Remote Sensing

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Remote Sensing Satellite Imagery
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Remote Sensing
REMOTE SENSING FOR ENVIRONMENTAL ISSUES  
Satellite and high altitude photography has
provided a means to survey the large water areas
of the planet for various disturbances and
pollution events. This is an efficient way to
monitor very large areas on a constant basis
many satellites make multiple passes per day over
given areas. Some progress around the earth's
surface covering even larger areas, but at less
frequent intervals. The positions of thousands of
these satellites is known with extraordinary
precision, and their paths can be predicted years
in advance. There are many different "kinds" of
satellites circling the globe. Some are
military, some civilian, some for communications
(TV, phone systems, data transmissions, etc.),
some for global positioning systems (GPS), some
for photography in visible and non-visible
wavelengths and some use radar wavelengths to
penetrate cloud cover.
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Detectors -imaging
Detectors Imaging Instruments An imaging
instrument uses optics such as lenses or mirrors
to project an image onto a detector, where it is
converted to digital data. Natural color imaging
requires taking three exposures of the same
target in quick succession through different
color filters, typically selected from a filter
wheel (typically Red, Green and Blue or RGB).
Earth-based processing combines data from the
three black and white images, reconstructing the
original color by utilizing the three values for
each picture element (pixel). Movies are
produced by taking a series of images over an
extended period of time. In the past, the
detector that created the image was a vacuum tube
resembling a small CRT (cathode-ray tube) Modern
spacecraft use CCDs, charge-coupled devices. A
CCD is usually a large-scale integrated circuit
having a two-dimensional array of hundreds of
thousands, or millions, of charge-isolated wells,
each representing a pixel in the image
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Detectors - other
Detectors Imaging Instruments An imaging
instrument uses optics such as lenses or mirrors
to project an image onto a detector, where it is
converted to digital data. Natural color imaging
requires taking three exposures of the same
target in quick succession through different
color filters, typically selected from a filter
wheel (typically Red, Green and Blue or RGB).
Earth-based processing combines data from the
three black and white images, reconstructing the
original color by utilizing the three values for
each picture element (pixel). Movies are
produced by taking a series of images over an
extended period of time. In the past, the
detector that created the image was a vacuum tube
resembling a small CRT (cathode-ray tube) Modern
spacecraft use CCDs, charge-coupled devices. A
CCD is usually a large-scale integrated circuit
having a two-dimensional array of hundreds of
thousands, or millions, of charge-isolated wells,
each representing a pixel in the image
Other Detectors Polarimeters are optical
instruments that measure the direction and extent
of the polarization of light reflected from their
targets. Careful analysis of polarimeter data can
infer information about the composition and
mechanical structure of the objects reflecting
the light, such as various chemicals and aerosols
in atmospheres, rings, and satellite surfaces,
since they reflect light with differing
polarizations. Photometers are optical
instruments that measure the intensity of light
from a source. They may be directed at targets
such as planets or their satellites to quantify
the intensity of the light they reflect, thus
measuring the object's reflectivity or albedo.
Also, photometers can observe a star while a
planet's rings or atmosphere intervene during
occultation, thus yielding data on the density
and structure of the rings or atmosphere.
Spectrometers are optical instruments that split
the light received from objects into their
component wavelengths by means of a diffraction
grating.
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Satellite Imaging


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Beijing
Beijing
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Death Valley
Death Valley
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Denver
Denver, Colorado 1999
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Downtown Denver
Downtown Denver, 1999
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Denver
Denver
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Florida Keys
The Florida Keys
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Grand Canyon
The Grand Canyon
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Jefferson Memorial
The Jefferson MemorialWashington, DC
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Mount Rainier
Mount Rainier, Washington State
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Santorini
Island of Santorini, Greece
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Bridges in Bangkok
Bridges in Bangkok
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Taipei
Taipei, Taiwan
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Hamilton
Skyway Bridge
Hamilton
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Toronto
Toronto
Leslie Street spit
Toronto Island Airport
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Welland
Welland Niagara
Niagara Falls
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Applications
Environmental Applications of Satellite Imagery
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Plankton Bloom
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East Coast chlorophyll
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Ocean
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Global Chlorophyll
Chlorophyll levels around the world varying with
season from composited satellite images
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Lake Ontario Ice
Ice on Lake Ontario
The RADARSAT satellite is a powerful microwave
instrument that can transmit and receive signals
to "see" through clouds, haze, smoke and
darkness. The satellite is able to obtain high
quality images of the Earth in any kind of
weather at any time. Using a single frequency, C-
Band, RADARSAT has the unique ability to shape
and steer its radar beam over a 500 km range.
