Topic 3 The Water Planet

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Topic 3The Water Planet

• GEOL 2503
• Introduction to Oceanography

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Earth? Wouldnt Ocean be a better name?
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Water on the Earths Surface

• 71 of the Earth is covered by the oceans (139
  million square miles)
• More than one-half of the world's population
  lives within 60 miles (100 km) of the ocean.
• Volume of water in the oceans
• 1.37 billion cubic kilometers
• 329 million cubic miles

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How much water exists in the oceans?One estimate
of global water distribution

• Source Gleick, P. H., 1996 Water resources. In
  Encyclopedia of Climate and Weather, ed. by S. H.
  Schneider, Oxford University Press, New York,
  vol. 2, pp.817-823.

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Sphere Depths

• Assume Earth is a perfectly smooth ball
• The oceans would cover the globe to a depth of
  2646 meters (ocean sphere depth).
• Add all of the remaining water from the land and
  the atmosphere would increase the depth by 75
  meters to 2721 meters (total water sphere depth).

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The Global Ocean
Atlantic
Pacific
Indian
Continents can be considered as islands in a
single, world ocean.
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Ocean
The illustration shows how water evaporates from
the ocean, land, and rivers. The evaporated water
condenses in the cooler altitudes and falls to
the ground as rain or snow. See
http//ga.water.usgs.gov/edu/watercycle.html.
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The Hydrologic Cycle

• Reservoirsthe places in which water resides
• -oceans -lakes
• -rivers -groundwater
• -glaciers -atmosphere
• -snow packs -sea ice
• See previous slide and USGS web page

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The Hydrologic Cycle

• Hydrologic cycle typically know as the water
  cycle
• Evaporation water changes from a liquid to a gas
  as water vapor.
• Precipitation water that falls to the ground in
  many forms ice, snow, rain, hail.
• Excess water on land returns to the ocean by
  rivers

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What is Residence Time?

• Rate of removal from reservoirs must equal rate
  of addition to reservoirs
• Residence Timetime that water spends in any one
  reservoir
• Oceans oven have a residence time of thousands of
  years because of their size.
• Small reservoirs, such as the atmosphere, have
  short residence times, days to weeks.

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The Distribution of Land and Water

• 70 of Earths landmasses are in the Northern
  Hemisphere
• Most of this land lies in the middle latitudes
• The Southern Hemisphere is the water hemisphere
• Land in the water hemisphere is located in the
  tropical latitudes and the polar region

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The Oceans

• Three main oceans
• -Pacific Ocean
• -Atlantic Ocean
• -Indian Ocean
• The Arctic Ocean, considered the fourth ocean, is
  really an extension of the North Atlantic

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The Pacific Ocean

• Most surface area
• Largest volume
• Deepest in terms of single deepest spot
• Deepest in terms of average depth
• Circular shaped
• Covers one-third of the globe

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The Challenger Deep in the Mariana Trench is the
deepest spot in the world.
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The Atlantic Ocean

• Shallowest, rectangular shape
• Has the most shallow adjacent seas
• -Arctic Ocean
• -Gulf of Mexico
• -Caribbean Sea
• -Mediterranean Sea
• Covers about one-fifth of the globe

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The Indian Ocean

• Smallest area
• Very deep
• Triangular shaped
• Located mostly in the South Hemisphere
• Covers about one-seventh of the globge

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The Arctic Ocean

• Really a seaan extension of the Atlantic Ocean

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A Fifth Ocean?

• In the spring of 2000, the International
  Hydrographic Organization decided to delimit a
  fifth world oceanthe Southern Ocean (recall
  Balboa and the South Sea)
• It is the southern portions of the Atlantic
  Ocean, Indian Ocean, and Pacific Ocean.
• The Southern Ocean extends from the coast of
  Antarctica north to 60 degrees south latitude
• Northern boundary defined by an ocean current,
  not by land, so many do not consider this a true
  ocean

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The Hypsographic Curve

• The hypsographic curvegraph of the
  depth/elevation versus Earths area
• 29 of the Earths surface is above sea level
• 71 of the Earths surface is below sea level
• 80 of land is below 2,000 meters elevation
• 80 of the seafloor is deeper than 2,000 meters
• Hints at composition of crust

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Land and ocean are at different elevations
because they are made of different rocks. The
ocean floor is made of a denser rock than the
continents.
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Navigation

• Radar
• Loran
• Global Positioning System

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Radar

• Radio detecting and ranging
• Image is displayed on a radar screen when radio
  pulses are sent out, reflected from an object,
  and returned to the antenna

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Loran

• Long-range navigation
• Measures the difference in arrival time of radio
  signals from pairs of land stations

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Global Positioning System

• GPS
• Navigational satellites transmit digital codes
  through radio signals to ground receivers
• Receivers generate identical codes at the same
  time

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One of the GPS systems NAVSTAR satellites
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