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지질해양학 (Marine Geology)담당교수:하호경 (hahk@inha.ac.kr)

• 수심측량(bathymetry): bathy: deep; meter: measure

Photographed in Histoire de la Marine française illustrée, Larousse, 1934.

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수심측정

• 챌린저호보고서(Challenger Report, 1880).

• 증기기중기는수심을알아보기위해줄의끝에무거운추를달아바닥에내리는데사용하였다.

• 492곳의수심측정, 중앙대서양산맥을확인

• 초기수심측정방법?–돌던지기/추달기

• 최근첨단관측방법– Echo sounding– Multi-beam Systems– Satellite Altimetry

수심측정

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시추기록

• 세계기록: 1994년 12.262 km 시추 (러시아의콜라반도)

• JOIDES Resolution: 수심 2.5 km깊이에서 2 km굴착성공 (1991년)

• 일본의새시추선 Chikyu 7 km까지가능

다중음향시스템(Multi-beam Systems)

Multi-beam systems provide more accurate measurements than echo sounders. Multi-beam systems collect data from up to 121 beams to measure the contours of the ocean floor.

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우리나라예

위성(satellite)을이용하다Satellite altimetry measures the sea surface height from orbit. Satellites can bounce 1,000 pulses of radar energy off the ocean surface every second.

1985-1990년까지 미해군에서운용한 Geosat위성이궤도에서해면의높이를측정하였다. 7 km/s로이동하면서매초수천번의레이더신호를송수신하면서고도(정확도: 0.03 m)를측정하였다. 해저에솟아있는지형은주변보다중력이커서주위의물을끌어당겨수면의굴곡이생기게된다.

Jason

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기원에따른퇴적물의분류

고위도에규조연니(Siliceous oozes)가풍부

해양퇴적물의분포도

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In contrast of carbonate, the dissolution rate of silica decreases with depth.

Most rapid dissolution occurs in surface water. If skeletal remains with silica (e.g. diatoms) can reach the bottom, they can be preserved.

Dead diatoms sink slowly, fecal pellets sink quickly.

Preservation of siliceous sediments in the deep ocean reflects the biologic fertility of overlying surface waters.

규조연니 (Siliceous oozes)

Mainly from skeletal remains of:

1) Diatoms

2) Radiolarian

해양으로퇴적물의공급

1) 하천 (Fluvial Inputs)--Rivers Discharge Sediment into the Ocean

2) 바람 (Aeolian Inputs)--Winds carry sediments from the continents into the ocean.

3) 생물 (Biological Inputs)--Marine organisms die and sink to the bottom.

4) 자생 (Authigenic Inputs)--Sediments that are formed in the oceans. Mainly metal rich materials near hydrothermal vents.

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Over geological time, mountains rise as lithospheric (crustal) plates collide, fuse, and subduct. Water and wind erode the mountains and transport resulting sediment to the sea. The sediments are deposited on the seafloor, where they travel with the plate and are either uplifted or subducted. Thus, the material is eventually made into mountains again.

퇴적물의순환

Weathering of granite leads to quartz and clay, the most common components of terrigenous sediment.

하천 Fluvial Sediment Input--Mississippi River

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바람 Aeolian Sediment Input--African Dust Storm

해저협곡

Submarine canyons are a feature of some continental margins. They cut into the continental shelf and slope, often terminating on the deep-sea floor in a fan-shaped wedge of sediment.

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저탁류의발생(right) 자메이카섬에서발생한저탁류(turbidity current). 저탁류는물의흐름이아니라중력에의해발생한다.

Avalanche-like sediment movement caused when turbulence mixes sediments into water above a sloping bottom are called turbidity currents.

이동속도계산: 해저케이블파손

Turbidity currents can transport terrigenous sediment down the continental slope.

Graded beds, called turbidites.

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Hydrothermal Vents

Hydrothermal vents are sites where superheated water containing dissolved minerals and gases escapes through fissures, or vents. Cool water (blue arrows) is heated as it descends toward the hot magma chamber, leaching sulfur, iron, copper, zinc, and other materials from the surrounding rocks. The heated water (red arrows) returning to the surface carries these elements upward, discharging them at hydrothermal springs on the seafloor.

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Hydrogenous (authigenic) Sediments:

Hydrogenous sediments precipitate directly from seawater.

Their formation is poorly understood, but it is thought to be associated with hydrothermal vent systems and mid-ocean ridge systems.

Most common hydrogenous sediments are manganese nodules.

Include evaporites and oolites.

Photo: S.J. Ju (KIOST)

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Manganese Nodules:Formed on concentric layers of manganese and iron oxides.

Form very slowly (1-10 mm per million years).

Found on large areas of the Pacific ocean.

Recent interest in economic development.

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Deep scattering layer (DSL)Diel vertical migration

• Organisms within the deep scattering layer undertake a daily migration to hide in deep, darker waters during daytime

Materials and Methods

q Environmental data• Surface Solar Radiation (SSR, W m-

2) from NCEP

• Sea ice concentration (SIC) from ECMWF

• Water temperature and CDW thickness (m, 0°C isotherm) from MicroCats.

