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An overview of aerosol properties in clear and cloudy sky based on the CALIPSO observations
  • Yulan Hong,
  • Larry Di Girolamo
Yulan Hong
University of Illinois at Urbana Champaign

Corresponding Author:yulanh@illinois.edu

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Larry Di Girolamo
University of Illinois at Urbana Champaign
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A full understanding of the climatological properties of aerosols is an important step towards characterizing their effects on the regional and global climate. Utilizing the observations from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), we study cloud-free and cloudy aerosol properties with attentions on aerosol and cloud layer vertically relative positions. On a global scale, the cloud-free aerosols account for 55.9% of all detected aerosols with a mean optical depth ( ) and uncertainty of 0.135 {plus minus} 0.047. The cloudy aerosols, accounting for 44.1%, have a larger and uncertainty of 0.143 {plus minus} 0.074 compared to the cloud-free aerosols. The above-cloud aerosols (4.2%), primarily composed of elevated smoke, dust/volcanic ash and polluted dust, have a much smaller (0.056 0.038). The below-cloud aerosols (21.3%) have ~ 0.165 0.087, showing close probability density distributions, aerosol types, backscatter-depolarization ratio diagram, and lidar ratio-color ratio diagram with the cloud-free aerosols. In addition, 27.4% of the detected aerosol profiles are found to have cloud layers vertically connected to aerosol layers. The lidar backscatter profiles of these aerosols have larger median values than the cloud-free, above-cloud and below-cloud aerosols. The seasonal variability of the cloud-free and the cloudy aerosols significantly varies with regions. This study implies that quantifying the impact of clouds, particularly cirrus due to the wide coverage of cirrus-aerosol overlap, on aerosol direct radiative effect is crucial to assess aerosols’ roles in the Earth-climate system.
Apr 2022Published in Earth and Space Science volume 9 issue 4. 10.1029/2022EA002287