Aerosol characteristics in the entrainment interface layer in relation to the marine boundary layer and free troposphere

Hossein Dadashazar, Rachel Braun, Ewan Crosbie, Patrick Chuang, Roy Woods, Haflidi Jonsson, Armin Sorooshian

Research output: Contribution to journalArticle

10 Scopus citations

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, which 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: >ĝ€̄3ĝ€̄nm, >ĝ€̄10ĝ€̄nm, and 0.11-3.4ĝ€̄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 10ĝ€̄nm in the EIL are 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.

Original languageEnglish (US)
Pages (from-to)1495-1506
Number of pages12
JournalAtmospheric Chemistry and Physics
Volume18
Issue number3
DOIs
StatePublished - Jan 1 2018

ASJC Scopus subject areas

  • Atmospheric Science

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