Aerosol Retrieval from OMI: Validation Results

Aerosols have direct impact on climate change, by scattering the incoming solar radiation. This effect is relatively well understood (Haywood and Boucher, 2000). Aerosols can also affect the climate indirectly when the hygroscopic particles act as cloud condensation nuclei (CCN) and influence the physical and chemical cloud properties. Therefore, it is of primary importance to monitor aerosols. Satellite observations provide information on aerosol properties over a larger area and can be used for monitoring on regional and global scales. The primary parameter is the aerosol optical depth (AOD) which provides information on the total concentration of particles and its spectral variation gives indications on the shape of the size distribution. The accuracy of the retrieval of the aerosol optical depth (Veefkind et al, 2000, Robles Gonzales, 2003) in clear sky condition over both dark and bright surfaces indicates that, nowadays, satellite based instrument are the best choice to retrieve aerosol properties on regional or larger scale. In this study, the ozone monitoring instrument is used to retrieve the AOD over north Western Europe for May to July 2005. The Ozone Monitoring Instrument (OMI) is a Dutch-Finish contribution to the AURA mission. OMI is a nadir viewing spectrometer; it measures solar reflected and backscattered light in a part of the UV-Visible domain (270-500 nm). The near UV part of the spectrum observed by OMI enables the detection of absorbing aerosols such as dust and biomass burning. To derive aerosol optical properties from the reflectance at the top of the atmosphere measured by OMI, a new multi-wavelength method was developed. The main goal of this study is to validate the consistency of the OMI aerosol product derived by means of this algorithm