OCEANOGRAPHY - Old Dominion Universityaverma/nsf/Oceanography IM 7...7 Seafloor Topography 25 min 8 Break 10 min 9 SOFAR Channel 60 min MarineTech 2009 - 2011 STEM Preparation through

MarineTech

2009 - 2011

STEM Preparation through Marine Engineering, Science and Technology Experiences

Dr. Alok. K. Verma Lean Institute - ODU

OCEANOGRAPHY

Instructional Module - 7

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MarineTech

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Description of Module

• The module deals with oceanic currents and factors which

causes it such as tides, Coriolis effect, winds, differences in

water density.

• We will also study about different types of currents in

ocean, wave characteristics, SOFAR channel, and seafloor

topography in detail.

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Dr. Alok. K. Verma Lean Institute - ODU 3

MarineTech

2009 -2011


Topics Covered

S No. Topic Estimated Time

1 Major Oceans 5 min

2 Tidal Currents 10 min

3 Surface Ocean Currents 45 min

4 Break 10 min

5 Coastal Currents 35 min

6 Global Conveyor Belt 10 min

7 Seafloor Topography 25 min

8 Break 10 min

9 SOFAR Channel 60 min

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Standards of Learning (SOL)

• Earth Science. 13 a, b, c, d

• Earth Science. 4 d

• Physics 9

• Algebra.2

• Algebra.11

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Oceanography

Oceanography is a branch of earth science that studies the ocean. It is also called as marine science. It is sub divided into various sub-domains.

Four sub-domains include:

• Biological Oceanography - Study of plants, animals of oceans.

• Chemical Oceanography - Study of ocean chemistry.

• Geological Oceanography - Study of geology of oceans.

• Physical Oceanography - Study of oceans physical attributes.

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1. Biological Oceanography -

Study to understand what

controls the distribution and

abundance of different types

of marine life.

2. Chemical Oceanography –

Study of ocean chemistry, the

behavior of the chemical

elements within the Earth’s

surface.

Oceanography Domains

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3. Geological Oceanography -

Study of geology of ocean

floors such as sedimentation

process, plate tectonics etc.

4. Physical Oceanography -

Studies ocean’s physical

attributes including

temperature-salinity

structure, waves, tides and

currents.

Oceanography Domains

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What are the major oceans of the world?

1. The Pacific ocean

2. The Atlantic ocean

3. The Indian ocean

4. The Southern ocean

5.The Arctic ocean

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Major Oceans

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The Pacific Ocean

• The pacific ocean is the largest among all the oceans (69.4 million square miles).

• The Mariana Trench is the deepest point (35,800 ft) in the Pacific Ocean and in the world.

• Temperatures of deep waters are intensely cold.

• Salinity is lowest among all the oceans.

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The Atlantic Ocean

• It is the second largest of the world’s

oceanic divisions with a total area of

41.1 million square miles.

• The Puerto Rico Trench is the deepest

point (28,374 feet) in the Atlantic

Ocean.

• The surface waters of Atlantic ocean

has very high salinity.

• The surface water temperatures are

warmer.

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The Indian Ocean

• The Indian Ocean is the third largest of

the world’s oceanic divisions with a

total area of 28 million square miles.

• The deepest point in this ocean region

occurs in the Java Trench with a depth

of 23,812 feet below sea level.

• It has the warmest ocean currents and

high salinity .

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The Arctic Ocean and the Southern ocean

• The Arctic ocean is the smallest and the

shallowest of all the five major ocean

divisions.

• It is located in the north polar region.

• The Southern ocean also known as the

Antarctic Ocean.

• The southern ocean is located in the

south polar regions partially covered

with ice.

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Major Oceans

The three major oceans are:

1. _______ - Largest, deepest, coldest, least salty.

2. _______ - Second largest, warm, salty.

3. _______ - Third largest, high salinity.

Match the following in which oceans the trenches are located

1. Mariana Trench - A. The Indian ocean

2. Puerto Rico Trench - B. The Pacific ocean

3. Java Trench - C. The Atlantic ocean

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Major Oceans

The three major oceans are :

1. The Pacific ocean - Largest, deepest, coldest, least salty.

2. The Atlantic ocean - Second largest, warm, salty.

3. The Indian ocean - Third largest, high salinity.

Match the following in which oceans the trenches are located

1. Mariana Trench - A. The Indian ocean (3)

2. Puerto Rico Trench - B. The Pacific ocean (1)

3. Java Trench - C. The Atlantic ocean (2)

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The ____________ Ocean near the north pole, and the ____________ Ocean near the south pole contain vast expanses of sea ice.

