NOAA Climate Data Record (CDR) of AVHRR Daily and Monthly Aerosol Optical Thickness over Global Oceans, Version 2.0 (Version Superseded)

**Version 2 of the dataset has been superseded by a newer version. Users should not use version 2 except in rare cases (e.g., when reproducing previous studies that used version 2).**This NOAA Climate Data Record (CDR) of Aerosol Optical Thickness (AOT) is derived from data taken over global oceans from the PATMOS-x AVHRR level-2b channel 1 (0.63 micron) orbital clear-sky radiance. The retrieval is performed for selected spatial (8-km) and temporal (1 time per day) resolution in cloud free condition during daytime over global oceans. The AVHRR AOT CDR version 2 extends from 1981 to 2009 and includes both daily and monthly data in an equal angle grid (0.1x0.1 degree). Version 2 has improved cloud screening and data processing from version 1. Due to the relatively large uncertainties associated with surface reflectance over water glint area and land surface as well as limited AVHRR retrieval channels, the current algorithm only performs retrieval over non-glint water surface (specifically at the anti-solar side of the orbit and viewing angle is larger than 40 degree away from the specular ray).