Radiation

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Introduction to Oceanography
Satellite data and pictures from NASA Figures and
tables from the textbook and from The Open
University/Pergamon
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THE SCIENCE OF OCEANOGRAPHY
"Most sciences take as province one class of
phenomena oceanography studies all classes of
phenomena in one place, the global ocean on
Earth." Nearly three quarters of the earth's
surface is covered by ocean, making our planet
the blue jewel of the solar system. The oceans
influence everything from the world's climate to
the presence of life on earth. Oceanography
is the study of the marine environment and its
interactions with the earth, the biosphere, and
the atmosphere. The study is prompted both by the
intellectual desire to understand how the oceans
move and how life develops in a salty, cold
environment, and the need to use wisely the
ocean's resources for the benefit of humanity.
Oceanography is an interdisciplinary science
integrating the basic principles of biology,
chemistry, geology, physics, geophysics,
mathematics, botany, zoology, meteorology, and
geography. The complex interweaving of scientific
disciplines is a challenge and an opportunity.
Oceanography's best practitioners enjoy crossing
these traditional scientific boundaries.
Oceanography is a young science, only decades old
as an integrated field of study. Its realm is
thought to be the oldest, indeed where life
began. The difficulties involved in exploration
have made the oceans earth's last great frontier.
Applications of high technology to oceanographic
instrumentation and vessels, increasingly
sophisticated computers, satellite remote
sensing, and innovative methodologies are rapidly
opening new possibilities for exploration and
research. Many questions remain to be answered.
Oceanography is divided into four areas of
emphasis BIOLOGICAL OCEANOGRAPHY examines the
processes governing the distribution, abundances,
and production of plants, animals, and nutrients
in the oceanic ecosystem. Emphasis is on
investigations of bacteria, phytoplankton,
zooplankton, and benthic organisms. Progress
entails identifying the patterns of variability
in space and time, determining the processes
producing and maintaining the patterns, then
quantifying the processes. CHEMICAL
OCEANOGRAPHY investigates the complex chemistry,
distribution and cycling of dissolved substances,
nutrients, and gases in seawater, the mechanisms
controlling them and their origins and fates.
MARINE GEOLOGY GEOPHYSICS studies marine
sediments (their formation, transport, and
deposition) ocean basin formation (plate
tectonics) processes governing shoreline
formation and the origin, structure, and history
of the oceanic crust and upper mantle. PHYSICAL
OCEANOGRAPHY endeavors to understand and predict
motion in the sea. Scales of motion range from
millimeters through tidal and current scales to
the great ocean gyres. The distribution of
physical properties (temperature, salinity, sea
ice) and air-sea interaction and its implications
for climate are fertile areas of research.
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CAREERS IN OCEANOGRAPHY
Oceanographers are predominantly employed in
research, both pure and applied. Their goal is to
produce a new understanding of an ocean system
and to explore the potential consequences of
human activities on the marine environment. They
are involved in sample and data collection, their
analyses and interpretation, and preparation and
dissemination of the results. Oceanographers work
at sea, on land, in laboratories, and at
computers. The profession may be entered with a
Bachelor's, Master's, or Doctoral degree -- the
more advanced the degree, the greater the level
of responsibility for initiating, designing, and
executing a scientific research project. A degree
in oceanography can also serve as a background
for a career in teaching, administration, marine
affairs, environmental studies, production,
inspection, computing, instrumentation
development, and statistical analysis. Most
oceanographers are employed in educational and
research institutions. Another large percentage
is employed by federal government agencies
Additional positions are available in research
and development for companies extracting and
harvesting the ocean's resources. An
oceanographer's duties are diverse, dictated by
the nature of the profession. Data are most often
collected at sea or from inland waters, but are
usually processed and analyzed in laboratories
and offices, often involving the use of
highly-specialized instruments and computers.
Oceanographers experience the exhilaration and
rigors of new discoveries made at sea, and return
to home port for months of data processing,
computer programming, analysis, writing,
budgeting, planning, and conferring. The work is
both rewarding and tedious, fascinating and
frustrating. Reports and scientific papers must
be written. Proposals need to be prepared to
obtain funding for the next phase of the
research. Instruments require adjustment and
redesign. Funds need to be budgeted and accounted
for. The next scientific cruise must be planned
and organized. Deadlines are constant. The hours
can be long and irregular. Career opportunities
are open to both women and men. Oceanographers
often travel around the world as part of their
research or its dissemination. They express a
high degree of job satisfaction.
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SI base units
http//physics.nist.gov/cuu/Units/index.html
Table 1.  SI base units --------------------------
---------------------------------------------- SI
base unit ----------------------------------------
-------------------------------- Base
quantity Name Symbol length meter m mass kilo
gram       kg time second s electric
current ampere A thermodynamic
temperature       kelvin K amount of
substance mole mol luminous intensity candela cd
-------------------------------------------------
-----------------------
1
Table 2.  Examples of SI derived
units --------------------------------------------
---------------------------- SI derived
unit ---------------------------------------------
--------------------------- Derived
quantity Name Symbol area square
meter m2 volume cubic meter m3 speed,
velocity meter per second m/s acceleration met
er per second squared   m/s2 wave
number reciprocal meter m-1 mass
density kilogram per cubic meter kg/m3 specific
volume cubic meter per kilogram m3/kg current
density ampere per square meter A/m2 magnetic
field strength   ampere per meter A/m amount-of-
substance concentration mole per cubic
meter mol/m3 luminance candela per square
meter cd/m2 mass fraction kilogram per kilogram,
which may be represented by the number 1 kg/kg
1 ------------------------------------------------
------------------------  
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Planet ocean
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Where is all the planet's water?   97.957 in
the oceans   1.641 in glaciers and ice caps  
0.365 in ground water   0.036 in lakes and
rivers   0.001 in the atmosphere
facts
CHECK http//earthobservatory.nasa.gov/Library/Wa
ter/
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Global biosphere
SeaWifs
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world global
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Ocean depth zones
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Nearly half of the Earth solid surface lies
within two quite well defined limits in altitude
(0-1 km) and depth (4-5 km), and a significant
proportion lies within a few hundred metres of
sea level
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Zones in the ocean
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Todays menu ..