Major Oceans

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Major Oceans

The Arctic Ocean near the north pole, and the Antarctic/Southern

Ocean near the south pole contain vast expanses of sea ice.

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Color of Ocean Water

What makes the ocean water in

the picture to the left appears to

be in different colors?

Ans. Differences in the depth at

different regions.

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• The color of the water depends on the depth of the water.

• The depth of water determines how much light is reflected from the sea bottom.

• Therefore in shallow water, such as near a beach, the light reflected from the sand will make the water look lighter than in deep water (where little or no light is reflected from the bottom).

Colorful Ocean water

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An average ocean water sample with the mass of one kilogram

contains about 35 grams of dissolved salts. Four kinds of elements

make up 97 percent of the dissolved salts.

The four kinds of elements are:

- Chloride (Cl)

- Magnesium (Mg)

- Sulfate (SO4)

- Sodium(Na)

Composition of Ocean Water

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Class Exercise - 1

Composition of Ocean Water

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Ocean Currents

The term “Ocean Current”

describes motion of water.

Oceanic currents are driven by

- Coriolis Effect

- Winds

- Differences in water density

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Ocean Currents

There are two types of ocean currents:

1. Surface Currents (Red Color)

a. Makes up about 10% of all the

waters

b. These waters are the upper 400

meters of the ocean

2. Deep water currents (Blue Color)

a. Makes up the other 90% of the

ocean

b. Moves around the ocean basins by

density driven forces and gravity

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Coriolis effects results in the

deflection of major surface ocean

currents to the right in the

Northern Hemisphere (in a

clockwise spiral) and to the left

in the Southern Hemisphere (in a

counter-clockwise spiral).

Coriolis Effect

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Hands-on Activity-1: To simulate the Coriolis Effect by

drawing a "straight" line on a rotating disc

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Tidal Current

• Tides are the periodic rise and fall

of the ocean waters.

• When a tidal current moves toward

the land and away from the sea, it

“floods.”

• When it moves towards the sea

away from land, it “ebbs.”

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• Tidal Currents are affected by the relative positions of

the moon and Earth.

• When the moon and Earth are positioned nearest to each

other the currents are stronger than average and are

called “Perigean currents.”

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Tidal Currents

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When the moon and Earth are at their farthest distance from eachother (apogee), the currents are weaker and are called “Apogeancurrents.”

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Tidal Currents

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Tidal Current

• The Tidal currents are the type of currents which are affected by the interactions of the Earth, Sun, and Moon.

• Tidal Range: The difference between high and low tide water levels are called Tidal Ranges.

• When the Moon, Earth, and Sun fall in a straight line, we notice the highest Tidal Range. These are called Spring Tides.

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Tidal Current

• When the Sun and Moon form

a right angle there is a

smaller difference between

high and low tides (Lowest

Tidal Range).

• These are called Neap tides.

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Tidal currents

• Spring tides occur at the

time of the full moon or

the new moon.

• Neap tide comes twice a

month, in the first and

third quarters of the moon.

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Class Exercise-2

Tidal Ranges Compared to Moon Phases

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Tidal Currents

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1. Only the gravitational pull of the sun is important in

creating tides

A. True

B. False

2. The difference between high and low tide water levels are called Tidal Ranges

A. True

B. False

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1. Only the gravitational pull of the sun is important in

creating tides

A. True

B. False

2. The difference between high and low tide water levels are called Tidal Ranges

A. True

B. False

Tidal Currents

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Hydrometer

• Hydrometer is an instrument used

to measure the specific gravity

(relative density) of liquids.

• Specific gravity is the ratio of

density of substance to the relative

density of a given reference

material.

• Hydrometer is usually made of

glass and consists of a cylindrical

stem and a bulb weighted with

mercury to make it float upright.

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Hydrometer

• The operation of the hydrometer

is based on the Archimedes

principle that a solid suspended in

a fluid will be buoyed up by a

force equal to the weight of the

fluid displaced.

