Molecular Line Absorption in a Scattering Atmosphere. Part II: Application to Remote Sensing in the O₂A band

This paper explores the feasibility of using O 2 A-band reflectance spectra in the retrieval of cloud optical and physical properties. Analyses demonstrate that these reflection spectra are sensitive to optical properties of clouds such as optical depth c and phase function, vertical profile information including cloud-top pressure, pressure thickness, and the surface albedo. An estimation method is developed to demonstrate how well this information might be retrieved from synthetic spectra calculated by a line-by-line spectral multiple scattering model assuming realistic instrument parameters (spectral resolution, calibration accuracy, and signal-to-noise properties). The quality of the retrievals is expressed in terms of two indices, one relating to total error and another that quantifies the extent of reliance of the retrieval on the measurement, or conversely on other a priori information. Sources of total error include instrument-related errors, forward model errors including phase function errors, and errors in a priori data.