Earth ScienceSection 2.3Remote Sensing

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Objectives

•Compare and contrast different types of remote sensing.

•Discuss how satellites and sonar are used to map Earth’s surface and its oceans.

•Describe the Global Positioning System and how it works.

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Vocabulary

•satellite•remote sensing•Landsat satellite•TOPEX/Poseidon satellite•sonar•Global Positioning System•Geographic Information System

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Remote Sensing

•The process of gathering data about Earth using instruments mounted on satellites, airplanes, or ships is called remote sensing.

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Landsat Satellites

Landsat 7 SatelliteLandsat Image of

Lake Michigan

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Landsat Satellite• Landsat satellites

record reflected wavelengths of visible light and infrared radiation from Earth’s surface, and then computers convert the information into digital images.

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Uses for the Landsat Satellite• Landsat data are also

used to study the movements of Earth’s plates, rivers, earthquakes, and pollution.

The Bahamas from a Landsat Satellite

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TOPEX/Poseidon Satellite• The TOPEX/Poseidon

satellite uses radar to map features on the ocean floor.

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TOPEX/Poseidon Satellite• The satellite transmits

high-frequency signals to the surface of the ocean. The receiving device picks up the reflected echo. The distance is calculated using the known speed of light and the time it takes for the signal to be reflected.

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Uses for the TOPEX/Poseidon Satellite

• Scientists also use TOPEX/Poseidon to estimate global sea levels and study tidal changes and global ocean currents.

This is a TOPEX/Poseidon Image Mapping Wave Heights

This is a TOPEX/Poseidon Image of El Nino

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Sea Beam• Sonar is the use of

sound waves to detect and measure objects underwater.

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Sea Beam• Sea Beam technology

uses sonar to map the ocean floor from a ship.

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Sea Beam• A sound wave is sent

from a ship toward the ocean floor. A receiving device picks up the returning echo when it bounces off the seafloor.

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Sea Beam• A computer calculates

the distance from the ship to the ocean floor using the speed of sound in water and the time it takes for the sound to be reflected.

This is a type of Sea Beam called a Sidescan Sonar. A system like this was used to search for the Challenger

Space Shuttle

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Uses for the Sea Beam• Sea Beam technology

is used by fishing fleets, deep-sea drilling operations, oceanographers, volcanologists, and archaeologists.

A Sea Beam Image of the Mid Atlantic Ridge

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Global Positioning SystemThe Global Positioning System (GPS) is a satellite navigation system that allows users to locate their approximate position on Earth.

GPS Satellite

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Global Positioning System• These satellites can

also relay information to a GPS receiver about elevation, direction of movement, and speed.

GPS Satellites Orbiting the Earth

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Uses for GPS Technology• GPS technology is

used extensively in navigation by airplanes and ships.

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Uses for GPS Technology• GPS receivers detect

signals from the 27 GPS satellites orbiting Earth. Using signals from at least three satellites, the receiver can calculate location within 10 m.

• GPS receivers also help people in everyday life to find a destination or determine their current location.

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Geographic Information System• The Geographic

Information System (GIS) uses a worldwide database to create layers, or “themes,” of information that can be placed one on top of the other to create a comprehensive map.

GIS System – Bases in Dallas and Tokyo

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Geographic Information System• The Geographic

Information System (GIS) uses a worldwide database to create layers, or “themes,” of information that can be placed one on top of the other to create a comprehensive map. Examples of GIS Layers

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Geographic Information System

This is an Example of GIS Layers

This is a GIS Map of Ogden, Utah Showing the Route of a

Marathon