• Phytoplankton biomass (Chl-a, mg m-3) from MODIS.

q ADCP data (RDI, 150-kHz Workhorse)• Burst rate and interval : 5 pings ensemble/15 min, 8-m from 250 to 540 m

• Acoustic intensity (mean volume backscattering strength, MVBS) and current speed

• The main depth of sound scattering layer (DMVBS, m)

La & Ha et al. (2015) ECSS

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Daily variability of backscatter

2010 (Month)

Dep

th (m

)

250300350400450500

MV

BS

(dB

)

−90

−85

−80

−75

−70

Dep

th (m

)

250300350400450500

Cur

rent

spe

ed (m

s )

0

0.05

0.10

0.15

Dep

th (m

)

320

370

420

470

520

Tem

pera

ture

(o

-1C

)

−1.5−1 −0.5

0 0.5 1 1.5

SIC

00.20.40.60.8

1

SSR

(W m

−2)(a)

(b)

(c)

(d)

(e)

0200400600800

Fig.5Fig.4

M A M J J A S O N D

SIC

Dep

th (m

)SS

RD

epth

(m)

Dep

th (m

)

2010 (Month)2010 (Month)

Dep

th (m

)

250300350400450500

MV

BS (d

B)

−90

−85

−80

−75

−70

Dep

th (m

)

250300350400450500

Cur

rent

spe

ed (m

s )

0

0.05

0.10

0.15

Dep

th (m

)

320

370

420

470

520

Tem

pera

ture

(o

-1C

)

−1.5−1 −0.5

0 0.5 1 1.5

SIC

00.20.40.60.8

1

SSR

(W m

−2)(a)

(b)

(c)

(d)

(e)

0200400600800

Fig.5Fig.4

M A M J J A S O N D

MV

BS

(dB

)C

urre

nt s

peed

(m

s-1

)Te

mpe

ratu

re( °

C)

March (Late summer) September (Late winter)

• Two representative time windows

Surface solar radiation

Sea ice concentration

Water temperature

Current speed

Acousticintensity

March 2010 (Day)

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 01

Dep

th (m

)

250300350400450500

Dep

th (m

)

250300350400450500

Dep

th (m

)

250300350400450500

Dep

th (m

)

320

370

420

470

520

SIC

00.20.40.60.8

1(b)

(c)

(d)

(e)

(f)

SS

R (W

m−2

)(a)

−90

−85

−80

−75

−70

−1.5−1 −0.5

0 0.5 1 1.5

11 12 13 14 15 16 17 18 19

MV

BS

(dB

)Te

mpe

ratu

re (

o C)

0100

200

300

Cur

rent

spe

ed (m

s )

0

0.05

0.10

0.15 -1

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 01

13 14 15 16 17 18 19 20 21

250300

350400450500

250300350400450500

250300350400450500

320

370

420

470

520

00.20.40.60.8

1

−90

−85

−80

−75

−70

−1.5−1 −0.5

0 0.5 1 1.5

September 2010 (Day)

MV

BS

(dB

)Te

mpe

ratu

re (

o C)

Dep

th (m

)D

epth

(m)

Dep

th (m

)D

epth

(m)

SIC

(b)

(c)

(d)

(e)

(f)

SS

R (W

m−2

)(a)

0100

200

300

Cur

rent

spe

ed (m

s )

0

0.05

0.10

0.15 -1

March 2010 (Day)

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 01

Dep

th (m

)

250300350400450500

Dep

th (m

)

250300350400450500

Dep

th (m

)

250300350400450500

Dep

th (m

)

320

370

420

470

520

SIC

00.20.40.60.8

1(b)

(c)

(d)

(e)

(f)

SS

R (W

m−2

)(a)

−90

−85

−80

−75

−70

−1.5−1 −0.5

0 0.5 1 1.5

11 12 13 14 15 16 17 18 19

MV

BS

(dB

)Te

mpe

ratu

re (

o C)

0100

200

300

Cur

rent

spe

ed (m

s )

0

0.05

0.10

0.15 -1

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 01

13 14 15 16 17 18 19 20 21

250300

350400450500

250300350400450500

250300350400450500

320

370

420

470

520

00.20.40.60.8

1

−90

−85

−80

−75

−70

−1.5−1 −0.5

0 0.5 1 1.5

September 2010 (Day)

MV

BS

(dB

)Te

mpe

ratu

re (

o C)

Dep

th (

m)

Dep

th (

m)

Dep

th (

m)

Dep

th (

m)

SIC

(b)

(c)

(d)

(e)

(f)

SS

R (W

m−2

)(a)

0100

200

300

Cur

rent

spe

ed (

m s

)

0

0.05

0.10

0.15 -1

Daily variability of backscatter

• March (Late summer)- Mean SSR and SIC: 77.4 W m-2 and 0.4- Clear DVM pattern with sun’s periodicity

q September (Late winter)- Mean SSR and SIC: 79 W m-2 and 0.9- Clear DVM pattern?

La & Ha et al. (2015) ECSS

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Cutting-edge technology

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Leg 1 Leg 2 Leg 3 Leg 4

East South West North

Tem

pera

ture

(o C)

Salin

ity (P

SU)

A)

B)

Surface Water > -0.5C

Mid-depth <-1.5 C

Modified CDW bottom water ~ 0 C or higher

Western FlankOutflow region

Air France flight 447 from Rio de Janeiro to Paris crashed several hundred miles off the northeastern coast of Brazil. On April 4, 2011, a search team led by the Woods Hole Oceanographic Institution (WHOI) located the wreckage of the Airbus jet some 3,900 meters (nearly 2.5 miles) below the surface of the Atlantic Ocean.