surut (pasut) dan proses fisik
yang berkaitan dengannya
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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
Tujuan: Mengetahui konsep dasar (teori) yg menjadi fondasi osenografi fisik.
Lebih spesifik:
(1) proses fisik yang mempengaruhi lautan terbuka dan pesisir,
(2) sifat-sifat fisik-kimia massa air,
(3) pergerakan dan gaya-gaya penyebabnya (arus, gelombang dan pasang
surut),
(4) keseimbangan bahang dan interaksi dengan atmosfir
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Ada 3 pilar dalam belajar dinamika lautan:
saling menyokong, tdk berdiri sendiri
(1) Teori: proses di laut berolak dan non-linier: teorinya kompleks:
penyederhanaan
(2) Observasi: jarang (sparse): waktu dan ruang
(3) Pemodelan numerik :
teori realistik,
interpolasi observasi,
prakiraan (forecast) perubahan cuaca,sirkulasi,
sebaran material.
pedekatan: lautan yang bersifat kontinu
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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 (1487 – 1488),
Christopher Columbus (1492 – 1494),Vasco da Gama 1497 – 1499),
Ferdinand Magellan (1519 – 1522)
Rute perdagangan global: Spanyol ke Filippina pada abad 16
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Eksplorasi lautan yang diikuti eksplorasi ilmiah oleh Eropah:
James Cook (1728 – 1779): Endeavour , Resolution, dan Adventure
Charles Darwin (1809 – 1882): Beagle
Sir James Clark Ross dan Sir John Ross: mensurvei the Arctic dan
Antarctic dengan Victory, Isabella, dan Erebus,Edward Forbes (1815 – 1854): 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
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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: Halley‟s charts of the trade winds,
Franklin‟s map of the Gulf Stream, and
Matthew Fontaine Maury‟s Physical Geography for the Sea.
2. Era of Deep-Sea Exploration: 1873 – 1914.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: 1925 – 1940.
Detailed surveys of colonial areas.
Examples: Meteor surveys of Atlantic, Discovery Expeditions.
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4. Era of New Methods: 1947 – 1956.
Long surveys using new instruments.
Examples: seismic surveys of the Atlantic by Vema
leading to Heezen‟s physiographic diagram of the sea floor.
5. Era of International Cooperation: 1957 – 1978.
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: 1978 – 1995.
Global surveys of oceanic processes from space.
Examples: Seasat, NOAA 6 – 10, NIMBUS – 7,
Geosat, Topex/Poseidon, and ERS – 1 & 2.
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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.
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Edward Forbes (Pioner dalam biology)
(1843)
„Theory Abyssal‟ tidak ada kehidupan pada kedalaman
“absolute darkness” >500 meter.
Ternyata dari pengambilan kabel pada kedalaman 3000 m:
ada kehidupan menempel pada kabel
Banyak penelitian untuk penemuan baru ini.Misalnya: deepsea expedition „Challanger‟ dan „Enterprise‟.
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Capaian Monumental (Milestones) dalam pengetahuan lautan
1685 Edmond Halley:
Meneliti: sistem angin di lautan dan arus, publikasi:
“An Historical Account of the Trade Winds, and Monsoons,
observable in the Seas between and near the Tropics, with an attempt to
assign the Physical cause of the said Winds” Philosophical Transactions, 16: 153-168.
1735 George Hadley:
Menerbitkan teori Angin Passat (the trade winds) berdasarkan
Conservation of angular momentum:
“Concerning the Cause of the General Trade-Winds”
Philosophical Transactions, 39: 58-62.
1751 Henri Ellis:
Peneliti awal: deep soundings of temperature in the tropics:
Ditemukan massa air dingin dibawah lapisan air hangat
Indikasi: massa air dalam berasal dari daerah kutub. purba@201417 (36)
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1769 Benjamin Franklin (as postmaster):
Made the first map of the Gulf Stream using information about ships
sailing between New England and England collected by his cousin
Timothy Folger (figure 2.7).
1775 Laplace: published his theory of tides.
1800 Count Rumford:Proposed a meridional circulation of the ocean with water sinking
near the poles and rising near the Equator.
