GERAKAN AIR LAUTGERAKAN AIR LAUT

MACAM MACAM GERAKAN AIR LAUTGERAKAN AIR LAUT

1.1. GELOMBANG.GELOMBANG.

2.2. PASANG SURUT.PASANG SURUT.

3.3. ARUS.ARUS.

GelombangGelombang Laut Laut

ANATOMI ANATOMI GELOMBANG GELOMBANG

Kecepatan merambat geolombangKecepatan merambat geolombang

(1) ..................... T

LC

C: kecepatan

L: panjang gelombang

T: perioda

Perairan dalam, d/L > 1/2Perairan dalam, d/L > 1/2

(4) ...................... 2

. 2

Tg

L

(6) ...................... 2

.

Tg

T

LC

Perairan dangkal, d/L < 1/20Perairan dangkal, d/L < 1/20

......(8).................... gdTL

(9) ...................... gdC

Di perairan dangkal, kecepatan gelombang dipengaruhi oleh kedalaman

GELOMBANG GELOMBANG MENDEKATI MENDEKATI PANTAIPANTAI

Perubahan Kondisi Gelombang

GELOMBANG PECAHGELOMBANG PECAH

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Types of breaking waves: (I) spilling breaker, (II) plunging breaker, and (III) surging breaker. Source: From Komar (1998).

Plungging breakersPlungging breakers

REFRAKSI REFRAKSI GELOMBANGGELOMBANG

Refraksi gelombang: pembelokan gelombang karena perubahan kedalaman air

Difraksi gelombangDifraksi gelombang

Pembelokan gelombang karena penghalang

JENIS-JENIS JENIS-JENIS GELOMBANGGELOMBANG 1 1

Jenis-jenisJenis-jenis gelombang menurut penyebabnya: gelombang menurut penyebabnya:1.1. GGeellomombbangang karena tiupan angin. karena tiupan angin.2.2. GGeellomombbangang internal. internal.3.3. SeicheSeiche (Standing wave) (Standing wave)..4.4. GGeellomombbangang badai. badai.5.5. GGeellomombbangang karena longsoran. karena longsoran.6.6. Tsunami.Tsunami.

Gelombang karena tiupan anginGelombang karena tiupan angin

Size and type of wind-generated waves are Size and type of wind-generated waves are controlled by: Wind velocity, Wind duration, Fetch.controlled by: Wind velocity, Wind duration, Fetch.

As wind velocity increases wave length, period and As wind velocity increases wave length, period and height increase, but only if wind duration and fetch height increase, but only if wind duration and fetch are sufficient.are sufficient.

Gelombang InternalGelombang Internal

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Schematic of a simple interfacial internal wave in a two-layer flow. Source: After Gill (1982).

Resonance amplifies the displacement at the nodes and Resonance amplifies the displacement at the nodes and occurs when the period of the basin is similar to the period occurs when the period of the basin is similar to the period of the force producing the standing waveof the force producing the standing wave..

Standing Waves

Penyebab TsunamiPenyebab Tsunami

FIGURE 8.7

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Sumatra Tsunami (December 26, 2004). (a) Tsunami wave approaching the beach in Thailand. Source: From Rydevik, (2004). (b) Simulated surface height two hours after earthquake. Source: From Smith et al., (2005). (c) Global reach: simulated maximum sea-surface height and arrival time (hours after earthquake) of wave front. Figure 8.7c can also befound in the color insert. Source: From Titov et al. (2005).

Tsunami

Jenis-jenis gelombang Jenis-jenis gelombang berdasarkan periode gelombangberdasarkan periode gelombang..

Pasang SurutPasang Surut

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The equilibrium tide. (a) Tide-generating force due to the moon or sun. (b) Earth-moon-sunalignment during spring tide, which also includes the case when the moon is opposite the sun Source: After NOAA (2008).(c) Alignment during neap tide. In (a), the F’s are the net gravitational acceleration at the antipodal, center, and sublunar points, and the T’s are the net tidal gravitational accelerations.

Efek pasang surut: Efek pasang surut: perubahan genanganperubahan genangan

VARIASI VARIASI PASANG SURUTPASANG SURUT

1.1. Var HarianVar Harian

2.2. Var BulananVar Bulanan

3.3. Var TahunanVar Tahunan

PASANG SURUTPASANG SURUTVariasi harian

PASANG SURUT – 4BPASANG SURUT – 4B

Variasi bulanan

PASANG SURUT – 4CPASANG SURUT – 4C

Variasi tahunan

ArusArus

Sirkulasi GlobalSirkulasi Global

SIRKULASI GLOBALSIRKULASI GLOBAL

KARAKTER KARAKTER SIRKULASI GLOBAL:SIRKULASI GLOBAL:

1.1. Melintasi zona iklimMelintasi zona iklim

2.2. Setiap samudera memiliki Setiap samudera memiliki pola aruspola arus tersendiri tersendiri

3.3. Setiap samudera memiliki Setiap samudera memiliki pola sirkulasi umumpola sirkulasi umum yang samayang sama

Faktor-faktor yang berpengaruh:Faktor-faktor yang berpengaruh:

1.1. Sistem arus utama: efek tiupan angin dan variasi Sistem arus utama: efek tiupan angin dan variasi densitas – krn beda temp dan salinitas.densitas – krn beda temp dan salinitas.

2.2. Arah arus: rotasi Bumi (efek Coriolis, spiral Arah arus: rotasi Bumi (efek Coriolis, spiral Ekman), kehadiran dan konfigurasi benua.Ekman), kehadiran dan konfigurasi benua.

EFEK CORIOLISEFEK CORIOLIS

SPIRAL EKMANSPIRAL EKMAN

Sirkulasi thermohalinSirkulasi thermohalin(SIRKULASI LAUT DALAM)(SIRKULASI LAUT DALAM)

Global Ocean Conveyor Belt SystemGlobal Ocean Conveyor Belt System

ARUSARUS DENGAN SEBAB KHUSUS DENGAN SEBAB KHUSUS

ARUS-ARUS DENGAN SEBAB KHUSUS:ARUS-ARUS DENGAN SEBAB KHUSUS:

1.1. Arus sepanjang pantai (longshore current)Arus sepanjang pantai (longshore current)

2.2. Arus rip (rip current)Arus rip (rip current)

3.3. Arus turbidArus turbid

4.4. Arus pasang surutArus pasang surut

5.5. ““Upwelling” dan “Downwelling”Upwelling” dan “Downwelling”

Longshore CurrentLongshore Current

Rip CurrentRip Current

Rip CurrentRip Current

Turbidity CurrentTurbidity Current

Upwelling dan DownwellingUpwelling dan Downwelling

Terima KasihTerima Kasih