ES10 - EARTH
Lecture 23- Remote Sensing and the Greenhouse
Effect
David Sandwell
Reading - Blue Planet p. 49-57 and p.
477-484
What do you see when you heat a block of tungsten to
say 2000 C?
Why
is it sometimes best to study the Earth from a satellite?
Why is CO2 called a greenhouse gas?
Why could the temperature of the Earth rise when fossil
fuels are burned?
- Blackbody radiation (Chapter 2, p. 49-55)
- electromagnetic spectrum
- physics of blackbody radiation
- radiation from the Sun and the Earth
- Satellite Remote Sensing
(no required reading but here is a good reference: Planet Earth:
The View from Space, by D. James Baker, Harvard Univ. Press, 1990,
ISBN 0-674-67070-1)
- applications
- classification of sensors
- types of orbits
- applications
- Greenhouse Effect and Global Warming (Chapter
18, p. 477-484)
- carbon cycle
- greenhouse effect
- anthropogenic CO2
- estimates of global warming
REMOTE SENSING
Most of the information gathered by remote sensing satellites
could be obtained by other means. For example if one wanted to measure
sea surface temperatures across the Gulf Stream between Bermuda and New
York, one could make the measurements from a cruise ship or aircraft. However,
if one wanted to measure sea surface temperature across the Antarctic Circumpolar
current then a satellite becomes a more viable platform. So the main advantages
of satellite remote sensing are:
- Global data set of uniform quality.
- Rapid data acquisition after satellite is designed, built
and launched.
- No need to obtain permission to collect data over hostile
countries.
- Can revisit a site on a regular basis for a long period
of time.
- Spacecraft provide stable platforms.
Of course the main disadvantages are the high cost of
a satellite system, the many years it takes to develop and launch a satellite
and the possibility of a launch or system failure.
Applications
- Meteorology
- Oceanography
- Glaciology
- Geology
- Geodesy
- Topography and cartography
- Agriculture, forestry, and botany
- Hydrology
- Disaster control
- Planning and land use
- Mineral and petroleum exploration
- Military applications
System Classification
- Active - illuminate object from spacecraft.
- Passive - rely on solar radiation reflected from
the surface or thermal radiation emitted from the surface.
- Imaging system - from a single location the spacecraft
must measure radiation intensity at many positions on the surface.
- Non-imaging system - either does not measure radiation
intensity (it may measure travel time) and/or it only measures radiation
from 1 point and so cannot build up a 2-D image even using the motion of
the spacecraft.
Examples:
David Sandwell
sandwell@geosat.ucsd.edu