Monthly average, satellite-based Aerosol Optical Thickness derived from AEROSNOW

This dataset contains values for total aerosol optical depth (AOD) and was derived from reflectance measurements at the top of the atmosphere by the Advanced Along-Track Scanning Radiometer (AATSR) aboard ENVISAT over snow and ice in the Arctic, using a retrieval method known as AEROSNOW. AEROSNOW combines an existing aerosol retrieval algorithm with a cloud masking algorithm and a novel quality flagging method developed specifically for use in the high Arctic (Lat ≥ 72∘ N). We use the dual-viewing capability of the AATSR instrument to determine the contribution of aerosols to the reflection at the upper boundary of the atmosphere in observations *over the bright surfaces of the cryosphere* in the Arctic. AOD is determined under the assumption that the surface reflectance observed by the satellite can be well parameterized by a bidirectional snow reflectance distribution function. The dataset consists of a single file and contains AOD values from March through October of each year starting in 2003 and ending in 2011. AEROSNOW relies on solar irradiance and specific (geometric) observational conditions. Therefore, data for March and October are sparse, as the solar zenith angles are already too high at those times of year.