• Introduction to Geophysics
• Oceanography
• Short BBC film -gt bits of oceanography and marine
  geophysics

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An Introduction to Geophysics

• Vikram Unnithan

Any questions -gt v.unnithan_at_iu-bremen.de Room
120, Research III
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Geosciences _at_IUB

• Oceanography
• Geochemistry
• Geology Sedimentary Geology
• Geophysics
• Astrophysics

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What is Geophysics

• Geophysics applies principles of physics to the
  study of the Earth
• Geophysical investigations of the interior of the
  Earth involve taking measurements at or near the
  Earths surface that are influenced by internal
  distribution of physical properties.
• Analysis of these measurements can reveal how the
  physical properties of the Earths interior vary
  vertically and laterally.
• By working at different scales, geophysical
  methods may be applied to a wide range of
  investigations from studies of the entire Earth
  to exploration of a localised region
• Geophysical surveying provides a rapid and cheap
  mean of deriving information on subsurface
  geology
• The alternative is to dig holes in the ground .

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Early Geophysics

• SEISMOSCOPE
• This Chinese seismograph
• dates from about 100 AD. An
• earthquake would upset a
• pendulum fastened to the base
• of the vase and knock a ball
• from the dragons mouth into
• the toads mouth to indicate
• the direction from which the
• seismic event came.

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Geophysics today
Magnetics
Plate tectonics
Seismics

• A basic amplitude volume interpreted along with
  three interactively processed seismic-attribute
  volumes (instantaneous amplitude, similarity, and
  phase). Each attribute volume enhances a specific
  event.

From Sheffield et al 2000 The Leading Edge
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Geophysical Techniques
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Seismic

• EXAMPLE USES
• Oil Gas Exploration

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Gravity
EXAMPLE USES Salt Dome Exploration New Basin
Reconnaissance Estimating Glacial
Cover Corroborating Seismic Refraction Military
Applications Isostatic Studies of the Earth
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Magnetics
EXAMPLE USES Estimating Basin
Thickness Determining Fault Type Locating Mining
Prospects Finding Buried Drums Evaluating
Ocean-Floor Spreading
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Radar
engineering and environmental geophysics
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Electromagnetics
EXAMPLE USES Finding Mineral Prospects Locating
Contaminant Plumes Finding Buried
Ordinance Locating Utilities Pipelines
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Resistivity

• EXAMPLE USES
• Stratigraphy (below)
• Plume detection (right)

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Useful ?

• Yes
• Commercial applications
• hydrocarbon, mining, navigation .. (applied
  sections)
• Military
• Acosutics, communications, exploration, others
  (they are all secret, so we dont really know but
  ..)
• Academic research topics
• Plate tectonics, seismology, and other
  theoretical sections
• Employment
• Just check out http//www.earthworks-jobs.com/

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Part 2

• Oceanography and Marine Geophysics
• Parts of the BBC Film The Blue Planet

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Seawifs
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Bathymetry
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Ocean depth zones
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Nearly half of the Earth solid surface lies
within two quite well defined limits in altitude
(0-1 km) and depth (4-5 km), and a significant
proportion lies within a few hundred metres of
sea level
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Zones in the ocean
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Plate tectonics

• Plate tectonics describes motion between thin,
  rigid shells, or plates
• The relative motion between the plates is taken
  up at their boundaries, which may be
  constructive, destructive, or conservative.
• Determines the shapes of oceans

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Evidences for plate movement

• Continental 'fit'.
• Fossils, Glacial deposits.
• Magnetic striping of the oceanic crust
• Seismicity map of the globe

Seismic belts outline plate boundaries
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Sea floor spreading
Symmetry of the magnetic anomaly with respect to
the ridge axis observation that age of rocks
increases with distance from the ridge
Sea floor spreading theory
The age of the ocean crust is mapped using
magnetic anomaly patterns. Magnetic anomalies
correspond to magnetic reversals that have been
dated by radiometric methods
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Why ?