1847 Matthew Fontain Maury:
Published his first chart of winds and currents based on ships logs.Established the practice of international exchange of environmental
data, trading logbooks for maps and charts derived from the data
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1930 F di f th W d H l O hi I tit ti
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1930 Founding of the Woods Hole Oceanographic Institution.
1942 Publication: The Oceans by Sverdrup, Johnson, and Fleming,
the first comprehensive survey of oceanographic knowledge.
Post WW 2 Founding of oceanography departments at state
universities: Oregon State, Texas A&M University, University of
Miami, and University of Rhode Island, and
the founding of national ocean laboratories such as the variousInstitutes of Oceanographic Science.
1947 – 1950 Sverdrup, Stommel, and Munk:
Publish their theories of the wind driven circulation of the ocean.
Together the three papers lay the foundation for our understanding
of the ocean‟s circulation
1949 Start of California Cooperative Fisheries Investigation of the
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1952 Cromwell and Montgomery:
Rediscover the Equatorial Undercurrent in thePacific
1955 Bruce Hamon and Neil Brown:
Develop the CTD for measuring conductivity and temperature as a
function of depth in the ocean
1958 Stommel publishes his theory for the deep circulation of the ocean.
196x Sippican Corporation invents the Expendable Bathy Thermograph
(XBT) now perhaps the most widely used oceanographic instrument.
1969 Kirk Bryan and Michael Cox:
Develop the first numerical model of the oceanic circulation
1978 NASA:
Launches the first oceanographic satellite: Seasat.
The program developed techniques used by generations of remotes
sensing satellites.
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1979 – 1981 Terry Joyce, Rob Pinkel, Lloyd Regier, F. Rowe and J. W.
Young:
Develop techniques leading to the acoustic-doppler current profiler
(ADCP) for measuring ocean-surface currents from moving ships, an
instrument widely used in oceanography.
1992 Russ Davis and Doug Webb:
Invent the autonomous drifter that continuously measures currents at
depths to 2 km.
1992 NASA and CNES:Develop and launch Topex/Poseidon, a satellite that maps ocean
surface currents, waves, and tides every ten days.
1997 Wally Broecker:
Proposes that changes in the deep circulation of the oceans modulatethe ice ages, and that the deep circulation in the Atlantic could
collapse, plunging the northern hemisphere into a new ice age.
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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 Earth‟s 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 (Fig 2.2) karena daratan terkonsentrasi di BBU
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70
45
35
65
Daratan > Lautan
Daratan ~ 2,5 %
Antarctic
0 – 65o S: daratan <25 %
dari
Lautan pada setiap 5o
54oS: Bouvet Is: salju abadi
dan es
Suhu udr: - 4o s/d +2,5oC
SPL: +1o s/d -1oC
54oU: Helgoland Is (German)
SPL: 3 – 18oC
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Akibat penyebaran daratan (benua) diperoleh sebaran lautan
(Tabel 2.1)
Sebagian lautan-lautan ini tidak jelas batasnya, tapi dipisahkan atau
diberi nama tersendiri karena sifat-sifat nya yang unik, walaupun
sifat-sifat tersebut saling mempengaruhi : terutama antarctic.
Karena bentuk yang tidak teruatur dari daratan perlu subdivisi
Grup besar adjacent seas : - Mediterranian: Large dan Small
- Marginal sea
Faktor utama morfologi bumi :
Dominasi peran laut makin nyata bukan hanya luas muka laut, tapi
juga volume.
Misalnya, volume darat diatas muka laut <1/10 vol. air laut. purba@201426 (36)
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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
Kedalam daratan rata-rata: 840 m
Latitude is the angle between the local vertical and the equatorial plane.
A meridian is the intersection at Earth‟s surface of a plane perpendicular to
the equatorial plane and passing through Earth‟s axis of rotation.
Longitude is the angle between the standard meridian and any othermeridian, 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.
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A d f l tit d i t th l th d f l it d t
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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 φ where φ is latitude
Thus 1o latitude = 111 km; and 1o longitude = 111 cos φ 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. Paul‟s 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 π Re/ (360 × 60) = 1.855 km, which is very
close to the official definition of the international nautical mile:
1 nm = 1.852 km.
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The Pacific Ocean
Extends northward from Antarctica to the Bering Strait
(Figure 3.2).
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 Capeon Tasmania 147o E.
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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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