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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.

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Lesson 7 remote sensing

Lesson 7: Remote Sensing

Dr Andrew Ketsdever

MAE 5595


Outline
Outline

  • Electromagnetic Radiation

  • Blackbody Radiation

  • Atmospheric Windows

  • Instrument Parameters

  • Remote Sensing Architectures


Em radiation
EM Radiation

  • Photon wavelength, frequency and energy

h = 6.626 x 10-34 J sec


Em radiation1
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 radiation2
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
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

C1 = 3.74 x 10-16 Wm2 = 2phc2

C2 = 1.44 x 10-2 mK = hc/k


Blackbody radiation1
Blackbody Radiation

  • Wien’s Displacement Law

    • Defines wavelength in a blackbody at which the maximum energy is emitted


Blackbody radiation2
Blackbody Radiation

  • Stefan-Boltzmann Law

    • Relates the power emitted by a body to that body’s temperature

s = 5.669 x 10-8 Wm-2K-4


Other than blackbody radiation
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)





Atmospheric window
Atmospheric Window

M13 Observations

Rotational Transitions in CO


Window transmission
Window Transmission

Glass

Quartz

Sapphire


Instrument parameters
Instrument Parameters

Telescopes: Microwave, Radio, IR, Vis, UV, XRay, Gamma Ray


Instrument parameters1
Instrument Parameters

f – focal length

h – altitude

rd – radius of detector array

Rg – ½ Swath Width


Instrument parameters2
Instrument Parameters

  • Focal Length

Refractive System

Reflective System


Instrument parameters3
Instrument Parameters

  • F-Stop or F-Number

D - Aperture


Instrument parameters4
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 parameters5
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

h can be replaced by slant

range for off Nadir obs.


Instrument parameters6
Instrument Parameters

Aberration

Stigmatism

Coma




Instrument parameters9
Instrument Parameters

  • Silicon Imager Spectral Response


Instrument parameters10
Instrument Parameters

  • IR Detectors


Remote sensing architectures
Remote Sensing Architectures

Global Ocean Temperatures


Remote sensing architectures1
Remote Sensing Architectures

Passive

Active

Mie scattering (small particles)

Rayleigh Scattering (large particles)


Remote sensing architectures2
Remote Sensing Architectures

What is the driver for the remote sensing architecture?

Cosmic Background Explorer

SPOT

Mars Reconnaissance Orbiter


Remote sensing architectures3
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






Diffuse – Rough Surface

Specular – Smooth Surface

Maxwell Model



Remote sensing architectures8
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









Remote sensing architectures15
Remote Sensing Architectures

  • LIDAR

    • Light Detection and Ranging




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