• Internal structure of the earth
• Mantle convection

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Margins

• Constructive or divergent at which plates are
  created.

Destructive or convergent - at which plates
collide and one sinks beneath the other,
returning lithosphere to the interior.
conservative - at which plates slide horizontally
past each other.
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Examples of margins
Divergent boundaries
Convergent boundaries
Transform fault boundaries
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BBC Film Clips

• Shallow seas
• Seasonal seas (climate, wind) chapter 1, disk 2
• Tidal (tides) chapter 3, disk 2
• Ocean
• Open (currents, nutrients) chapter 4, disk 1
• Deep (plates, ridges) chapter 4, disk 1

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Tides, waves
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Upwelling
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Deep sea
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Radiation and Evaporation
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78 of the global precipitation goes into and
86 of global evaporation comes from the ocean
Amount of water in 103 km3 1 Sv 106 m3/s
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Salinity
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Sea surface temperature
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Although both atmospheric and oceanic motions are
ultimately powered by solar heating, the
important working substance of the global heat
engine is water
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Low/high pressure
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Atmosphere
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surface winds to blow towards the equator and
towards 60
The Intertropical Convergence Zone (ITCZ) refers
to a region of highest surface air temp and is
usually located near, but not necessarily on, the
equator
Three global wind regimes on earth...trades
(0-30), westerlies (30-60) and polar easterlies
(60-90)
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Most frequent wind directions
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Heat transfer
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January
July
Temperature difference between January and June
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Polar front and jet streams
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Ocean winds
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Energy balance
ENERGY BALANCE
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Earths energy balance represents the sum total
of all the interactions of radiant energy (both
sunlight and heat) with our planets climate
system. For the first time ever by a space-based
sensor, CERES can measure the radiant energy
reflected and emitted back into space accurately
enough to tell scientists which aspects of the
Earths climate systemsuch as clouds, aerosol
particles, surface reflectivityare changing, and
exactly how much these changes affect our
planets total energy budget. For scientists to
understand climate, they must also determine what
drives the changes within the Earth's radiation
balance. From March 2000 to May 2001, CERES
measured some of these changes and produced new
images that dynamically show heat (or thermal
radiation) emitted to space from Earth's surface
and atmosphere (left sphere) and sunlight
reflected back to space by the ocean, land,
aerosols, and clouds (right sphere).
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Radiation
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The atmospheric greenhouse effect. Shortwave
solar radiation passes through the clear
atmosphere relatively unimpeded, but longwave
infrared radiation emitted by the warm surface of
the Earth is absorbed partially and then
re-emitted by a number of trace gases such as
water vapor and carbon dioxide.
A portion of the sunlight that enters the Earth
system is reflected back into space, while the
remaining portion of the sunlight is absorbed by
the Earth system and stored as heat some is
absorbed in the atmosphere and some is absorbed
in the lands and oceans. A percentage of this
stored heat is emitted by the Earth system back
into space in the form of longwave energy. The
term "outgoing longwave radiation" refers to the
sum total of all the longwave electromagnetic
energy, or infrared radiation at wavelengths
ranging from 5 to 100 micrometers, that escapes
from the top of the Earth's atmosphere back into
space.
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clouds
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The shortwave rays from the Sun are scattered in
a cloud. Many of the rays return to space. The
resulting "cloud albedo forcing," taken by
itself, tends to cause a cooling of the Earth.
Because cumulonimbus cloud tops are high and
cold, the energy radiated to outer space is lower
than it would be without the cloud (the cloud
greenhouse forcing is large). But because they
also are very thick, they reflect much of the
solar energy back to space As a consequence, the
overall effect of cumulonimbus clouds is
neutral-neither warming nor cooling.
Longwave rays emitted by the Earth are absorbed
and reemitted by a cloud, with some rays going to
the surface. Thicker arrows indicate more energy.
The resulting "cloud greenhouse forcing," taken
by itself, tends to cause a warming of the Earth.
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High clouds warming effect
Cumulonimbus clouds (equator eg) neutral
The high, thin cirrus clouds in the Earth's
atmosphere act in a way similar to clear air
because they are highly transparent to shortwave
radiation (their cloud albedo forcing is small).
However they reflect outgoing longwave radiation
Different clouds
Low clouds cooling effect
Because cumulonimbus cloud tops are high and
cold, the energy radiated to outer space is lower
