Introduction to oceanography

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Dr. IBRAHIM BATHIS K
http://solarboost.tech/team
IBK
ibrahimbathis@gmail.com

Introduction to Oceanography
▪ Were an alien intelligence to visit our solar system, they could conceivably
call our planet "Aqua" (or "Water") due to Earth's striking presence of
abundant liquid water.
▪ In fact, about 71% of Earth's surface is covered by the oceans, with
freshwater making up only about 1% of the total supply by volume.
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• Oceans cover an area of 139 million miles2 or 361 million km2 , and contain a
volume of about 1.37 billion km3 of water.
• All of this water is not distributed equally over the Earth;
• 61% of the Northern Hemisphere is covered by oceans, while
• in the Southern Hemisphere the oceans cover 81% of the surface area
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▪ Among the planets in the solar system, only Earth has an abundance of liquid
water at the surface, because of its fortuitous orbital distance from the Sun.
▪ (The planet Uranus and some of the moons of Jupiter, such as Callisto, are
thought to have abundant liquid water, but this water exists below a frozen
surface.)
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▪ Oceanography (compound of the Greek words ὠκεανός meaning "ocean" and
γράφω meaning "write"), also known as oceanology, is the study of the
physical and biological aspects of the ocean.
▪ It is an important Earth science, which covers a wide range of topics,
including ecosystem dynamics; ocean currents, waves, and geophysical fluid
dynamics; plate tectonics and the geology of the sea floor; and fluxes of
various chemical substances and physical properties within the ocean and
across its boundaries.
▪ An oceanographer is a person who studies many matters concerned with
oceans including marine geology, physics, chemistry and biology.
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▪ It may be said that the oceans are the last frontier for exploration.
▪ Ocean floor mapping surveys were first conducted only about five decades
ago.
▪ Detailed knowledge of the deep ocean and the ocean bottom has been
hindered by past technological barriers to exploration.
▪ The ocean can be a forbidding and hostile environment to human beings,
requiring specialized equipment and vehicles, some of which have been
invented only in recent times.
▪ To survive the cold, icy waters and the tremendous pressure of the overlying
water column, humans have relied on ocean surveying vessels, submarines,
specialized submersible diving craft, and robotic cameras to conduct modern
deep sea exploration.
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Introduction to Oceanography –
Oceanography is Interdisciplinary
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▪ As one of the earth sciences, oceanography is interdisciplinary in nature,
combining geology, geophysics, chemistry, biology, meteorology, and
engineering.
▪ Oceanography studies a wide diversity of topics, including, but not limited to:
the composition of sea water, geology of the ocean basins, aquatic life, the
physics of ocean waves, dynamics of hurricanes, coastal geological
processes, and marine mineral resources.
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The Importance of the Oceans
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1. Interaction with the atmosphere creates and influences
weather patterns.
2. The oceans are a major contributor to global climate patterns,
and can give us clues to past climate conditions.
A. Waves in water bodies are generated by winds that blow across the
surface.
B. Oceans provide humidity and moisture to the air, greatly influencing
weather. The most extreme example of this interaction is found in
hurricanes, which are born over warm, tropical oceans.
C. Water "smoothes outs" drastic changes in air temperature because of its
large heat absorbing capacity.
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2. Oceans are an oasis of life on earth, and they were the first cradle of life.
The oceans provide an ideal environment suitable for a great diversity of
living things.
A. Marine algae (microscopic aquatic plants) living in the oceans are the
base of the Earth's food chain. Through a biological process called
photosynthesis, these algae create their own food by taking energy
(sunlight), nutrients from minerals dissolved in seawater, and excrete
oxygen as a waste product, which directly supports most animal life.
B. Ocean water provides a natural barrier against deadly ultraviolet
radiation from the sun. For this reason, life evolved first in the oceans
rather than on land, because there was no ozone layer until the
atmosphere had been transformed from anaerobic to aerobic.
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3. Oceans are a carbon dioxide "sink"- they regulate the amount of carbon
dioxide in the atmosphere by dissolving large amounts of the gas in the water.
• The dissolved carbon dioxide, in turn, provides the raw material for sea
creatures to build shell material (calcium carbonate), which also acts as a
carbon dioxide sink.
• The oceans have played a key role in climate change through geologic time.
4 Oceans were responsible for creation of the atmosphere as we know it.
• Earth's atmosphere wasn't always composed of nitrogen and oxygen.
• The early atmosphere was probably composed of a very different mixture of
gases that would be poisonous to most forms of life: methane, ammonia,
carbon dioxide, and water vapor. Due to the lack of free oxygen, this was
called an anaerobic atmosphere.
