1
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
E = Electric vector
M = Magnetic vector
C = Velocity of light
2
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Wavelength & Frequency
3
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Long wave length
Short wave length
Low frequency
Low energy
High frequency
High energy
Diagram of sine waves at different frequencies
4
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
If T increases, peak moves
towards shorter wavelengths,
and the total area under the
curve increases
3
T=
2
12
Wwatts/cm /m)
4
7
3
o
K=
10
0o
C
0
2
T=
107
1
3oK
=8
0
0oC
T=873oK=60 o
0C
T=673oK=400o
1.0
2.0
3.0
4.0
5.0
C
6.0
7.0
8.0
Wavelength, m
5
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Cosmic Gamma Xrays Rays
rays
Ultraviolet
U-V
0.40
Micro-waves TV
Green
0.50
Radio Electric power
Infrared
Visible spectrum
Blue
0.30
Infrared
Red
0.60
0.70
10.0
15.0
Wavelength (microns)
6
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Sun
Sun
R.S. Instrument
R.S. Instrument
Atmosperic absortion
Atmospheric absorption
Scattered
radiation
Scattered
radiation
Direct
Cloud
Cloud
radiation
Scattered
Earth
EARTH
7
Thermal
emission
Direct radiation
radiation
Scattered radiation
Reflected
radiation
Reflection processes
processes
Reflection
Dr. Tsehaie Woldai - Geological Survey Division
Atmospheric
emission
Atmospheric
emission
Thermal emission
Emission processes
Emission
processes
Electro Magnetic Energy and Remote Sensing
4
1.0 x 10
Solar extra terrestrial
6000K blackbody
0.8
Solar at earth’s surface
O3
O2
HHO
2O
O2
O
0.6
2
2
Visible
0.4
H 2O
HHO
2O
2
0.2
.4
.8
1.0
1.4
2
2
2
.2
HHO
2O
CO
Co2
HHO
2O
H2HO
O
1.8
2
2.0
2.4
2.6
2.8
3.0

Wavelength, m
Wavelength,
m
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Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
% transmission
100
H2O
and
CO2
50
O3
Co2
O3
CO2
0
2
4
2
HHO
2O
H 2O
6
CO2
8
10
12
14
16
18
20
22
Wavelength,
microns
Wavelength, microns
9
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Blue light
q1
Particle smaller than  blue
Red light
q2
Rayleigh principle (the shorter the wavelength, the greater the scattering)
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Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Rayleigh Scattering causes blue skies during daytime and red skies at sunset
Sun
B
Atmosphere
G
R
Blue sky
Earth
Day time
Sunset
Blue
Earth
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Dr. Tsehaie Woldai - Geological Survey Division
Sun
Red
Electro Magnetic Energy and Remote Sensing
B
Blue light
G
R
HO
2
= colloidal particles less than 1 micron
12
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
Non-Selective Scattering
13
Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
sensor
Zone of
no penetration
Cloud
Earth
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Dr. Tsehaie Woldai - Geological Survey Division
Cloud
Shadow
Electro Magnetic Energy and Remote Sensing
q
q
(a) Specular reflection from
a plane surface (ideal)
(b) Diffused reflection
from a rough surface
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Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
UV
UV
Visible
Light
NIR
Leaf
pigment
50
40
Emissive
thermal
infrared
Infrared
Reflective infrared
Cell
structure
MIR
Water content
Absorption for
photosynthesis
Factors
Contributing
leaf
reflectance
Absorption by free water
in plant tissue
30
20
10
0
0.1
0.4 0.5 0.6 0.7 0.8 0.9
1.1
1.35 1.4
1.9
Wavelengths (m)
3
5
Window
8
14
Window
An idealised spectral reflectance curve from a health vegetation.
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Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
a) Organic dominated
b) Minimally altered
c) Iron altered
d) Organic affected
e) Iron dominated
(from McCloy, 1995)
Reflectance spectra of surface samples of five mineral soils
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Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing
a) Ocean water
b) Turbid water
c) Water with chlorophyll
(from McCloy, 1995)
Typical effects of chlorophyll and sediments on water reflectance
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Dr. Tsehaie Woldai - Geological Survey Division
Electro Magnetic Energy and Remote Sensing