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Satellite retrieval of cloud condensation nuclei concentrations in marine stratocumulus by using clouds as CCN chambers
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  • Avichay Efraim,
  • Daniel Rosenfeld,
  • Julia Schmale,
  • Yannian Zhu
Avichay Efraim
Hebrew University of Jerusalem

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Daniel Rosenfeld
Hebrew University of Jerusalem
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Julia Schmale
Extreme Environments Research Laboratory
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Yannian Zhu
Meteorological Institute of Shaanxi Province
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A new methodology for satellite retrieval of cloud condensation nuclei (CCN) in shallow marine boundary layer clouds is developed and validated in this study. The methodology is based on retrieving cloud base drop concentrations (Nd) and updrafts (Wb), and calculating the supersaturation (S) based on that. Then Nd is the CCN at S. 50 The accuracy of the satellite retrievals was validated against ship borne measurements of CCN done in recent campaigns in the Southern Oceans (ACE-SPACE, MARCUS & PEGASO [2015-2018]) and in the subtropics (MAGIC [2012-2013]). The satellite retrieve Nd and S at cloud base was related to the actually measured CCN(S) at sea surface. The main findings show that: (a) coupled clouds have good agreement 55 between satellite retrievals and ship measurements of CCN(S); (b) the best agreement is achieved when using the brightest 10% of the clouds, and accounting for their adiabatic fraction, as measured by aircrafts; (c) most of the decoupled clouds had much lower CCN(S) than at the underlying surface. This means that most CCN originate from the surface and not from the free troposphere. This validates the satellite retrievals and 60 allows us to further quantify the relationships between CCN(S) and cloud microphysical properties.
27 Aug 2020Published in Journal of Geophysical Research: Atmospheres volume 125 issue 16. 10.1029/2020JD032409