Preprints
https://doi.org/10.5194/acp-2021-1
https://doi.org/10.5194/acp-2021-1

  17 Feb 2021

17 Feb 2021

Review status: this preprint is currently under review for the journal ACP.

Global Dust Optical Depth Climatology Derived from CALIOP and MODIS Aerosol Retrievals on Decadal Time Scales: Regional and Interannual Variability

Qianqian Song1,2, Zhibo Zhang1,2, Hongbin Yu3, Paul Ginoux4, and Jerry Shen3, Qianqian Song et al.
  • 1Physics Department, UMBC, Baltimore, Maryland, USA
  • 2Joint Center of Earth Systems Technology, UMBC, Baltimore, Maryland, USA
  • 3Earth Sciences Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 4NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA
  • A summer intern worked at NASA Goddard Space Flight Center during June–August 2020.

Abstract. We present a satellite-derived global dust climatological record over the last two decades, including the monthly mean visible dust optical depth (DAOD) and vertical distribution of dust extinction coefficient at a 2º (latitude) × 5º (longitude) spatial resolution derived from CALIOP and MODIS. Dust is distinguished from non-dust aerosols based on particle shape information (e.g., lidar depolarization ratio) for CALIOP, and on dust size and absorption information (e.g., fine-mode fraction, Angstrom exponent, and single-scattering albedo) for MODIS, respectively. On multi-year average basis, the global (60° S–60° N) and annual mean DAOD is 0.029 and 0.063 derived from CALIOP and MODIS retrievals, respectively. In most dust active regions, CALIOP DAOD generally correlates well with the MODIS DAOD, with CALIOP DAOD being significantly smaller. CALIOP DAOD is 18 %, 34 %, 54 % and 31 % smaller than MODIS DAOD over Sahara Deserts, the tropical Atlantic Ocean, the Caribbean Sea, and the Arabian Sea, respectively. Over East Asia and the northwestern Pacific Ocean (NWP), however, the two datasets show weak correlation. Despite these discrepancies, CALIOP and MODIS show similar seasonal and interannual variations in regional DAOD. For dust aerosol over NWP, both CALIOP and MODIS show a declining trend of DAOD at a rate of about 2 % yr−1. This decreasing trend is consistent with the observed declining trend of DAOD in the southern Gobi Desert at a rate of −3 % yr−1 and −5 % yr−1 according to CALIOP and MODIS, respectively. The decreasing trend of DAOD in the southern Gobi Desert is in turn found to be significantly correlated with an increasing trend of vegetation and a decreasing trend of surface wind speed in the area.

Qianqian Song et al.

Status: open (until 14 Apr 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Qianqian Song et al.

Qianqian Song et al.

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