Aerosol properties from OMI using the multi-wavelength algorithm

The multi-wavelength retrieval algorithm is used to retrieve aerosol parameters from spectra reflectance measurements of the Ozone Monitoring Instrument (OMI). This retrieval algorithm uses up to 19 wavelength bands between 331 nm and 500 nm including a band at 477 nm comprising an absorption band of O₂-O₂. This absorption band has been included in order to increase the amount of height information that can be extracted from the measurement. A principal component analysis shows that OMI measurements have 2 to 4 degrees of freedom of signal, which for cloud free scenes can be attributed to aerosol parameters. In the multi-wavelength algorithm the aerosol optical thickness at a reference wavelength is retrieved for a set of aerosol models and the best fitting aerosol model is determined. The aerosol models are determined by the single-scattering albedo, the layer height, and the size distribution. The algorithm is capable to distinguish between absorbing aerosol types, such as desert dust and biomass burning, and weakly absorbing aerosols like sea-salt and sulfates. We show retrieved aerosol parameters for various scenes and conditions. Furthermore we show how height information from space borne lidar instruments (e.g. CALIPSO) can be used in the OMI retrievals.