• The lower the density of a

substance, the further the

hydrometer will sink.

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Hands-on Activity-2: To measure the Relative Density

of water and salt water using a hydrometer.

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• Surface ocean currents, are driven

by a complex global wind system.

• If the Earth did not rotate on its

axis, the atmosphere would only

circulate between the poles and the

equator in a simple back-and-forth

pattern

Global Wind System

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• Circulating air is deflected because the Earth rotates.

• The air deflects toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere, resulting in curved paths.

• This deflection is caused by Coriolis effect.

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Surface Ocean Current

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Surface Ocean Currents

Warm air rises near equator and then cold air descends near 30

degrees North at North latitude and 30 degrees South at South

latitude.

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Surface Ocean Currents

As the air moves away from the equator the Coriolis effect

deflects it toward the right. It cools and descends near 30

degrees North latitude.

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• The descending air blows,

back toward the equator.

• A similar wind pattern occurs

in the Southern Hemisphere.

• These prevailing winds, are

known as the trade winds.

Trade Winds

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The remaining air (air

that does not descend at

30 degrees North or

South latitude) continues

toward the poles and is

known as the westerly

winds, or westerlies.

Westerlies

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Doldrums

• The Doldrums also called the “equatorial calms”, a nautical term for the intertropical convergence zone.

• Affects areas of the Atlantic ocean , the Pacific ocean , the Indian ocean that are within the inter tropical convergence zone(low pressure near the equator, where the prevailing winds are calm) .

• Hurricanes originate in this region.

• Notorious for sailors due to deadly calm winds.

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Class Exercise - 3

Coriolis Effect

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Coastal Currents

Coastal currents are coherent that are found in the region

between the coastline and the edge of the continental shelf

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Hurricane

• An atmospheric system characterized

by the rapid inward circulation of air

masses about a low-pressure center,

usually accompanied by stormy, often

destructive weather.

• A tropical cyclone is a storm system

characterized by a large low pressure

center and numerous thunderstorms that

produce strong winds and heavy rain.

• Tropical cyclones originate in the

doldrums near the equator, about 10

degrees away from the equator.

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http://library.thinkquest.org/03oct/01027/cyclone.jpg

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Hurricane

For the generation of hurricane the suitable conditions needed are

• Wind conditions – The upper, mid and low level wind

conditions should be light and should be flowing in the same

direction.

• Atmospheric layer conditions – Upper atmospheric layer can

be dry or moist, middle and lower level must be very moist.

• The latitude ranges should be 10N-30N and can be 10S-30S.

• The temperatures should be above 25 degree Celsius.

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Hurricane

• Hurricanes, typhoons and tropical cyclones are different names for the same type of storm.

• The only difference between them is the global area in which they form.

• A tropical cyclone is called a hurricane in the North Atlantic Ocean and South Pacific Ocean.

• A typhoon occurs in the Northwest Pacific Ocean.

• In the other parts of the world, these storms are called tropical cyclones.

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Typhoon

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Hands-on Activity-3: To study the impact of various

weather parameters on the formation of hurricanes.

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Crest, Trough, Amplitude, Wavelength, Wave Height

Wave Characteristics

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• Crest: The section of the wave that rises above the undisturbed position is called the crest

• Trough: That section which lies below the undisturbed position is called the trough

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Amplitude: It is the maximum positive displacement from

the undisturbed position of the medium to the top of a

crest.

Period: The time for one complete cycle of an oscillation of

a wave.52


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Wave Length: The wave length of a wave is the distance between

any two adjacent corresponding locations on the wave train. This

distance is usually measured in one of three ways:

- crest to next crest

- trough to next trough

- from the start of a

wave cycle to the

next starting point

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Label the wave diagram below with the following terms:

wavelength, wave height, trough, crest

trough

crest

wavelength

wave height


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Class Exercise-4

Calculating Wave Speed

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In a Longitudinal wave the particle displacement is parallel to

the direction of wave propagation

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Longitudinal Wave

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• Longitudinal Waves have

compressions and

rarefactions.

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Longitudinal Waves

• Compression: It's a region in Longitudinal Wave where the

particles are close together.

