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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-913
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
06 Oct 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Aerosol Characteristics in the Entrainment Interface Layer In Relation to the Marine Boundary Layer and Free Troposphere
Hossein Dadashazar1, Rachel A. Braun1, Ewan Crosbie2,3, Patrick Y. Chuang4, Roy K. Woods5, Haflidi H. Jonsson5, and Armin Sorooshian1,6 1Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA
2Science Systems and Applications, Inc., Hampton, VA, USA
3NASA Langley Research Center, Hampton, VA, USA
4Earth and Planetary Sciences, University of California-Santa Cruz, Santa Cruz, CA, USA
5Naval Postgraduate School, Monterey, CA, USA
6Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA
Abstract. This study uses airborne data from two field campaigns off the California coast to characterize aerosol size distribution characteristics in the entrainment interface layer (EIL), a thin and turbulent layer above marine stratocumulus cloud tops, that separates the stratocumulus-topped boundary layer (STBL) from the free troposphere (FT). The vertical bounds of the EIL are defined in this work based on considerations of buoyancy and turbulence using thermodynamic and dynamic data. Aerosol number concentrations are examined from three different probes with varying particle diameter (Dp) ranges: > 3 nm, > 10 nm, 0.11–3.4 µm. Relative to the EIL and FT layers, the sub-cloud (SUB) layer exhibited lower aerosol number concentrations and higher surface area concentrations. High particle number concentrations between 3 and 10 nm in the EIL is indicative of enhanced nucleation, assisted by high actinic fluxes, cool and moist air, and much lower surface area concentrations than the STBL. Slopes of number concentration versus altitude in the EIL were correlated with the particle number concentration difference between the SUB and lower FT layers. The EIL aerosol size distribution was influenced by varying degrees from STBL aerosol versus subsiding FT aerosol depending on the case examined. These results emphasize the important role of the EIL in influencing nucleation and aerosol-cloud-climate interactions.  

Citation: Dadashazar, H., Braun, R. A., Crosbie, E., Chuang, P. Y., Woods, R. K., Jonsson, H. H., and Sorooshian, A.: Aerosol Characteristics in the Entrainment Interface Layer In Relation to the Marine Boundary Layer and Free Troposphere, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-913, in review, 2017.
Hossein Dadashazar et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
 
RC1: 'Reviewer Comments', Anonymous Referee #1, 06 Nov 2017 Printer-friendly Version Supplement 
 
RC2: 'Review', Anonymous Referee #2, 10 Dec 2017 Printer-friendly Version 
 
AC1: 'Response to referee 1', Hossein Dadashazar, 26 Dec 2017 Printer-friendly Version Supplement 
 
AC2: 'Response to referee 2', Hossein Dadashazar, 26 Dec 2017 Printer-friendly Version Supplement 
Hossein Dadashazar et al.

Data sets

A Multi-Year Data Set on Aerosol-Cloud-Precipitation-Meteorology Interactions for Marine Stratocumulus Clouds
A. Sorooshian
https://doi.org/10.6084/m9.figshare.5099983.v3
Hossein Dadashazar et al.

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Short summary
This study shows with airborne data that in the thin layer above stratocumulus clouds, the Entrainment Interface Layer (EIL), aerosol size distributions are influenced both by new particle formation and from pollutants above and below the EIL. These results are important with regard to understanding aerosol-cloud-climate interactions as the aerosol in this layer can influence the characteristics of stratocumulus clouds, which are the dominant cloud type by global area.
This study shows with airborne data that in the thin layer above stratocumulus clouds, the...
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