Users have access to a variety of beam selections
that can image swath from 35 km to 500 km with
resolution of 10 meters to 100 meters,
respectively. RADARSAT is also the first
programmable radar satellite to offer a variety
of acquisition programming and delivery services.
Its on-board recorder means that it is now
possible to obtain a radar image anywhere in the
world and receive it in record time. Applications
of RADARSAT data include geology (mineral and
hydrocarbon exploration), cartography (especially
DTM production by radargrammetry) defence mapping
and surveillance, flood mapping, agriculture and
land use monitoring as well as a host of marine
applications such as oil spill detection, sea ice
monitoring for navigation, wave spectra analysis,
etc.
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Cape Verde Islands
Phytoplankton Bloom near Cape Verde Islands
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Baltic Sea
Phytoplankton blooms in the Baltic Sea
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Sulfur upwelling
Sulfur upwelling off the African coast, caused by
anaerobic bacterial growth
The anaerobic bacteria (bacteria that can live
without oxygen) feed upon dead algae that exist
in abundance on the oceans floor off of Namibia.
As the bacteria metabolize the algae, they
produce hydrogen sulfide, which slowly builds up
in the sea-floor sediments. Eventually, the
hydrogen sulfide reaches the point where the
sediment can no longer contain it, and it bubbles
forth. When this poisonous chemical reaches the
surface, it combines with the oxygen in the upper
layers of the ocean to create clouds of pure
sulfur. The sulfur causes the Namibian coast to
smell like rotten eggs, and the hydrogen sulfide
will often kill fish and drive lobsters away.
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Lake Michigan whiting
Dramatic change in the color of Lake Michigan
during the summer. The bright color that appears
in late summer is probably caused by calcium
carbonatechalkin the water. Lake Michigan
always has a lot of calcium carbonate in it
because the floor of the lake is limestone.
During most of the year the calcium carbonate
remains dissolved in the cold water, but at the
end of summer the lake warms up, lowering the
solubility of calcium carbonate. As a result, the
calcium carbonate precipitates out of the water,
forming clouds of very small solid particles that
appear as bright swirls from above. The
phenomenon is appropriately called a whiting
event. A similar event occurred in 1999,but
appears to have started later and subsided
earlier.
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Black Sea
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Sea of Azoz
These SeaWiFS satellite images provide good views
of the eutrophic and turbid (below) Sea of
Azov. The larger body of water to the south is
the Black Sea
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Global Carbon Monoxide
Carbon monoxide is a gaseous byproduct from the
burning of fossil fuels, in industry and
automobiles, as well as burning of forests and
grasslands. Notice in the April 30, 2000, image
that levels of carbon monoxide are much higher in
the Northern Hemisphere, where human population
and human industry is much greater than in the
Southern Hemisphere. However, in the October 30,
2000, image notice the immense plumes of the gas
emitted from forest and grassland fires burning
in South America and Southern Africa. The
instrument was developed by Canadian scientists
at the University of Toronto and built by COM DEV
International of Cambridge, Ontario
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Chilean mine
The Escondida copper, gold, and silver open-pit
mine in the Atacama Desert, Chile is at an
elevation of 3050 m, and came on stream in 1990.
Current capacity is 127,000 tons/day of ore in
1999 production totaled 827,000 tons of copper,
150,000 ounces of gold and 3.53 million ounces of
silver. Primary concentration of the ore is done
on-site the concentrate is then sent to the
coast for further processing through a 170 km
long, 9" pipe. Escondida is related geologically
to three porphyry bodies intruded along the
Chilean West Fissure Fault System. A high grade
supergene cap overlies primary sulfide ore. The
top image is a conventional 3-2-1 (near infrared,
red, green) RGB composite. The bottom image
displays shortwave infrared bands 4-6-8 (1.65µm,
2.205µm, 2.33µm) in RGB, and highlights the
different rock types present on the surface, as
well as the changes caused by mining.
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Arabian Sea Oil slicks
This is a radar image of an offshore drilling
field about 150 km (93 miles) west of Bombay,
India, in the Arabian Sea. The dark streaks are
extensive oil slicks surrounding many of the
drilling platforms, which appear as bright white
spots. Radar images are useful for detecting
and measuring the extent of oil seepages on the
ocean surface, from both natural and industrial
sources. The long, thin streaks extending from
many of the platforms are spreading across the
sea surface, pushed by local winds. The larger
dark patches are dispersed slicks that were
likely discharged earlier than the longer
streaks, when the winds were probably from a
different direction. The dispersed oil will
eventually spread out over the more dense water
and become a layer which is a single molecule
thick. Many forms of oil, both from biological
and from petroleum sources, smooth out the ocean
surface, causing the area to appear dark in radar
images. There are also two forms of ocean waves
shown in this image. The dominant group of large
waves (upper center) are called internal waves.
