New parametric approach to decomposition of disk averaged spectra of potential extra terrestrial planet I. Surface type ratio of the Earth

We built 7 potential extra-terrestrial planets including the full 3D Earth model with various surface types and 6 planet models, each with uniform surface characteristics. The surface types include ice, tundra, forest, grass, ground and ocean. We then imported these 7 planets into integrated ray tracing(IRT) model to compute their disk averaged spectra and to understand the spectral behavior depending on the geometrical view, illumination phase and seasonal change. The IRT computation show that the 6 planets with uniform surfaces exhibit clear spectral differences from that of the Earth. We then built a phase and seasonal DAS database for the 6 uniform surface planets and used them for parametric spectral decomposition technique to derive the Earth DAS. This computation resulted in the first potential solution to the surface type ratio of the Earth compared to the measured earth surface type ratio. The computational details and the implications are discussed.