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• Knowledge of oceanography is important for resource or energy extraction,
such as commercial fishing or aquaculture, oil and gas exploration, and clean
energy resources such as wind, wave, or tidal energy.
• The oceans are the major route for international trade through commercial
shipping, and are still a significant factor in the transportation of people
across the seas.
• But even the recreational user benefits from an understanding of the ocean,
from winds and currents for the casual sailor, tides and habitat conditions for
a fisherman, to wave patterns for surfers.
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Fun Facts About the Open Ocean
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• Oceans cover more than 70 percent of the Earth’s surface, and half of those
waters are at least 1.86 miles (3 km) deep.
• As far as we know, the ocean is 36,200 feet (11,000 m or almost 7 miles)
deep at its deepest point. On average, the ocean is about 12,100 feet (3,688
m) deep.
Eg The Mariana Trench
• Animals living in the bathypelagic zone or deeper never see sunlight. Some
organisms living there, such as vampire squid and humpback anglerfish,
produce their own light (Bioluminescent)
4. More than 99 percent of Earth’s inhabitable space is in the open ocean.
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5. The ocean is divided into five zones:
• Epipelagic zone, or upper open ocean (surface to 650 feet deep);
• Mesopelagic zone, or middle open ocean (650-3,300 feet deep);
• Bathypelagic zone, or lower open ocean (3,300-13,000 feet deep);
• Abyssopelagic zone, or abyss (13,000-20,000 feet deep);
• Hadopelagic zone, or deep ocean trenches (20,000 feet and deeper).
6. The ocean produces more than 50 percent of the air we breathe.
7. Humans have only explored 5 percent of the world’s oceans. However, it is
believed that humans have impacted every part of the ocean with waste and
chemical pollution.
Plastic are seen in the Marian trench
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5. The ocean is divided into five zones:
• Epipelagic zone, or upper open ocean (surface to 650 feet deep);
• Mesopelagic zone, or middle open ocean (650-3,300 feet deep);
• Bathypelagic zone, or lower open ocean (3,300-13,000 feet deep);
• Abyssopelagic zone, or abyss (13,000-20,000 feet deep);
• Hadopelagic zone, or deep ocean trenches (20,000 feet and deeper).
6. The ocean produces more than 50 percent of the air we breathe.
7. Humans have only explored 5 percent of the world’s oceans. However, it is
believed that humans have impacted every part of the ocean with waste and
chemical pollution.
Plastic are seen in the Marian trench
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How do we define the science of Oceanography?
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What is the best way to
observe the ocean?
How was the ocean observed so far…
What processes to observe
What technologies are available
How does our understanding of the ocean change our
future observation strategies?
What are the independent variables of the
ocean state?
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Oceanography is an
observationally driven field!
What are the independent variables
for the ocean?
What do they measure and what is
their use?
Geological: coastlines, bathymetry, sediment thickness
Physics: Temperature, horizontal velocity,
vertical velocity, Sea-surface height
Biology: Chl-a, Productivity, Zooplankton,
Phytoplankton, Fish and Egg counts, etc
Chemistry: Salinity, Carbon, Nitrogen, Iron, Oxygen…
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How was the ocean observed so far?
Lots of historical account of early
explorations –
Modern oceanography began with the Challenger Expedition between 1872 and
1876. It was the first expedition organized specifically to gather data on
a wide range of ocean features, including ocean temperatures seawater
chemistry, currents, marine life, and the geology of the seafloor.
HMS Challenger
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1895, almost a quarter of a century after the ship set sail.
The fifty thick tomes of the report, containing 29552 pages, were written by an
international galaxy of scientists and many of these reports still form a starting
point for specialist studies in oceanography.
4000 new species of animals taken by the trawls and dredges were documented and are
still referred to by scientists from all over the world.
The reports were the tangible evidence of the achievements of the Challenger venture,
but perhaps of much greater importance in the long term was the co-operation
between scientists of many countries, inspired by Wyville Thomson's leadership,
which set the young science of oceanography on the path to becoming the truly
international discipline that it is today.
HMS Challenger - some facts
Crew: 243
Scientists: 6
Duration of Expedition: 4 years
Distance sailed: 127,000 km (68,890 miles)
Number of sampling stations: 362
Number of depth soundings made: 492
Number of dredges taken: 133
Number of new species of animals and plants discovered: 4,700
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Other key milestones in Oceanography
1770’s: Ben Franklin refers to Gulf Stream as
“river in the ocean”
1830’s: Darwin’s HMS Beagle expedition
1847: Maury & Prince Albert of Monaco generate
first maps of ocean winds and currents
early 1900’s: advent of submarine brings new
technologies (echo sonar, magnetometer) → Navy $!
