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Lesson 7: Remote Sensing. Dr Andrew Ketsdever MAE 5595. Outline. Electromagnetic Radiation Blackbody Radiation Atmospheric Windows Instrument Parameters Remote Sensing Architectures. EM Radiation. Photon wavelength, frequency and energy. h = 6.626 x 10 -34 J sec. EM Radiation. - PowerPoint PPT Presentation
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Lesson 7: Remote Sensing
Dr Andrew Ketsdever
MAE 5595
Outline
• Electromagnetic Radiation
• Blackbody Radiation
• Atmospheric Windows
• Instrument Parameters
• Remote Sensing Architectures
EM Radiation
• Photon wavelength, frequency and energy c
hE 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) – 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 formula1
51 1
2
T
c
ecM C1 = 3.74 x 10-16 Wm2 = 2hc2
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
T
mKxm
310898.2
Blackbody Radiation
• Stefan-Boltzmann Law– Relates the power emitted
by a body to that body’s temperature
44ambsfc TTq
= 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)
44ambsfc TTq
Atmospheric Windows
Atmospheric Windows
Atmospheric Windows
Atmospheric WindowM13 ObservationsRotational Transitions in CO
Window Transmission
Glass Quartz
Sapphire
Instrument ParametersTelescopes: Microwave, Radio, IR, Vis, UV, XRay, Gamma Ray
Instrument Parameters
ionMagnificatR
r
h
f
g
d
f – focal lengthh – altituderd – radius of detector arrayRg – ½ Swath Width
Instrument Parameters
• Focal Length
Refractive System Reflective System
Instrument Parameters
• F-Stop or F-Number
D
fF #
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 Dr
22.1
D
hhX r
44.22
h can be replaced by slantrange for off Nadir obs.
Instrument Parameters
Aberration
Coma
Stigmatism
Instrument Parameters
Instrument Parameters
Instrument Parameters
• Silicon Imager Spectral Response
Instrument Parameters
• IR Detectors
Remote Sensing Architectures
Global Ocean Temperatures
Remote Sensing Architectures
Mie scattering (small particles)Rayleigh Scattering (large particles)
PassiveActive
Remote Sensing Architectures
Cosmic Background Explorer
SPOT Mars Reconnaissance Orbiter
What is the driver for the remote sensing architecture?
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
Chicago
Baghdad
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
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