physical and geological processes in the oceans · what is oceanography (marine science) •is a...
TRANSCRIPT
SCOPE OF THE COURSE1. Introduction to Oceanography
2. General features of the oceans
3. Physical properties of seawater
4. Ocean circulation
5. Waves, Tides and Tsunami
6. Coastal Features (Beaches, estuaries and deltas)
7. Special topics: El Nino & Hurricanes
METHODS OF ASSESSMENT
• Practicals
• Quiz
• One mid-course test
• Final examination
Some Preference books for physical oceanography and
marine sciences in general
• Pickard, G.L., and Emery, W.J. (1990). Descriptive Physical Oceanography. An introduction, (5th Edition). Pergamon Press, Oxford, UK
• Gross, M.G. (1972). Oceanography, a view of the earth. Prentice-Hall, Englewood Cliffs
• Ross, M.A. (1995). Introduction to Oceanography. Harper Collins New York
• Pond, S. and Pickard, G.L. (1983), Introductory Dynamical Oceanography. 2nd Edition. Pergamon Press, Oxford, UK
• Bowden, K.F. (1983) Physical Oceanography for Coastal Waters. Ellis Horwood Limited, England. pp. 302
• Prager, E.J. and Earle, S.A. 2000. The Oceans. McGraw Hill. pp. 314
• Thurman, H.V. and Trujillo, A.P. 2004. Introductory Oceanography. Tenth Edition. Person-Prentice Hall. New Jersey.
• Websites
Focus of the first Lecture▪ Earth’s compartments: the Earth could be divided into
four main compartments
▪ Why study oceans
▪ What is Oceanography
▪ What is Physical Oceanography
▪ Oceans of the World
▪ Structure of Ocean floor
Water in the Biosphere
Volume (Thousands
of km3)
% of the Total
Oceans 1,370,000 97.2
Glaciers 29,000 2.1
Groundwater 4,000 0.62
Freshwater
lakes
125 0.009
Saline lakes 104 0.008
Soil moisture 67 0.005
Rivers 1.2 0.00009
Atmosphere 14 0.0009
Why study the oceans• The oceans is a continuous body of salt water.
• The ocean is a fluid in turbulent motion
• The oceans cover about 71% of the surface of the earth and land covers the remaining 29 %.
• The ocean affects many aspects of our environment, such as climate, weather and sea level.
• The oceans do not operate alone but together with the atmosphere, continents and ice-cover, they form a working machine, driven mostly by energy from the sun. Lesser amounts of energy derive from tides raised by the moon and sun and planets, and heat from the Earth’s interior.
• Oceans are an important source of food, energy, minerals, chemical, recreational and transportation resources.
08/04/2019
Role of ocean in regulating climate
• It stores most of the sun energy
• It transport heat around the globe, pumping warm water and air toward the poles, and cold water and air back to the tropics
• It regulates wind and precipitation patterns, such as cloud formation (evaporation), cloud movement (wind) and rain/snow formation (condensation)
• It controls freezing and thawing in polar regions through the sea ice formation/shrink
• It acts as a reservoir of carbon, soaking up carbon dioxide from the atmosphere
Ocean plays an important role in interaction with the atmosphere
Picture from Ocean Motion, NASA
What is Oceanography (marine
science)• is a scientific study of the ocean
• is the application of all disciplines and methods of science to understanding ocean phenomena.
• Oceanography is the science that studies the world's oceans, its waters and depths, how they move and how they play a part in the whole of our planet.
• Oceanography is the study of the deep sea and shallow coastal oceans: their biology, chemistry, geology and physics.
• Oceanography is not a single pure science but a combination of several.
ASTRONOMYTidal forces
GEOLOGYSea floor
tectonics, coastal
processes, sediments,
hydrologic cycles
PHYSICSThermal
properties of
water, sonar,
waves, currents
CHEMISTRYDissolved components,
temperature
dependence,
stratification/density,
chemical tracers
BIOLOGYFisheries, marine
adaptations
GEOGRAPHYWind belts,
weather,
coastal landforms,
World climate
OCEANOGRAPHY
An Interdisciplinary Science
What is Physical oceanography
• the physical characteristics of the water in the ocean,
such as the motion of the water from the molecular
level to the global scale, including ocean currents,
eddies, waves, and tides. Interaction of the ocean
with the atmosphere is another important area of
inquiry.
