Properties of cloud condensation nuclei (CCN) in the trade wind marine boundary layer of the western North Atlantic

Cloud optical properties in the trade winds over the eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the tropical western North Atla...

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Bibliographic Details
Main Authors: Kristensen, Thomas B., Müller, Thomas, Kandler, Konrad, Benker, Nathalie, Hartmann, Markus, Prospero, Joseph M., Wiedensohler, Alfred, Stratmann, Frank
Format: Article in Journal/Newspaper
Language:English
Published: München : European Geopyhsical Union 2016
Subjects:
boundary layer
cloud condensation nucleus
concentration (composition)
marine atmosphere
optical property
particle size
particulate matter
size distribution
trade wind
550
Aitken
North Atlantic
Online Access:https://doi.org/10.34657/1196
https://oa.tib.eu/renate/handle/123456789/964
Description
Summary:Cloud optical properties in the trade winds over the eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the tropical western North Atlantic, in order to assess the respective roles of inorganic sulfate, organic species, long-range transported mineral dust and sea-salt particles. Measurements were carried out in June–July 2013, on the east coast of Barbados, and included CCN number concentrations, particle number size distributions and offline analysis of sampled particulate matter (PM) and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM) in combination with energy-dispersive X-ray spectroscopy (EDX). During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity parameter κ was inferred, and values in the range 0.2–0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulfate species and organic compounds. publishedVersion

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