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[1] Intensive research on the distribution of aerosols is being conducted within many international research programs (e.g., Global Energy and Water Cycle Experiment and International Global Atmospheric Chemistry Experiment). Obviously, satellite remote sensing allows for global monitoring; however, operational satellite observation has for a long time been limited to either the oceans or to UV-absorbing aerosols. Therefore a new aerosol retrieval method, Synergetic Aerosol Retrieval (SYNAER), to derive aerosol optical depth and type, both over land and over ocean, was developed (see part 1 of this paper, Holzer-Popp et al. [2002]). First, case studies showing its application and a validation using ground-based and airborne measurements are presented. They show a good agreement with better than 0.1 in boundary layer aerosol optical thickness at 550 nm and indicate a detection of the correct aerosol type in most cases. Restrictions for the detection of aerosol type appear over bright surfaces and in areas with an aerosol optical depth less than 0.1 due to a low aerosol sensitivity in these situations. The method has been developed for the future operational use of similar sensor pairs Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY)/Advanced Along Track Scanning Radiometer (AATSR) and Global Ozone Monitoring Experiment 2 (GOME-2)/Advanced Very High Resolution Radiometer (AVHRR). Thus SYNAER holds the potential to extract a 25-year-long climatological data set (1995–2020) from ERS-2, Envisat, and METOP.

[1] A new aerosol retrieval method called Synergetic Aerosol Retrieval (SYNAER), using simultaneous measurements of the radiometer Along Track Scanning Radiometer (ATSR-2) and the spectrometer Global Ozone Monitoring Experiment (GOME) in the visible and near-infrared spectra, was developed. Both instruments are flown onboard the European Remote Sensing (ERS-2) satellite. SYNAER delivers boundary layer aerosol optical thickness (BLAOT) and aerosol type both over land and over ocean, the latter as BLAOT percentage of six representative components from the Optical Parameters of Aerosols and Clouds (OPAC) data set. The high spatial resolution of ATSR-2 permits accurate cloud detection. It allows BLAOT calculation over automatically selected dark pixels and surface albedo correction for a set of boundary layer aerosol mixtures. After spatial integration and colocation to GOME pixels, these parameters are used to simulate GOME spectra for the same set of aerosol mixtures. A least squares fit of these spectra to the measured and cloud-corrected GOME spectrum chooses the aerosol mixture. First validation studies are presented in part 2 of this paper [Holzer-Popp et al., 2002]. The method will be used for the future sensor pairs Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY)/Advanced ATSR (AATSR) on Envisat and GOME-2/Advanced Very High Resolution Radiometer (AVHRR) on METOP. Thus, SYNAER holds the potential to extract a long-term climatological data set.