than it would be without the cloud (the cloud
greenhouse forcing is large). But because they
also are very thick, they reflect much of the
solar energy back to space As a consequence, the
overall effect of cumulonimbus clouds is
neutral-neither warming nor cooling.
Low stratocumulus clouds act to cool the Earth
system. Because lower clouds are much thicker
than high cirrus clouds, they are not as
transparent they do not let as much solar energy
reach the Earth's surface. (their cloud albedo
forcing is large). However, the thicker they get
the more emitted longwave radiation is reflected
back to earth, which can cause a warming.
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Rainfall
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Atmosphere and Ocean
7
Atmosphere and Ocean are held together by gravity
and irradiated by the Sun. Both are shallow
relative to the Earths radius. They share
a common boundary but are not a single coupled
system
NSA picture atmosphere
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Observational techniques
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Electromagnetic radiation travels easily through
the atmosphere (global network of meteorological
stations) But Water is almost opaque to
electromagnetic radiation. So Oceanographers are
restricted to indirect observation of a fluid
through which they can not see.
Remote sensing relies on electromagnetic
Radiation to convey information about the sea
to a sensor. Most electromagnetic Wavelength are
absorbed by the atmosphere But there are three
distinct wavebands, spectral windows at which
rays can pene- trate the atmosphere with less
interference. Visible wavebands, infrared and
microwaves
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Remote Sensing Techniques
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Energy penetration in ocean
Most solar energy is absorbed within few metres
of ocean surface Shorter wavelength penetrate
deeper.
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Cloud Aerosol formation
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2.4 droblets
Air injection into water by breaking waves
etc Bubbles rise Injection of small droplets into
atmosphere Smalles droplets form aerosols and
they remove water, dissolved salts and organic
matter from the surface of the ocean When water
evaporates the aerosols can act as nuclei for
cloud and rain formation
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Net flux
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ALBEDO
The sun's energy is emitted in all directions,
with only a small fraction being in the direction
of the Earth. Energy goes back to space from the
Earth system in two ways reflection and
emission. Part of the solar energy that comes to
Earth is reflected back out to space in the same,
short wavelengths in which it came to Earth. The
fraction of solar energy that is reflected back
to space is called the albedo. Low Albedos
ocean surfaces and rain forests have low albedos
and reflect only a small portion of the sun's
energy. High Albedos deserts, ice, and
cloudsreflect a large portion of the sun's
energy. A cloud usually has a higher albedo than
the surface beneath it, the cloud reflects more
shortwave radiation back to space than the
surface would in the absence of the cloud, thus
leaving less solar energy available to heat the
surface and atmosphere. Hence, this "cloud albedo
forcing," taken by itself, tends to cause a
cooling or "negative forcing" of the Earth's
climate.
Albedo
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Aerosols
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Aerosols are powders, or droplets, suspended in a
gas, with a typical particle diameter of about
one micrometer. they can act as a nucleus for the
condensation of water to make a relatively large
cloud droplet. But even light scattering that is
almost imperceptible to our eyes is enough to
affect the climate. The reflection of sunlight
from aerosol cools the planet to offset the more
familiar Greenhouse Effect. Once formed, aerosol
particles can collide and stick together, or they
can grow by further condensation from the vapour
phase.
Aerosols
October 13, 2001
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Surface currents
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Schematic chart of surface currents
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Coriolis1
Coriolis Force (CF) acts on winds and ocean
currents pushing them to the right in the
northern hemisphere and left in the southern
hemisphere
B. Coriolis Force 1. The Coriolis Force (CF) is
an apparent force that accounts for the effect
that the rotation of the earth has on fluids
moving on the earths surface -CF results from
the rotation of the spherically shaped earth 2.
The CF is very important in oceanography (and
atmospheric sciences) because it effects the
pathway of the ocean currents (and winds) -the
circular pattern of surface currents in the
subtropical gyres is a good example of the effect
of CF 3. An example of the effect of the
CF Launch a missile from the equator to the
north pole along a line of longitude at a speed
that is comparable to the earths rotational
speed. -Will the missile land on the same line of
longitude from which it was launched? -NO!...the
earth's rotation will cause the missile to fall
to the right of the target in the northern
hemisphere 4. This observed deflection occurs
because our reference frame is rotating, that is,
the earth rotation imparts an eastward velocity
to the missile when it was launched, i.,e., the
missile is traveling eastward with the same
eastward velocity of the surface of the earth at
that latitude
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Wind and di/convergence
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The large gyres
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• Crinoids
• ChimbaChimba
• Neptunas