• Rarefactions: It’s a region in Longitudinal Wave where the

particles are far apart

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In a transverse wave the particle displacement is perpendicular to

the direction of wave propagation

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Transverse Waves

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Water waves are an example of waves that involve a combination

of both longitudinal and transverse motions.

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Water Waves

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Hands-on Activity-4: Wave Generator

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• As a wave moves toward the beach, different segments of the wave encounter the beach. They arrive at a slight angle, called the “angle of wave approach”.

• When a wave reaches a beach or coastline, it releases a burst of energy that generates a current, which runs parallel to the shoreline. This type of current is called a “long shore current”.

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Long Shore Currents

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A rip current, is a localized

current that flows away

from the shoreline toward

the ocean, perpendicular or

at an acute angle to the

shoreline.

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Rip Currents

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Upwelling

• Winds blowing across the ocean surface often push Water away from an area.

• When this occurs, water rises up from beneath the surface to replace the diverging surface water.

• This process is known as “upwelling”.

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Match the ocean currents with the following diagrams

A) Long shore Currents

B) Upwelling Currents

C) Rip Currents

Ocean Currents

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Match the ocean currents with the following diagrams

A) Long shore Currents

B) Upwelling Currents

C) Rip Currents

Ocean Currents

B

C

A65

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The deep-ocean currents are driven by differences in the

water’s density, which is controlled by temperature and

salinity .

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Global Conveyor Belt

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• In the Earth's polar regions ocean water gets cold, forming sea ice and leaves the salt behind, so the surrounding sea water gets saltier.

• As the sea water gets saltier, its density increases.

• Surface water is pulled in to replace the sinking water, which in turn becomes cold and salty enough to sink.

• This initiates the deep-ocean currents driving the Global Conveyor Belt.

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This shows the path of the global conveyer belt. The bluearrows indicate the path of deep, cold, dense water currents. The red arrows indicate the path of warmer, less dense surface waters

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Hands-on Activity-5: How Density Affects Water Currents in Ocean

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• Continental Shelf: A submerged

border of a continent that slopes

gradually.

• Continental Slope: The steep

descent of the seabed from

continental shelf to abyssal zone.

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Seafloor Topography

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• Abyssal planes: The flat or

gently sloping areas of the

deep ocean floor.

• Seamount : An underwater

mountain rising above the

ocean floor.

Seafloor Topography

Seamount

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• Continental Rise: The transitional area of

the continental margin between the

continental slope and abyssal plane.

• Ocean Trench: The deepest parts of the

ocean.

• Guyot: A flat topped under water

mountain.

Seafloor Topography

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Match the following

terms to their correct

letter in the diagram:

A

B

C

D

E

D

F

G

H

Island

Continental shelf

Continental slope

Abyssal plain

Seamount

Continental rise

Trench

Guyot

A.

B.

C.

D.

E.

F.

G.

H.

Sea Floor Topography

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SOFAR channel

What is SOFAR channel ?

• It is a layer of water depth in

ocean where the speed of sound

is at a minimum.

• Sound waves can get caught in

this channel and travel hundreds

of kilometers.

• The SOFAR channel is formed by

the interplay between changes in

ocean temperature and pressure

with increasing depth.

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In the upper most 1,000 m of ocean,

when vertical temperature changes are

very high, the speed of sound will be

dominated by temperature changes and

to a much lesser extent by salinity and

pressure.

SOFAR Channel

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Below the uppermost

1,000 m there is little

variation of temperature

and salinity with depth.

Pressure change becomes

the prime cause of sound

speed variability.

SOFAR Channel

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Class Exercise - 5

SOFAR Channel

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Overview

In this module we have learnt about:

1. Major Oceans

2. Tidal Currents

3. Surface Ocean Currents

4. Coastal Currents

5. Global Conveyor Belt

6. Seafloor Topography

7. SOFAR Channel

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THANK YOU

Contact Information:Alok K. Verma

Ray Ferrari Professor

Director – MarineTech Project

Director – Lean Institute

Old Dominion University

Phone (757) 683-3766

E-mail [email protected]

http://www.themarinetech.org

Documents

OCEANOGRAPHY - Old Dominion Universityaverma/nsf/Oceanography IM 7...7 Seafloor Topography 25 min 8 Break 10 min 9 SOFAR Channel 60 min MarineTech 2009 - 2011 STEM Preparation through