Soluble mass, hygroscopic growth, and droplet activation of coated soot particles during LACIS Experiment in November (LExNo)

Abstract

The LACIS Experiment in November (LExNo) campaign was conducted in November 2005 at the Atmospheric Composition Change the European Network of Excellence (ACCENT) site Leipzig Aerosol Cloud Interaction Simulator (LACIS). The goal of LExNo was to provide deeper insight into the activation properties of coated soot particles imitating aged combustion aerosol particles. The aerosols were prepared by starting with spark‐generated soot particles. In some experiments the soot particles were compacted by exposure to propanol vapor; in others this step was bypassed. The soot was thermally coated with ammonium sulfate, levoglucosan, or a mixture of both ammonium sulfate and levoglucosan. The synthesized particles were investigated using aerosol mass spectrometry, a Hygroscopicity Tandem differential mobility analyzer, two Wyoming static diffusion cloud condensation nuclei (CCN) instruments, a Droplet Measurement Technologies continuous flow CCN instrument, and LACIS. A close correlation between the hygroscopic growth factor at 98% relative humidity and the critical supersaturation of CCN activation was observed. Closure between hygroscopic growth, CCN activation, and chemical composition of the investigated particles was achieved with two different single‐parameter Köhler model approaches and with a third approach, a standard Köhler model using as input parameter the soluble mass as determined by aerosol mass spectrometry.

Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

“…No (complete) activation was found for soot from aviation fuel, wood and crude oil. Henning et al (2010) observed, that coated spark soot acts as CCN (d p,0 = 85 nm activated between 0.3 and 0.6 %). Zhang et al (2008) investigated the activation of sulfuric acid coated flame soot at two supersaturations (0.2 and 0.4 %), but they found no activation for the uncoated soot at the same supersaturations.…”

“…The GF increased with increasing sulfur content of the fuel. Weingartner et al (1997) and Henning et al (2010) used the same type of spark generator with nitrogen as carrier gas as was used in this study. They observed no hygroscopic growth for the uncoated spark soot, but after coating with soluble substances a hygroscopic growth occurred .…”

A simple relationship between cloud drop number concentration and precursor aerosol concentration for the regions of Earth's large marine stratocumulus decks

“…In consideration of these issues, particularly the need for large scale coverage with its implied mandate for remote retrieval of aerosol properties that can predict CDNC, numerous studies have explored possible simplifications to the aerosol-CDNC relationship, for example using such parameters as size dependent hygroscopicity (e.g., Petters and Kreidenweiss, 2008;Henning et al, 2010). A particularly simplified relationship has been suggested by the study of Dusek et al (2006).…”

Ambient black carbon particle hygroscopic properties controlled by mixing state and composition

“…The extended classic Köhler theory has been applied for most of the studies to include the insolubility of BC inclusion (i.e. Weingatner et al, 1997;Zhang et al, 2008;Henning et al, 2010), which has mostly explained the increased hygroscopicity of soot particles by attributing the hygroscopicity from each of the components present.…”