MID TERM Wednesday, October 20 Tutorial Tuesday,
October 19 at 8PM in lecture hall
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Gulf Stream and Wind
Subtropical gyres between 10 and 40 degrees of
latitude
-Subtropical gyres are sites of downward water
motion (downwelling) to offset piling up
of surface water -Equator and subpolar gyre are
sites of upward water motion (upwelling) to
offset removal of surface water
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Ekman
See page 38, Fig 2.14
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Northern hemisphere
Up/downwelling
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Gulf stream rings
GULF STREAM
Page 63
The Gulf Stream is one of the strong ocean
currents that carries warm water from the sunny
tropics to higher latitudes. The current
stretches from the Gulf of Mexico up the East
Coast of the United States, departs from North
America south of the Chesapeake Bay, and heads
across the Atlantic to the British Isles. The
water within the Gulf Stream moves at the stately
pace of 4 miles per hour. Even though the current
cools as the water travels thousands of miles, it
remains strong enough to moderate the Northern
European climate. The image above was derived
from the infrared measurements of the
Moderate-resolution Imaging Spectroradiometer
(MODIS) on a nearly cloud-free day over the east
coast of the United States. The coldest waters
are shown as purple, with blue, green, yellow,
and red representing progressively warmer water.
Temperatures range from about 7 to 22 degrees
Celsius. Several clockwise-rotating warm core
eddies are evident north of the core of the Gulf
Stream, which enhance the exchange of heat and
water between the coastal and deep ocean. Cold
core eddies, which rotate counter clockwise, are
seen south of the Gulf Stream.
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Gulf stream direction
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Gulf Stream
Description A NASA satellite confirms that
overturning in the North Atlantic Oceana process
where surface water sinks and deep water rises
due to varying water densitiesspeeds up and
slows down by 20 to 30 percent over 12- to
14-year cycles. Scientists previously believed
that a change of this magnitude would take
hundreds of years, rather than close to a decade.
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Warm core/cold core eddies
Analogies
Formation of eddies
Similar processes of different scales
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Eddies and gyres
Large Gyre off Japan
This image shows eddies in the Gulf of Alaska as
measured by the TOPEX/Poseidon and ERS-2
satellites. Each eddy is indicated by the year
and location where it formed. Satellites
monitor movement and evolution of eddies
continuously. Using radar that sees through
clouds, the TOPEX/Posedion mission and the
European Remote-Sensing Satellite-2 (ERS-2)
produce maps of sea surface height. Since eddies
that are warmer than the surrounding water are
higher than the usual sea surface height they
appear on these maps. This image shows the
difference from normal sea surface height for the
Gulf of Alaska. Warm core eddies appear as red
circles.
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Tasmania
Tasmania
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East-West
Canadian East coast
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Eddy importance
Cold core eddies
Warm core eddies
  This schematic shows an idealized eddy in the
Gulf of Alaska. "Isotherms" are lines connecting
points of equal temperature, as on a weather map.
Warm, nutrient-rich coastal water spirals
clockwise, forming the core of the eddy.
Phytoplankton grow in the edges of the eddy near
the ocean surface, nourished by the nutrient-rich
eddy water. (Image by Robert Simmo
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Eddy formation topographic feature
Eddy formation at topographic features Agulhas
current
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Eddy description
Eddies
Eddies are rotating masses of water in the ocean
that typically form along the boundaries of ocean
currents. In the Gulf of Alaska, eddies of warm
water, filled with nutrients from shallow coastal
water, mix with the cold water off the
continental shelf.
Dimensions 10 - 200 km in diameter 10 -
1000 m Length scale decreases with distance away
from the equator (200 km at equator, 10 km in the
Arctic) Mesoscale eddies can be foundaway from
areas of high currents Small eddies of around 10
km in diameter are called Meddies (mostly anti
cyclonic)
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Meddies
Meddies
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MODE Exp
Ocean weather at 150 m water depth
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North Atlantic Oscillation
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Yearly fluctuations of the North Atlantic
Oscillation (NAO) affect weather. When the NAO
sustains either a positive or negative mode for a
long period, climate is affected. In the positive
mode, high pressure over the Tropical Atlantic
increases, and low pressure over Greenland
deepens. In the negative mode, high pressure
weakens over the Tropical Atlantic and the low
pressure in the North Atlantic moves south. Wet
and dry weather patterns result. (Image courtesy
of NOAA)
http//earthobservatory.nasa.gov/Study/NAO/
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El Nino
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http//www.sbg.ac.at/ipk/avstudio/pierofun/atmo/el
