McCART: Monte Carlo Code for Atmospheric Radiative Transfer

McCART is a numerical procedure to solve the radiative transfer equation for light propagation through the atmosphere from visible to near-infrared wavelengths. The procedure has been developed to study the effect of the atmosphere in the remote sensing of the Earth, using aerospace imaging spectrometers. The simulation is run for a reference layered plane nonabsorbing atmosphere and a plane ground with uniform reflectance. For a given distribution of ground reflectance and for a specific profile of scattering and absorption properties of the atmosphere, the spectral response of the sensor is obtained in a short time from the results of the Monte Carlo simulation by using scaling relationships and symmetry properties. The procedure also includes an accurate analysis of the adjacency and trapping effects due to multiple scattering of photons coming from neighboring pixels. McCART can generate synthetic images of the Earth’s surface for arbitrary viewing conditions. The results can be used to establish the limits of applicability of approximate algorithms for the processing and analysis of hyperspectral images acquired by imaging spectrometers. In addition, the algorithm can be used to develop procedures for atmospheric correction for the accurate retrieval of the spectral ground reflectance.