Atmospheric & Topographic Correction
for Small FOV Satellite Images
ATCOR 2 : Atmospheric Correction for Flat Terrain
ATCOR 3 : Atmospheric/Topographic Correction for Mountainous Terrain
Atmospheric and topographic correction, surface reflectance, emissivity, and temperature, satellite sensors, value adding products
The task of earth observing sensors is to map surface properties. However, the surface information is masked as the signal recorded by spaceborne optical sensors consists of several components and their magnitudes depend on atmospheric conditions, see Figure 1. In addition, topographic effects strongly influence the recorded signal. The objective of an atmospheric correction is to eliminate atmospheric and illumination effects to retrieve physical parameters of the earth's surface, e.g. surface reflectance, emissivity and temperature.
This information can be used for monitoring, change detection, surface-vegetation atmosphere transfer (SVAT) modeling, and surface energy balance investigations for climatic modeling and upscaling. Therefore, atmospheric correction is an essential part of preprocessing and a prerequisite for the derivation of certain value adding products.
The method is mainly intended for small field-of-view sensors where the angular dependence of atmospheric parameters can be neglected. However, some wide field-of-view sensors such as IRS-1C/1D WiFS are also supported.
As an additional option the following value adding products can be calculated: SAVI vegetation index, LAI, FPAR, albedo (wavelength-integrated reflectance 0.4-2.5 microns), and absorbed solar radiation flux. If the sensor has at least one thermal band and the boundary layer air temperature is specified then the following radiation and heat fluxes are included as additional output channels: difference between downwelling longwave thermal atmospheric flux and emitted surface flux, net radiation, ground heat flux, latent heat flux, sensible heat. All radiation and heat fluxes are given in Watts per square meter.
The ATCOR software was developed by DLR (German Aerospace Center) and is licensed to ReSe Applications Schläpfer for commercial marketing.