Characteristic Vertical Profiles of Cloud Water Composition in Marine Stratocumulus Clouds and Relationships With Precipitation

Alexander B. MacDonald, Hossein Dadashazar, Patrick Y. Chuang, Ewan Crosbie, Hailong Wang, Zhen Wang, Haflidi H. Jonsson, Richard C. Flagan, John H. Seinfeld, Armin Sorooshian

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

This study uses airborne cloud water composition measurements to characterize the vertical structure of air-equivalent mass concentrations of water-soluble species in marine stratocumulus clouds off the California coast. A total of 385 cloud water samples were collected in the months of July and August between 2011 and 2016 and analyzed for water-soluble ionic and elemental composition. Three characteristic profiles emerge: (i) a reduction of concentration with in-cloud altitude for particulate species directly emitted from sources below cloud without in-cloud sources (e.g., Cl and Na+), (ii) an increase of concentration with in-cloud altitude (e.g., NO2 and formate), and (iii) species exhibiting a peak in concentration in the middle of cloud (e.g., non–sea-salt SO4 2−, NO3 , and organic acids). Vertical profiles of rainout parameters such as loss frequency, lifetime, and change in concentration with respect to time show that the scavenging efficiency throughout the cloud depth depends strongly on the thickness of the cloud. Thin clouds exhibit a greater scavenging loss frequency at cloud top, while thick clouds have a greater scavenging loss frequency at cloud base. The implications of these results for treatment of wet scavenging in models are discussed.

Original languageEnglish (US)
Pages (from-to)3704-3723
Number of pages20
JournalJournal of Geophysical Research: Atmospheres
Volume123
Issue number7
DOIs
StatePublished - Apr 16 2018

Keywords

  • aerosol
  • cloud water
  • rainout
  • scavenging
  • sea salt
  • stratocumulus

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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