Mathematical Simulation of Satellite Measurements to Develop Spectroscopic Methods of CO2 Determination in the Presence of Thin or Broken Clouds

Using mathematical modeling of measurements of SCIAMACHY/ENVISAT spectrometer, the method of CO₂ concentration determination under conditions of the semi-transparent and broken clouds has been developed. The method is based on simultaneous measurements of solar spectral reflectivities of the "underlying surface+atmosphere" system within absorption bands of oxygen (near 760 nm) and carbon dioxide (near 1600 nm) for channel pairs specifically selected within each band. The criterion for their selection is the equality of change ranges of relative optical thickness or their linear combinations by transition from clear sky conditions to cloud cover ones. Such approach allows to reach the accuracy of CO₂ concentration measurements of approximately 1÷2% for a broad set of cloudy scenes.