nino.htm
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ELNINO2
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2
These four views of the Pacific Ocean were
produced using sea surface height measurements
taken by the U.S./French TOPEX/POSEIDON
satellite. The images show sea surface height
relative to normal ocean conditions from March
1997 through June 1997. This evolutionary view is
providing oceanographers with more convincing
information that the weather-disrupting
phenomenon known as El Nino is back and getting
stronger. The white and red areas indicate
unusual patterns of heat storage in the white
areas, the sea surface is between 14 and 32
centimeters (6 to 13 inches) above normal in the
red areas, it s about 10 centimeters (4 inches)
above normal.
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El Nino text
El Niño A temperature anomaly Typically, the
Pacific trade winds blow from east to west,
dragging the warm surface waters westward, where
they accumulate into a large, deep pool just east
of Indonesia, and northeast of Australia.
Meanwhile, the deeper, colder waters in the
eastern Pacific are allowed to rise to the
surface, creating an east-west temperature
gradient along the equator known as the
thermocline tilt.             The trade winds
tend to lose strength with the onset of
springtime in the northern hemisphere. Less water
is pushed westward and, consequently, waters in
the central and eastern Pacific begin to heat up
(usually several degrees Fahrenheit) and the
thermocline tilt diminishes. But the trade winds
are usually replenished by the Asian summer
monsoon, and the delicate balance of the
thermocline tilt is again maintained.
Sometimes, and for reasons not fully
understood, the trade winds do not replenish, or
even reverse direction to blow from west to east.
When this happens, the ocean responds in a
several ways. Warm surface waters from the large,
warm pool east of Indonesia begin to move
eastward. Moreover, the natural spring warming in
the central Pacific is allowed to continue and
also spread eastward through the summer and fall.
Beneath the surface, the thermocline along the
equator flattens as the warm waters at the
surface effectively act as a 300-foot-deep cap
preventing the colder, deeper waters from
upwelling. As a result, the large central and
eastern Pacific regions warm up (over a period of
about 6 months) into an El Niño. On average,
these waters warm by 3 to 5F, but in some
places the waters can peak at more than 10F
higher than normal (up from temperatures in the
low 70s Fahrenheit, to the high 80s).   In the
east, as temperatures increase, the water
expands, causing sea levels to rise anywhere from
inches to as much as a foot. But in the western
Pacific, sea level drops as much of the warm
surface water flows eastward. During the 1982-83
El Niño, this drop in sea level exposed and
destroyed upper layers of coral reefs surrounding
many western Pacific islands.
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La Nina text
How La Niña Forms Researchers discovered that
during non-El Niño years, surface pressures tend
to be low over the warm waters of the equatorial
western Pacific as overlying warm moist air rises
and then diverges aloft. Over the colder waters
of the eastern equatorial Pacific, surface
pressures tend to be higher as converging winds
aloft contribute to the sinking of cool air. In
much the same way as a ball rolls down a hill,
air flows from high pressure in the east to low
pressure in the west along this equatorial
pressure gradient. This contrast in pressure is
what drives the trade winds, the prevailing
large-scale surface winds that blow from east to
west. As these winds blow along the surface of
the equatorial waters, there is a net transport
of ocean water in a westward direction. As this
occurs, cold, nutrient-rich water rises up (or
upwells) along the coast of South America to
replace the westward-moving surface water. This
upwelling brings nutrients to the surface waters
off the coast allowing the fish population living
in these upper waters to thrive. During La Niña
years, the trade winds are unusually strong due
to an enhanced pressure gradient between the
eastern and western Pacific. As a result,
upwelling is enhanced along the coast of South
America, contributing to colder than normal
surface waters over the eastern tropical Pacific
and warmer than normal surface waters in the
western tropical Pacific. Globally, La Niña is
characterized by wetter than normal conditions
west of the equatorial central Pacific over
northern Australia and Indonesia during the
northern hemisphere winter, and over the
Philippines during the northern hemisphere
summer. Wetter than normal conditions are also
observed over southeastern Africa and northern
Brazil, during the northern hemisphere winter
season. During the northern hemisphere summer
season, the Indian monsoon rainfall tends to be
greater than normal, especially in northwest
India. Drier than normal conditions are observed
along the west coast of tropical South America,
and at subtropical latitudes of North America
(Gulf Coast) and South America (southern Brazil
to central Argentina) during their respective
winter seasons.
101
The locations and extents of Exclusive Economic
Zones extending 200 miles offshore, within which
nations may claim right to all renewable and
non-renewable resources. Further seaward, the Law
of the Sea dictates how the resources are to be
shared
Figure 1
102
