FIDUCEO: Advanced Very-High-Resolution Radiometer (AVHRR ) Climate Data Record for Aerosol Optical Depth, V1.0, 2003 -2012

The Fidelity and uncertainty in climate data records from Earth Observations (FIDUCEO) projcet Advanced Very-High-Resolution Radiometer (AVHRR ) Climate Data Record for Aerosol Optical Depth (AOD) dataset covers Europe and North Africa over land. It was inferred from AVHRR/3 instruments on board the NOAA-16 and NOAA-18 satellites. The dataset is provided on 3 processing levels: superpixels (L2B: 12x12 km2at nadir), gridded (1°x 1°) daily (L3 daily) and monthly (L3 monthly). The original lowest processing level (on selected dark field pixels) is not provided to users, but can be made available on request. The product contains the best AOD estimate but also a more detailed information on different aerosol types (most likely AOD value based on a multi-model ensemble climatology of the aerosol type and a 36 member ensemble of AOD values for a wide range of aerosol types spanning a realistic range in the atmosphere). A user can also process an application with all 36 ensemble members and then calculate the spread of the application results. Note that AOD values on the lowest processing level can be (slightly) negative reflecting radiometric calibration uncertaintiesand keeping un-cut AOD distributions. The products contain on all levels sophisticated and detailed estimates of total AOD uncertainties propagated from the input L1B products and the retrieval algorithm through all levels of the processing chain. These total uncertainties can be directly used for data assimilation or to constrain a confidence interval around the AOD solutions. AOD uncertainties are also kept separated into the (relevant) different parts with different correlation structures, so that a user can conduct averaging and uncertainty propagation as suitable for the intended applications. Uncertainties also include separate values for the dominant effects (reflectance inversion, albedo estimation, aerosol type, cloud masking); also estimates of a sampling uncertainty (due to missing pixels from the cloud masking or from failed inversions) are contained. More information including a report on the datset and scientific background is availible in the documentation section.