• studies all forms of motion in the ocean.
• Synoptic Oceanograpy– Observation, preparation
and interpretation of oceanographic data
• Dynamic Oceanography – applies the laws of physics
to ocean, regarding it as a fluid acted upon by forces
and solve the resulting mathematical equations
Distribution of water on the Earth’s surface
Atlantic Ocean 25%
Indian Ocean 20%
Pacific Ocean 52%
Ice 2%
Atmosphere, lakes and
rivers
0.01%
Ground water 0.625%
Ocean of the world
• The three major bodies of water: the Atlantic, Indian
and Pacific Oceans
• The Pacific Ocean, the largest and deepest,
constitutes about 43% of the oceanic area of the
world, and is larger than all land areas combined.
Also having both a surface area and a volume
greater than the other oceans combined
• The Southern Hemisphere is dominated by ocean
(80.9%) because of the connection of the ocean
basins around Antarctica. Although the northern
hemisphere contain most of the land, it is still
dominated by ocean (60.7%)
Different characteristics of major
oceans
• Indian Ocean is the smallest, youngest, and physically most complex of the world’s three major oceans.
• Indian Ocean has the fewest marginal seas of the major oceans
• In the Northern Hemisphere it is landlocked and does not extend to Arctic waters
• It has fewer islands and narrower continental shelves.
• It is the only ocean with an asymmetric and, in the north, semiannually reversing surface circulation.
• The Atlantic is relatively narrow and has by far the largest drainage area.
Smaller water bodies• Sea: Is also a portion of an ocean which is not divided
off by land but has local distinguishing oceanographic characteristics
• Mediterranean Sea, Caribbean Sea, Sea of Japan, Bering Sea, Norwegian Sea; Labrador Sea; Tasman Sea, etc
These are bounded by land or by island chains
Have restricted connections with ocean and thus, have restricted exchange of water with open ocean
• Average depth of oceans – 3 700m
• Average depth of seas - 1200 m
Provinces of the ocean floor
• The major oceans are structured into:
i) Continental margins – shallow-water areas
close to continents
ii) Ocean basins – deep-water areas farther from
land and Mid- ocean ridges, which are
shallower areas near the middle of an ocean
Continental margins
• Continental shelf – flat zone extending from the
shore beneath the ocean surface to a point at
which a marked increase in slope angle occurs,
called the shelf break.
• Usually flat and relatively featureless because
of marine sediment deposits but can contain
coastal islands, reefs and raised banks
• Underlying rock is granitic continental crust – so
geologically part of continent
• The average width of the continental shelf is
about 70 km
Continental margins
• Continental slope – lies beyond the shelf break.
Total relief is similar to that found in mountain
ranges on the continents
• Continental Rise – is a transition zone between
the continental margin and the deep ocean floor
comprised of a huge submerged pile of debris
• Features of the ocean basin – Abyssal plains,
seamounts and trenches, and the Mid-ocean
ridge
Topography of the ocean floor – Hypsographic
Curve• Hypsographic Curve-shows the relationship between height of
the land and the depth of the oceans. It shows amount of Earth’s surface above or below any selected elevation or depth
• In the past, the ocean bottom was considered to be a smooth
• bi-modal distribution in the elevation distribution. It is apparent that most of the earth's surface is covered by deep basins and low lying land
• The frequency plot shows that only about 29% of the Earth’s crust projects above the sea level. This means that we humans inhabit and know most about the area of the Earth that is unrepresentative of its surface, the dry land! These data also reveal that mountains and deep-sea trenches are uncommon landforms
• The average depth of the ocean is about 3.7 km and the deepest areas, in the Marianas and Philippine trenches, are over 11 km deep.
• Average height of the land is 840 m and the highest point is 8850 meter – Mt Everest