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Title: Satellite retrieval of cloud condensation nuclei concentrations by using clouds as CCN chambers

Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities ( Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. In this paper, our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation ( S) is determined by Wb and the satellite-retrieved cloud base drop concentrations ( Ndb), which is the same as CCN(S). Validation against ground-based CCN instruments at Oklahoma, at Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. Finally, the limitation for small solar backscattering angles of <25° restricts the satellite coverage to ~25% of the world area in a single day.
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [3] ;  [5] ;  [6] ;  [5] ;  [5] ;  [1] ;  [2] ;  [1] ;  [1] ;  [7] ; ORCiD logo [7] ;  [3] ; ORCiD logo [3]
  1. The Hebrew Univ. of Jerusalem, Jerusalem (Israel)
  2. Univ. of Maryland, College Park, MD (United States); Beijing Normal Univ., Beijing (China)
  3. Max Planck Institute for Chemistry, Mainz (Germany)
  4. National Oceanic and Atmospheric Administration, Boulder, CO (United States)
  5. Meteorological Institute of Shaanxi Province, Xi'an (China)
  6. Beijing Normal Univ., Beijing (China); Meteorological Institute of Shaanxi Province, Xi'an (China)
  7. Univ. of Sao Paulo, Sao Paulo (Brazil)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 21; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Hebrew Univ. of Jerusalem (Israel)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; CCN concentrations; satellite remote sensing; convective clouds; cloud−aerosol interactions
OSTI Identifier: