Environmental Engineering Reference
In-Depth Information
Knowing the exact location of a pixel on the
Earth
detect pollutants in the upper levels of the ocean
and to determine the nature of materials suspended
in the water column. The Nimbus satellite was
placed in a sun-synchronous, near-polar orbit at an
altitude of 955 km. Equator crossing times were
local noon for ascending passes and local midnight
for descending passes.
The repeat cycle of the satellite allowed for
global coverage every 6 days or every 83 orbits.
The CZCS sensor consisted of six spectral bands
in the visible, near-IR and thermal portions of the
spectrum each collecting data at a spatial reso-
lution of 825 m at nadir over a 1,566-km swath
width.
The
s surface (its spatial location) is an essen-
tial component of remote sensing. It requires a
detailed knowledge of the size and the shape of
the Earth.
The Earth is not a simple sphere. Topographic
features such as mountain ranges and deep
oceans disturb the surface of the Earth. The ideal
reference model for the Earth
'
s shape is one that
can represent these irregularities and identify the
position of features through a coordinate system.
It should also be easy to use.
The
'
model is not appropriate when
mapping larger areas. It does not take into
account the curvature of the Earth. A
' fl
at Earth
'
'
curved
rst Marine Observation Satellite (MOS-1)
was launched by Japan in February 1987 and was
followed by its successor, MOS-1b, in February of
1990. These satellites carry three different sensors:
a four-channel Multispectral Electronic Self-
Scanning Radiometer (MESSR
Earth
model more closely represents the shape
of the Earth. A spheroid best represents the shape
of the Earth because it is signi
'
cantly wider at
the equator than around the poles (unlike a
simple sphere). A spheroid (also known as an
ellipsoid) represents the equator as an elliptical
shape, rather than a round circle. Surveying and
navigation calculations can be performed over a
large area when a spheroid is used as a curved
Earth reference model.
The surface of the sea is not uniform. The
Earth
50 m resolu-
tion), a four-channel Visible and Thermal Infrared
Radiometer (VTIR
900 to 2,700 m resolution)
and a two-channel Microwave Scanning Radi-
ometer (MSR), in the microwave portion of the
spectrum. The MESSR bands are quite similar in
spectral range to the Landsat MSS sensor and are
thus useful for land applications in addition to
observations of marine environments. The MOS
systems orbit at altitudes around 900 km and have
revisit periods of 17 days.
The SeaWiFS (sea-viewing wide
'
s gravitational
eld shapes it. The rocks
that make up the Earth
s interior vary in density
and distribution, causing anomalies in the grav-
itational
'
eld. These, in turn, cause irregularities
in the sea surface. A mathematical model of the
sea surface can be formulated; however,
eld of view
sensor) on-board SeaStar spacecraft is an
advanced sensor designed for ocean monitoring.
It consists of eight spectral bands of very narrow
wavelength ranges (see accompanying table)
tailored for very speci
it
is
very complex and not useful
nding
geographic positions on a spheroid reference
model.
for
c detection and monitor-
ing of various ocean phenomena including ocean
primary production and phytoplankton processes,
ocean in
3.1.8 Satellite/Sensor: Exclusive
for Monitoring Marine
Ecosystem and Blue Carbon
uences on climate processes (heat
storage and aerosol formation) and monitoring of
the cycles of carbon, sulphur and nitrogen. The
orbit altitude is 705 km with a local equatorial
crossing time of 12 noon. Two combinations of
spatial resolution and swath width are available
for each band: a higher resolution mode of
1.1 km (at nadir) over a swath of 2,800 km and a
lower resolution mode of 4.5 km (at nadir) over a
swath of 1,500 km.
fl
The Nimbus-7 satellite, launched in 1978, carried
the
rst sensor, the Coastal Zone Colour Scanner
(CZCS), speci
cally intended for monitoring the
Earth ' s oceans and water bodies. The primary
objective of this sensor was to observe ocean col-
our and temperature, particularly in coastal zones,
with suf
cient spatial and spectral resolution to
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