L11: Atmospheric Correction

Front 1

Why is atmospheric correction needed?

Back 1

When EM radiation enters the atmosphere, it is scattered, absorbed, or transmitted, causing interference with the image produced.

Front 2

Rayleigh Scattering

Back 2

Scattering by molecules: EM radiation scattering when the object doing the scattering is less than 1/10 the size of the wavelength being scattered

Front 3

Mie Scattering

Back 3

Scattering by aerosols: EM radiation scattering of particles whose size is the same or greater than the wavelength. Common cause include dust, pollen, and smoke. Occurs mostly in the lower portion of the atmosphere as larger particles are more abundant

Front 4

Optical Depth (Thickness)

Back 4

A measure of transparency. It is the total loss of intensity (attenuation) along a path. Generally a function of wavelength.

Front 5

Single Scattering Albedo

Back 5

Given an interaction between a photon and a particle, it is the probability that the photon as scattered in some direction, rather than being absorbed. A measure of the effectiveness of scattering relative to extinction of the light encountering atmospheric aerosol particles

Front 6

Scattering Phase Function

Back 6

Describes the angular distribution of light intensity scattered by a particle at a certain wavelength.
Probability per unit solid angle that a photon is scattered into a particular direction relative to the direction of the incident beam

Front 7

Absolute atmospheric correction

Back 7

Turns digital brightness values into reflectance values, which are then compared to other surface reflectance values obtained from other RS images

Front 8

Relative atmospheric correction

Back 8

This methods normalizes mutliple satellite scenes to each other, and usually involves the selection of ground targets whose reflectance values are considered constant, known as PIFs, and relating these targets to all imagery in the study

Front 9

Principles of aerosol correction using 5 RS signatures

Back 9

Multi spectral
Multi angular
Multi spatial
Multi temporal
Polarization method

Front 10

Multi spectral aerosol correction

Back 10

Instead of viewing bands in the typical order for the spectral extent that you want, you load different bands that are part of a spectral signature that is not affected by the atmosphere

Front 11

Multi angular aerosol correction

Back 11

Look at the same spatial extent through different viewing angles

Front 12

Multi spatial aerosol correction

Back 12

Histogram and cluster matching method

Front 13

Multi temporal aerosol correction

Back 13

Using images from other times, assuming that the surface properties have not changed significantly

Used for observing surface and atmosphere

Front 14

Polarization method of aerosol correction

Back 14

POLDER approach (Passive Optical Imaging Radiometer and Polarimeter)

Front 15

Band ratio algorithms

Back 15

Technique for estimating atmospheric water vapor content:
Continuum Interpolated Band Ratio
and
Curve fitting method (modified CIBR)

Front 16

Neural network algorithm

Back 16

Technique for estimating atmospheric water vapor content:
Extensive radiative transfer simulation using different atmospheric conditions and surface reflectance spectra