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OCEAN LITERACY
OCEAN LITERACY
Essential Principles & Fundamental Concepts of Ocean Science
PRINCIPLE 1
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REVISION HISTORY
Date
Version
Revised By
Description
Aug 25, 2010
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VL
Original
ESSENTIAL PRINCIPLE 1
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The Earth has one big ocean
with many features.
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(a) The ocean is the dominant physical feature on our planet Earth
– covering approximately 70% of the planet’s surface. There is one
ocean with many ocean basins, such as the North Pacific, South
Pacific, North Atlantic, South Atlantic, Indian and Arctic.
One Ocean
The ocean covers approximately 70% of Earth with the five great
ocean basins (Atlantic, Pacific, Indian, Arctic, and Southern) holding
97% of Earth’s water. The water vapor the ocean releases into the
atmosphere returns as rain, sleet and snow, replenishing the planet
with freshwater. All life, including our own, is dependent on the
ocean. Understanding the ocean is integral to comprehending the
planet upon which we live.
Ocean Features
 Enormous, dynamic body of water
 Covers many “basins” (Atlantic, Pacific, Indian, Arctic & Southern)
 Basins are variably shaped – different contours, depths
 Basin sea floor moves due to tectonic plate movement
 One interconnected circulation system
 Sea level changes due to movement of the sea floor
 Water Cycle – interconnected water systems
 Enormous body of water but nonetheless finite & limited
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
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1(b) An ocean basin’s size, shape and features (islands, trenches, mid-ocean ridges, rift valleys) vary
due to the movement of Earth’s lithospheric plates. Earth’s highest peaks, deepest valleys and flattest
vast plains are all in the ocean.
1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(c) Throughout the ocean there is one interconnected circulation
system powered by wind, tides, the force of the Earth’s rotation
(Coriolis effect), the Sun, and water density differences. The shape
of ocean basins and adjacent land masses influence the path of
circulation.
One Interconnected Circulation System
The circulation system is driven by the:
• Wind
• Tides
• Coriolis Effect (force of Earth’s rotation)
• Sun
• Water density differences
Circulation Path Influenced By Ocean Basin Shapes
Shape of ocean basins & land masses influence the circulation path
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(d) Sea level is the average height of the ocean relative to the land,
taking into account the differences caused by tides. Sea level
changes as plate tectonics cause the volume of ocean basins and
the height of the land to change. It changes as ice caps on land
melt or grow. It also changes as sea water expands and contracts
when ocean water warms and cools.
Sea Level
Average height of the ocean relative to land
Sea Level Changes
• Plate tectonics change the volume of ocean basins
• Ice caps melt or grow
• Sea water expands and contracts
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(e) Most of Earth’s water (97%) is in the ocean. Seawater has
unique properties: it is saline, its freezing point is slightly lower than
fresh water, its density is slightly higher, its electrical conductivity is
much higher, and it is slightly basic. The salt in seawater comes
from eroding land, volcanic emissions, reactions at the seafloor, and
atmospheric deposition.
97% of Earth’s water is in the ocean
Seawater
• 96% pure water
• 3% sodium chloride (common salt or halite)
• 1% other elements (e.g. magnesium, calcium, potassium)
Seawater Properties
• it is saline
• its freezing point is slightly lower than freshwater
• its density is slightly higher that freshwater
• its electrical conductivity is much higher than fresh
• it is slightly basic (or alkaline)
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(f) The ocean is an integral part of the water cycle and is connected to all of the earth’s water reservoirs
via evaporation and precipitation processes.
Water Cycle
Water is
cycled and
recycled via
evaporation
(heating)
and
precipitation
(cooling)
processes.
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(g) The ocean is connected to major lakes, watersheds and
waterways because all major watersheds on Earth drain to the
ocean. Rivers and streams transport nutrients, salts, sediments and
pollutants from watersheds to estuaries and to the ocean.
Ocean Is Connected To Major Watersheds
The ocean is connected to major lakes, watersheds and waterways
because all major watersheds on Earth drain to the ocean.
Rivers & Streams Transport & Drain Substances To The Ocean
Rivers and streams transport nutrients, salts, sediments and
pollutants from watersheds to estuaries and to the ocean.
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1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES
1(h) Although the ocean is large, it is finite and resources are limited.
Water Is Finite
All the water we will ever have is already here on Earth in one form
or another (except possibly for ice-laden comets striking the Earth).
Freshwater Is Limited
Of the total supply almost 97% of the total is saline. Of the 3%
freshwater, ~69% is locked up in ice and glaciers while ~30% of
freshwater is in the ground. Only 1% is readily available for drinking.
Fresh surface-water sources, such as rivers and lakes, only
constitute 1/700th of 1% of the total water. Yet, rivers and lakes are
the sources of water most people use.
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