1920’s: Alfred Wegener proposes “continental drift”
1950-60’s: Heezen, Tharp, Menard discover mid-ocean ridges
1950’s: seafloor spreading proposed by Hess & Dietz
1965: Wilson proposes unified theory of plate tectonics
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International Observational Programs
Deep Sea Drilling Project - DSDP
1985, Joides Resolution Replace G.
Challenger
1968, Glomar Challenger
http://en.wikipedia.org/wiki/Soviet_submarine_K-129_(1960)
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The Joint Global Ocean Flux Study (JGOFS)
was launched in 1987 at a planning meeting in Paris
The Operational Goal of JGOFS :
Spatial Scale: regional to global
Temporal Scale: seasonal to interannual
1) Fluxes of carbon between the atmosphere-surface ocean-ocean
interior.
2) Sensitivity to climate changes
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The World Ocean Circulation Experiment
1990-1998
http://woce.nodc.noaa.gov/wdiu/
International Programme on Climate Variability and
Predictability, 1995-present
http://www.clivar.org
http://wcrp.wmo.int
World Climate Research Programme
http://www.clivar.org/publications/other_pubs/other_pubs.php
http://www-
pord.ucsd.edu/whp_atlas//pac
ific/p03/sections/printatlas/P
03_OXYGEN_final.jpg
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US Programs sponsors
Incredible amount of resources!
http://www.nsf.gov/
http://www.noaa.gov
http://www.onr.navy.mil/focus/ocean/habitats/default.htm
http://nasascience.nasa.gov/earth-
science/oceanography
e.g. GLOBEC http://www.pml.ac.uk/globec
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http://www.csc.noaa.gov/coos
U.S. Coastal Observing Systems
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Tools for ocean observing
http://www.whoi.edu/science/instruments/
very good
web-site→
1) Acoustic Doppler Current Profiler (ADCP): measure velocity in ocean by
pinging sound waves and analyzing the return wave
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2) ARGO floats: measure ocean T and S while drifting with ocean currents,
surface regularly to communicate with satellites to transmit data
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3) Air-Sea Interaction Meteorology (ASIMET): measure ocean T and S,
atmospheric wind, pressure, radiation, and precipitation; usually
on oceanic buoys or research ship
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4) BIOMAPPER: studies plankton via sonar, video, and environmental
measurements
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5) Conductivity-Temperature-Depth (CTD): measures T and S (density )in ocean
deployed off ship usually;
data fed back to ship in realtime
Niskin bottles sample ocean water at predetermined depths
“casts” can take many hours
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6) Gravity Corer: recover sediment core from ocean bottom
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7) Multi-beam Echo Sounder: measure ocean bathymetry with ship (10-5000m)
-like mowing the lawn: be sure
you have overlapping “swathes”
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8) MOCNESS: multiple open and closing net with an environmental sampling
system; used to collect plankton
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9) Magnetometer: measure magnetic field
in ocean
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10) Seafloor mapping from satellite radar
altimetry & ships soundings
Smith and Sandwell, 1997
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11) Ocean Bottom Seismometer: measure underwater earthquakes
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12) Sediment trap: collect falling sediments in ocean
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13) Alvin: a 3-person submersible that can dive to 4.5km
1977: discovered hydrothermal vents
A hydrothermal vent is a fissure on the seafloor
from which geothermally heated water
discharges.
Hydrothermal vents are commonly found near
volcanically active places, areas where tectonic
plates are moving apart at spreading centers,
ocean basins, and hotspots
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Remote Sensing/Satellite Imagery:
Geostationary Server - http://www.goes.noaa.gov
Satellite significant events: http://www.osei.noaa.gov
National Geophysical Data Center: http://www.ngdc.noaa.gov/ngdc.html
Technologies for ocean observing
Floating devices in the ocean:
Argo FLoats - http://www.argo.ucsd.edu
Drifter Programs: http://www.aoml.noaa.gov/phod/graphics/pacifictraj.gif
Submarines &
Remotely Operated Vehicles (ROVs) :
Amazing discoveries…
http://oceanexplorer.noaa.gov/technology/subs/rov/rov.html
Automated Underwater Vehicles (AUVs) :
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WORLD OCEANS & SEA
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WORLD OCEANS & Ocean topography
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• Oceans cover an area of 139 million miles2 or 361 million km2 , and contain a
volume of about 1.37 billion km3 of water.
• All of this water is not distributed equally over the Earth;
• 61% of the Northern Hemisphere is covered by oceans, while
• in the Southern Hemisphere the oceans cover 81% of the surface area
WORLD OCEANS & SEA
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Introduction to oceanography

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