Oceanography From Space
At first thought, studying the oceans from
space seems to be a bizarre idea.
Space observation helps oceanographers
do research with manned and unmanned
space systems. The space systems can be
satellites and/or space shuttles that
observe various features of the ocean
such as sea-surface winds, sea-surface
temperatures, waves, ocean currents,
frontal regions, and sea color.
Technological advances have greatly
improved the ability of oceanographers to
gather and use information that is
received. Oceanography as viewed from space
has and will become more and more
valuable as we begin to understand more of the
world's oceans. Projects Space
oceanography uses a number of different sciences
to research the oceans that
include physics, geology, biology, chemistry, and
engineering (Cracknell 13).
This is evident in the projects that send satellites
into space for
observation of our oceans. In 1992, the Topex/Poseidon project
was launched
to observe the interaction between the ocean and the atmosphere
(Cracknell
17). The Topex/Poseidon mission is to gather information about
sea level heights
and ocean currents (Cracknell 17). The Topex/Poseidon
orbits above the earth at
840 miles and has a 10-day repeating cycle in
which it takes pictures of all of
the earth (Cracknell 17). Information about
the how the sea level changes can
tell scientists that there are changes in
ocean currents and in climate patterns
(Cracknell 25). This information is
valuable to both oceanographers and
meteorologists because it gives
information about the phenomena, El Nino. Figure
1 is a picture of how
the Topex/Poseidon works. Figure 1(NASA) The Topex/Poseidon
receives
information as to what it is supposed to do from a beacon on earth.
The
satellite then gathers the information it is supposed to gather and then
sends
it to the beacon on earth. The beacon on earth processes this
information so
that scientists can use it. As the Topex/Poseidon nears the
end of observation
new developments are being made to continue with similar
work. Jason 1 is an
observation satellite that will look at extending
research about the interaction
of oceans with the atmosphere, improving
predictions about the climate, continue
to monitor El Nino, and observe ocean
eddies (Cracknell 26). These satellites
are leading the way to a better
understanding of our oceans as well as weather
on planet earth. History
Observations of oceanographic features with pictures
were first realized with
the invention of the camera (Pinet 181). Soon after the
invention of the
Camera, hot air balloons were used to take high altitude
pictures of the land
and sea, for mapping purposes (Pinet 181). In World War II,
pilots took
pictures of large areas of land that were used to develop strategies
in the
war (Pinet 181). At the beginning of the space age, just after World
War
II, rockets (although never in orbit) used movie cameras to
photograph the
surface (Pinet 182). The first manned shuttles took pictures
of Earth and
realized there were many observations of the oceans to be made
(Pinet 182). Soon
remote sensing came into action as satellites were sent
into orbit (Pinet 182).
Process of Remote Sensing Remote Sensing involves
two types of instruments,
passive and active (Gautier 58). Passive
instruments detect natural energy that
is reflected or emitted from the Sun
(Gautier 59). Scientists use a variety of
passive remote sensors such as a
radiometer, imaging radiometer, and
spectrometer. A radiometer measures the
intensity of electromagnetic radiation
in a band of wavelengths in the
spectrum (Gautier 59). The spectrum is a measure
of the visible, infrared
(heat), and microwaves emitted from the Earth (Gautier
60). An imaging
radiometer has the capability to scan an area and provide pixels
of an area
giving more detailed images of the surface than a radiometer
(Gautier
60). A spectrometer detects, measures, and analyzes the
wavelengths of the
spectrum using prisms to separate the colors (Gautier 61).
Active instruments
provide electromagnetic radiation to observe an object
(Gautier 69). Satellites
that use active instruments send a pulse of energy
towards the object being
observed, then wait for the energy to be reflected
(Gautier 69). This energy is
then picked up as weaker or stronger in areas,
which can define what features
the satellite is looking at (Gautier 70). Some
active instruments are radar,
scatterometer, and lidar (Gautier 71). Radar
uses radio or microwaves to emit
electromagnetic radiation upon an object and
record the time between when the
energy leaves and comes back (Gautier71). A
scatterometer uses microwaves the
same way as radar, but it can measure wind
speed and direction (Gautier71).
Lidar uses lasers to transmit a light
source on the object being observed, they
can calculate a number of elements
in the atmosphere (Gautier 71). With all of
this scientists are able to
determine the heights of the oceans, able to predict
weather patterns and the
effects on the ocean. Future Unmanned space systems are
the most
cost-effective way to observe the planet (Victorov 109). The human
eye
however, has the best ability to observe the earth in a visual
perspective (Victorov
110). Humans in space play a valuable role in the
observation of oceans (Victorov
111). In the future people will be
permanently stationed in space stations to
observe and research the earth
(Victorov 111). How the satellites work
Satellites that observe the
surface of the earth rotate at the same speed as the
earth, this enables them
to take pictures from pole to pole (Victorov 123).
Figure 2 is a diagram
of a Geostationary Operational Environmental Satellite
(GOES). Figure 2(NASA)
A "GOES" satellite rotates above the earth at
22,000 miles. The camera on
the satellite sends photographs back to earth
through its antenna (Robinson
34). Solar panels use the sun to produce energy,
and the solar sail and trim
tab keep the satellite from spinning out of orbit
when the solar wind hits
the satellite (Robinson 34). Ocean color can indicate a
number of things to
an oceanographer, such as amount of plankton, and amount of
vegetation
(Gautier 117). The color of the ocean changes slightly, from a bright
blue to
a dark blue or black (Robinson 118). These changes in color happen
when
plankton float freely and concentrate in areas (Robinson 119).
These
concentrations are called blooms and are shown off the coast of Angola
in Figure
3. Figure 3 The ocean color can also turn into a blue-green
because of the
presence of large amounts of vegetation (Robinson 124).
Together, these colors
can indicate to scientists the productivity of the
oceans and potential for
greater amounts to wildlife (Robinson 125). Figure 4
is a false color image that
shows the amount of plankton in the ocean. Figure
4 The microscopic plankton are
the basis of the marine food web, without
plankton all marine life would suffer.
Thus, the importance of the
information from the false color images of plankton
on the earth becomes more
valuable. Conclusion Oceanography is a new science
that will unleash a lot of
new information to us on how planet earth works.
Oceanography from space
will be a tool for find out more about our oceans, but
there are limited
things it can do. It is expected that few major developments
in oceanography
will occur with satellites. The development of satellite
oceanography will
bring together ideas from all sciences to an overall
understanding about
oceans and earth as a whole.