Figure 1. World total fish production in marine
waters, 1950-1993. Steadily increased for more
than 30 years, the world catch dropped sharply at
1990 appears to have peaked at a level between 85
and 90 million tons per year. FAO estimates that
catches of 70 of marine species have reached or
exceeded sustainable levels. (FAO Website
According to the Greenpeace webpage, the maximum
sustainable yield of marine fishes predicted by
FAO in 1994 should be 83 million tons. However,
the recorded total production for 1994 and 1995
exceeded 83 million tons each year. The ocean is
being slowly vacuumed of fish. The recent
collapse of Canadian cod population is a good
example.
Figure 2
103
We can group economically important marine
organisms in to five major families Demersal
fish. These are bottom-living fish such as cod
and haddock. These species tend to concentrate on
broad continental shelves, especially of the
North Atlantic. Pelagic fish. Pelagic fishes
are species that inhabit the water column, such
as herring, mackerel, anchovy, and tuna. The most
spectacular fish catches are made of
surface-shoaling pelagic species. Demersal fishes
and Pelagic fishes combines make up the majority
of the fish catch--about 72 million tons per
year. Crustaceans. This group consists of
bottom-dwelling species (crabs and lobsters) as
well as swimming invertebrates (krill,
shrimp)Crustacean fisheries are important to many
countries and regions, such as the Chesapeake Bay
of the U.S. About 4 million tons of this group
are harvested each year. Molluscs and
Cephalopods. These include various species of
squid, cuttlefish, and octopus. More cephalopod
stocks are harvested by the Japanese than by any
other nation. They also serve as an important
source of protein for many Mediterranean and
developing countries. About 2.5 million tons of
cephalopods are harvested each year. Marine
mammals. This group has been heavily exploited
for oil and meat, although they make a relatively
small portion of the global fish catch. Following
the commercial extinction of the large baleen
whales such as the blue, humpback, and fin,
smaller species such as the minke and sei are
being taken. Dolphins and porpoises are hunted
locally, particularly in some tropical
archipelagos.
www.sprl.umich.edu/GCL/ notes2/fisheries.html
Figure 3
104
Over 90 of the world's living biomass is
contained in the oceans, which cover 71 of the
Earth's surface. At present, we harvest about
0.2 of marine production. (You might think that
there is room for growth). Marine sources
provide about 20 of the animal protein eaten by
humans. Another 5 is provided indirectly via
livestock fed with fish. In Asia, about 1
billion people rely on fish as their primary
source of protein. Estimates suggest that
seafood production from wild fish stocks will be
insufficient to meet growing Global demand for
seafood products in the next century. The
fishing enterprise employs some 200 million
people worldwide.
Figure 4
105
Now, about 100 million metric tons/year are taken
from the sea. This figure seems to be
stabilizing. However, the harvest per capita has
grown little (see Figure 2). This implies that if
the current limit can not be increased, seafood
availability per person will shrink as population
expands. This will lead to rising prices.
Figure 5
106
Species Peak Year Peak Catch 1992
Catch Decline(in millions of tons) Percent Change
Pacific herring 1964 0.7 0.20 0.5 -71
Atlantic herring 1966 4.1 1.50 2.6 -63
Atlantic cod 1968 3.9 1.20 2.7 -69 South
African Pilchard 1968 1.7 0.10 1.6 -94
Haddock 1969 1.0 0.20 0.8 -80 Peruvian
anchovy 1970 13.1 5.50 7.6 -58 Polar
cod 1972 0.35 0.02 0.33 -94 Cape
hake 1972 1.1 0.20 0.9 -82 Silver
hake 1973 0.43 0.05 0.38 -88 Greater yellow
croaker 1974 0.20 0.04 0.16 -80 Atlantic
redfish 1976 0.7 0.30 0.4 -57 Cape horse
mackerel 1977 0.7 0.40 0.3 -46 Chub
mackerel 1978 3.4 0.90 2.5 -74 Blue
whiting 1980 1.1 0.50 1.8 -26 South American
Pilchard 1985 6.5 3.10 3.4 -52 Alaska
pollock 1986 6.8 0.50 1.8 -26 North Pacific
hake 1987 0.30 0.06 0.24 -80 Japanese
pilchard 1988 5.4 2,5 2.9 -54 TOTALS ---
51.48 21.77 29.71 -58 Source FAO
Figure 6
We can assemble a large amount of evidence that
points to the fact that our marine resources have
been over-exploited. First, there is a long list
of over-utilized resources.
107
Drift nets are a spectacular example of the new
more efficient fishing methods. These nets (50
feet by up to 65 km) kill all that they
encounter. They are banned by every fishing
country within its own territorial waters. The
drift nets cast every night in international
waters reaches about 48,000 km
Figure 7
108
wikyonos.seos.uvic.ca/people/ afanning/ENSO/fishin
g.htm
Annual catch of the Peruvian Anchovy Fishery from
1960-1990 Before 1950, fish in Peru were
harvested mainly for human consumption. The total
annual catch was 86,000 tons. In 1953, the first
fish meal plants were developed. Within 9 years,
Peru became the number one fishing nation in the
world by volume. This lead to a period of boom
years in Peru. 1,700 purse seiners exploited a
7-month fishing season. In 1972, the
combination of an El Nino year and overfishing
led to a complete collapse of the fishery.
Schematic diagram of El Niño effects on the
Peruvian Anchovy Fishery. During 'normal' years,
the trade winds move waters away from the coast
of Peru, bringing nutrient rich waters up from
depth to replace the waters moving offshore.
These nutrients provide nourishment for plankton
and serve as the basis of the food chain which
drives the Peruvian fishery. As the trade winds
