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 = x J sec

EM Radiation Communications Microwaves: 1 mm to 1 m wavelength. The microwaves are further divided into different frequency (wavelength) bands: (1 GHz = 10 9 Hz) –P band: GHz ( cm) –L band: GHz ( cm) –S band: GHz ( cm) –C band: GHz ( cm) –X band: GHz ( cm) –Ku band: GHz ( cm) –K band: GHz ( cm) –Ka band: GHz ( 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 C 1 = 3.74 x Wm 2 = 2  hc 2 C 2 = 1.44 x mK = hc/k

Blackbody Radiation Wien’s Displacement Law –Defines wavelength in a blackbody at which the maximum energy is emitted

Blackbody Radiation Stefan-Boltzmann Law –Relates the power emitted by a body to that body’s temperature  = x Wm -2 K -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)

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 f – focal length h – altitude r d – radius of detector array R g – ½ Swath Width

Instrument Parameters Focal Length Refractive SystemReflective System

Instrument Parameters F-Stop or F-Number 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 h can be replaced by slant range for off Nadir obs.

Instrument Parameters Aberration Coma Stigmatism

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) Passive Active

Remote Sensing Architectures Cosmic Background Explorer SPOTMars 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

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

LIDAR –Light Detection and Ranging

Remote Sensing Architectures

Pushbroom Sensor