These waves are formed below the ocean surface at
the boundary between layers of warm and cold
water and they appear in the radar image because
of the way they change the ocean surface. Ocean
swells, which are waves generated by winds, are
shown throughout the image but are most distinct
in the blue area adjacent to the internal waves.
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Aral Sea
Aral Sea
The Aral Sea is actually not a sea at all. It is
an immense lake, a body of fresh water. In the
last 30 years, more than 60 percent of the lake
has disappeared. The sequence of images, acquired
by Landsat satellites, shows the dramatic changes
to the Aral Sea between 1973 and 2000. Beginning
in the 1960s, farmers and state offices in
Uzbekistan, Kazakhstan, and Central Asian states
opened significant diversions from the rivers
that supply water to the lake, thus siphoning off
millions of gallons to irrigate cotton fields and
rice paddies. As recently as 1965, the Aral Sea
received about 50 cubic kilometers of fresh water
per year--a number that fell to zero by the early
1980s. Consequently, concentrations of salts and
minerals began to rise in the shrinking body of
water. That change in chemistry has led to
staggering alterations in the lake's ecology,
causing precipitous drops in the Aral Sea's fish
population. The Aral Sea supported a thriving
commercial fishing industry employing roughly
60,000 people in the early 1960s. By 1977, the
fish harvest was reduced by 75 percent, and by
the early 1980s the commercial fishing industry
had been eliminated. The shrinking Aral Sea has
also had a noticeable affect on the region's
climate. The growing season there is now shorter,
causing many farmers to switch from cotton to
rice, which demands even more diverted water.
1973
1987
2000
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2006
1989
1977
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Washington Impervious surface
The image shows the extent of impervious surfaces
in and around Washington and Baltimore. Red
represents high concentrations of impervious
surfaces. Blue represents moderate concentrations
and green represents low concentrations of
impervious surfaces
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Watershed Cote DArmor
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DEMs
A DEM is a gridded digital elevation file of an
area. Typical grid spacing is one elevation value
every 20 metres. The DEM is generated by
automatically correlating two SPOT (or other
satellite images. The DEM is used to produce
orthoimages and contour files.
3D perspective of Northeast Iraq, similar to the
views pilots used to plan and rehearse their
flights during Desert Storm The U.S. Department
of Defense used Spot imagery in conjunction with
a computerized mission planning system to plan
sorties with entry and escape routes. Spot
satellites supplied 220 panchromatic images which
were combined with Defense Mapping Agency digital
elevation data. Pilots could then view a
realistic 3-D landscape as well as detailed
terrain and cultural features
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West Nile Virus
This image is a composite of land surface
temperatures (LST) recorded between 1997 and 2000
and was used to help monitor and predict the
spread of West Nile virus in the United States.
Mean land surface temperatures are in red
annual amplitudeor the difference between low
and high annual temperaturesis in blue and
annual phaseor the timing of annual temperature
peaksappears in green. Brighter colors mean
higher values. The major north-south temperature
difference (dull red in the upper part of the
image to bright red in the lower part) is
considerably affected by the Rockies in the west
and to a much lesser extent by the Appalachians
in the east. The brighter blue in the upper part
of the image indicates the big difference between
highest and lowest temperatures during the course
of a year at higher latitudes. There is less
variation in the timing of the annual peak of
land surface temperatures, which occurs earlier
in the south than in the north. Black dots
superimposed on this image are the locations
(county geo-centers) where birds infected with
West Nile virus were reported between January and
October 2001.
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Land Cover
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Land Cover with key
Colour coded key
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Mozambique Pre-flood
The Mozambique Coast in August 1999 before
flooding Landsat 7 Satellite
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Mozambique flood
The Mozambique Coast in March 2000 after rains
and flooding Landsat 7 Satellite
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Hawaii Land Use
HawaiiThis map will be used as a baseline to
chart changes in land use on the islands. Types
of change include the construction of resorts
along the coastal areas, and the conversion of
sugar plantations to other crop types The black
areas on the island are hardened lava flows
formed by the active Mauna Loa Volcano. Just to
the north of Mauna Loa is the dormant grayish
Mauna Kea Volcano. A thin greyish plume of smoke
is visible near the islands southeastern shore,
rising from Kilaueathe most active volcano on
Earth. Hawaiis tropical forests appear as solid
dark green areas in the image. The light green,
patchy areas near the coasts are sugar cane
plantations, pineapple farms, and human
settlements.
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End
End
Colin Mayfield 2002