relax during an El Niño, less nutrients are
brought from depth and the productivity of the
region is diminished. During the most severe El
Niños, the productivity may be so low that the
fishery collapses. A secondary complication
arises in that anchovy prefer a particular water
temperature, as the eastern Pacific warms, fish
may school together in pockets of cooler nutrient
rich waters, leaving them open for predation.
Figure 8
109
Climatic control of fish populations
Figure 9
110
Ocean productivity
Figure 10
Not all areas of the ocean are equally productive
111
Aquaculture
Figure 11
112
World Aquaculture Production by Species in
1998 Species 1998 Production Value   (thousand
tons) (US thousand ) FINFISH Silver
carp 3308 3086 Grass carp 2894 2655 Common
carp 2465 2828 Bighead carp 1584 1449 Crucian
carp 1036 834 Yesso scallop 856 1180 Nile
tilapia 794 893 Rohu 755 1945 Atlantic
salmon 688 2203 Catla 629 554 Mrigal
561 475 SHELLFISH Pacific cupped
oyster 3439 3269 Japanese carpet
shell 1427 1860 Blue mussel 500 259 CRUSTACEANS
Giant tiger prawn 578 3859 ALL SPECIES NOT
LISTED ABOVE 9350 19732 WORLD TOTAL 30863 47081
Weight includes shell Compiled by Worldwatch
Institute from UN FAO Yearbook of Fisheries
Statistics Aquaculture Production (Rome
2000).
Figure 12
113
Harvesting from salt pans
Mostly from India, Mexico, Spain, Italy
Figure 13
114
Manganese nodules
Ferro-manganese concretions were found in many
places of the seabed. The map, published in 1969
by Mc Kelvey, showed already the occurrence of
nodules in all the oceans, some have been found
also on the bottom of lakes
The problem of the genesis of the nodules is far
to have been resolved. Four processes have been
proposed by Bonatti (1986) "hydrogenous" a slow
precipitation of metallic component from the
seawater, that forms concretions with similar
content in iron and manganese and relatively high
grade in NiCuCo, "hydrothermal", producing
concretions generally rich in iron, poor in and
(NiCuCo), "diagenetic", giving by manganese
remobilization in the column and precipitation at
the sediment-water interface, nodules rich in
manganese and poor in iron and (NiCuCo), "halmyr
olitic", where the source of metallic components
is the weathering of basaltic debris by the
seawater.
Polymetallic nodules are small balls, dark-brown
colored and lightly flattened, 5 to 10
centimeters in diameter, which lay on the seabed
at 4.000 to 6.000 meters deep. Their wet density
is around 2 g/cm3 their water-content is 40 of
their dry-weight and their porosity is 50 .
Figure 14
115
Figure 15
116
OIL and Gas exploration
Figure 16
117
600
Offshore installations
Figure 17
118
Currently, there are up to 600 oil and gas
installations in the North Sea.
The Norwegian Petroleum Directorate (NPD) has
recently reviewed the petroleum resources base
and estimates total proven reserves on the
continental shelf at 38.5 billion barrels, the
largest of any North Sea country.According to the
NPD estimates, 72 are in the North Sea, 17 in
the Norwegian Sea and 4 in the Barents Sea. An
increasing number of finds are natural gas or
combined oil/gas fields. The majority of proven
Norwegian oil reserves are concentrated in or
near the Statfjord, Gullfaks, Oseberg and Ekofisk
fields.
1 t 7 barrel
Figure 18
119
The graph below shows how many millions of
gallons of oil each source puts into the oceans
worldwide each year 1 gallon 4 l
Figure 19
120
Dredging is a growing industry
Mining the sea sand
Sand has become an indispensable resource Sand
for glass Sand for concrete Sand for
fill Sand for beach renourishment
Figure 20
How sand can look like Lithogenous Sediments
Biogenous Sediments http//www.clas.ufl.edu/users/
gmead/ocbasins/sedtype.htm
121
The global market potential for ocean wave energy
is roughly equivalent to that of s mall-hydro or
wind energy, but with the potential to grow much
faster
Wave energy
Shore-Mounted Wave Energy Plant
A 25-yard-wide concrete bunker built on a
shoreline has an underwater opening that allows
water to slosh back and forth inside. The
resulting air currents are strong enough to turn
a turbine, which in turn generates electricity.
Its the same concept as a dam that uses water to
turn turbines, except in this case its the air.
Figure 21
122
Thermal energy
What is OTEC? OTEC, or ocean thermal energy
conversion, is an energy technology that converts
solar radiation to electric power. OTEC systems
use the ocean's natural thermal gradientthe fact
that the ocean's layers of water have different
temperaturesto drive a power-producing cycle. As
long as the temperature between the warm surface
water and the cold deep water differs by about
20C (36F), an OTEC system can produce a
significant amount of power. The oceans are thus
a vast renewable resource, with the potential to
help us produce billions of watts of electric
power. This potential is estimated to be about
1013 watts of baseload power generation,
according to some experts. The cold, deep
seawater used in the OTEC process is also rich in
nutrients, and it can be used to culture both
marine organisms and plant life near the shore or
on land.
Figure 22
123
Tidal energy
Tide mill
Rance barrage France Generates half a million
kilowatts of power on each tide
Figure 23
124
Medicines and biotechnology
Lophotoxin from seawhips Neuromuscular blocking
agent
Kelp as fertiliser, potash and algin, a
pharmaceutical and cosmetical product
Blood of the Horseshoe crab Detects bacterial
infection of human blood
Figure 24
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