Lesson 7: Remote Sensing
Dr Andrew Ketsdever
MAE 5595
Outline
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Electromagnetic Radiation
Blackbody Radiation
Atmospheric Windows
Instrument Parameters
Remote Sensing Architectures
EM Radiation
• Photon wavelength,
frequency and energy
c  
E  h
h = 6.626 x 10-34 J sec
EM Radiation
• Communications
• Microwaves: 1 mm to 1 m wavelength. The
microwaves are further divided into different
frequency (wavelength) bands: (1 GHz = 109 Hz)
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P band: 0.3 - 1 GHz (30 - 100 cm)
L band: 1 - 2 GHz (15 - 30 cm)
S band: 2 - 4 GHz (7.5 - 15 cm)
C band: 4 - 8 GHz (3.8 - 7.5 cm)
X band: 8 - 12.5 GHz (2.4 - 3.8 cm)
Ku band: 12.5 - 18 GHz (1.7 - 2.4 cm)
K band: 18 - 26.5 GHz (1.1 - 1.7 cm)
Ka band: 26.5 - 40 GHz (0.75 - 1.1 cm)
V band: 50 – 75 GHz
W band: 75 – 111 GHz
EM Radiation
• Heat energy is the KE of random motion of
the particles in matter
• Temperature is the measure of heat
energy concentrated in a substance
• Random motion results in COLLISIONS
• COLLISIONS cause changes in the
internal energy of the molecules
• Internal energy modes relax to ground
state by giving off photons (EM Radiation)
Blackbody Radiation
• An ideal thermal emitter
– Transforms heat energy
into radiant energy at the
maximum rate allowed
(Thermodynamics)
– Any real material at the
same temperature can
not emit at a rate in
excess of a blackbody
• An ideal thermal
absorber
• Planck’s formula

M   c1 e

5
c2
T

 1

1
C1 = 3.74 x 10-16 Wm2 = 2phc2
C2 = 1.44 x 10-2 mK = hc/k
Blackbody Radiation
• Wien’s
Displacement
Law
– Defines
wavelength in a
blackbody at
which the
maximum energy
is emitted
3
2.898 x10 mK
m 
T
Blackbody Radiation
• Stefan-Boltzmann Law
– Relates the power emitted
by a body to that body’s
temperature

q   T T
4
sfc
4
amb

 = 5.669 x 10-8 Wm-2K-4
Other Than Blackbody Radiation
• Emissivity
– Ratio of the spectral
energy radiated by a
material to that of a
blackbody at the same
temperature
– Can depend on
• Wavelength
• Temperature
• Phase (solid/liquid)

q   T  T
4
sfc
4
amb

Atmospheric Windows
Atmospheric Windows
Atmospheric Windows
Atmospheric Window
M13 Observations
Rotational Transitions in CO
Window Transmission
Glass
Quartz
Sapphire
Instrument Parameters
Telescopes: Microwave, Radio, IR, Vis, UV, XRay, Gamma Ray
Instrument
Parameters
rd
f

 Magnificat ion
h Rg
f – focal length
h – altitude
rd – radius of detector array
Rg – ½ Swath Width
Instrument Parameters
• Focal Length
Refractive System
Reflective System
Instrument Parameters
• F-Stop or F-Number
f
F#
D
D - Aperture
Instrument Parameters
• A telescope's spatial (or angular)
resolution refers to how well it can
distinguish between two objects in
space which are separated by a small
angular distance.
• The closer two objects can be while
still seen as two separate objects, the
higher the spatial resolution of the
telescope.
• The spatial resolution of a telescope
affects how well details can be seen
in an image.
– A telescope with higher spatial resolution
creates clearer and more detailed
images.
Instrument Parameters
• Diffraction Limited
Resolution
– Rayleigh diffraction
criteria
– Angular distance from
maximum brightness
at the center of the
image to the first dark
interference ring
 r  1.22

D
X   2h r  2.44
h
D
h can be replaced by slant
range for off Nadir obs.
Instrument Parameters
Aberration
Stigmatism
Coma
Instrument Parameters
Instrument Parameters
Instrument Parameters
• Silicon Imager Spectral Response
Instrument Parameters
• IR Detectors
Remote Sensing Architectures
Global Ocean
Temperatures
Remote Sensing Architectures
Passive
Active
Mie scattering (small particles)
Rayleigh Scattering (large particles)
Remote Sensing Architectures
What is the driver for the
remote sensing architecture?
Cosmic Background Explorer
SPOT
Mars Reconnaissance Orbiter
Remote Sensing Architectures
Landsat 7
•a panchromatic band with 15m spatial resolution
•on-board, full aperture, 5% absolute radiometric calibration
•a thermal IR channel with 60m spatial resolution
•an on-board data recorder
Remote Sensing Architectures
Baghdad
Chicago
Remote Sensing Architectures
Remote Sensing Architecture
Remote Sensing Architectures
Diffuse – Rough Surface
Specular – Smooth Surface
Maxwell Model
Remote Sensing Architectures
Remote Sensing Architectures
• Space Radar
– Mauna Loa Volcano
• Rift Zones (Orange)
• Smooth Lava Flows (Red)
– Pahoehoe Flows
• Rough Lava Flows
(Yellow/White)
– A’a Flows
– Obtained by sensing
different Radar bands
Space Radar Systems
Remote Sensing Architectures
Remote Sensing Architectures
Remote Sensing Architectures
Remote Sensing Architectures
Remote Sensing Architectures
Remote Sensing Architectures
Remote Sensing Architectures
• LIDAR
– Light Detection and Ranging
Remote Sensing Architectures
Remote Sensing Architectures
• Pushbroom Sensor