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

Daniel Rosenfeld*, Youtong Zheng, Eyal Hashimshoni, Mira L. Pöhlker, Anne Jefferson, Christopher Pöhlker, Xing Yu, Yannian Zhu, Guihua Liu, Zhiguo Yue, Baruch Fischman, Zhanqing Li, David Giguzin, Tom Goren, Paulo Artaxo, Henrique M.J. Barbosa, Ulrich Pöschl, Meinrat O. Andreae

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

102 Scopus citations

Abstract

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. 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. The limitation for small solar backscattering angles of <25° restricts the satellite coverage to ∼25% of the world area in a single day.

Original languageEnglish
Pages (from-to)5828-5834
Number of pages7
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number21
DOIs
StatePublished - 24 May 2016

Keywords

  • Ccn concentrations
  • Cloud-aerosol interactions
  • Convective clouds
  • Satellite remote sensing

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