scholarly journals Temperature-dependent formation of NaCl dihydrate in levitated NaCl and sea salt aerosol particles

2016 ◽  
Vol 145 (24) ◽  
pp. 244503 ◽  
Author(s):  
Andreas Peckhaus ◽  
Alexei Kiselev ◽  
Robert Wagner ◽  
Denis Duft ◽  
Thomas Leisner
Keyword(s):  
Aerosol Particles ◽  
Sea Salt ◽  
Temperature Dependent ◽  
Sea Salt Aerosol

scholarly journals Depositional ice nucleation onto hydrated NaCl particles: a new mechanism for ice formation in the troposphere

2011 ◽  
Vol 11 (8) ◽  
pp. 23139-23167 ◽  
Author(s):  
M. E. Wise ◽  
K. J. Baustian ◽  
T. Koop ◽  
M. A. Freedman ◽  
E. J. Jensen ◽  
...  
Keyword(s):  
Marine Boundary Layer ◽  
Aerosol Particles ◽  
Ice Nucleation ◽  
Sea Salt ◽  
Ice Formation ◽  
Radiation Balance ◽  
Atmospheric Conditions ◽  
Hydrated Form ◽  
Sea Salt Aerosol ◽  
Ice Nuclei

Abstract. Sea-salt aerosol particles (SSA) are ubiquitous in the marine boundary layer and over coastal areas. Therefore SSA have ability to directly and indirectly affect the Earth's radiation balance. The influence SSA have on climate is related to their water uptake and ice nucleation characteristics. In this study, optical microscopy coupled with Raman spectroscopy was used to detect the formation of an NaCl hydrate that could form under atmospheric conditions. NaCl(s) particles deliquesced at the well established value of 75.7 ± 2.5 % RH. NaCl(aq) particles effloresced to a mixture of hydrated and non-hydrated particles at temperatures between 236 and 252 K. The aqueous particles effloresced into the non-hydrated form at temperatures warmer than 252 K. At temperatures colder than 236 K all particles effloresced into the hydrated form. The deliquescence relative humidities (DRH) of hydrated NaCl(s) particles ranged from 76.6 to 93.2 % RH. Based on the measured DRH and efflorescence relative humidities (ERH), we estimate crystalline NaCl particles could be in the hydrated form 40–80 % of the time in the troposphere. Additionally, the ice nucleating abilities of NaCl(s) and hydrated NaCl(s) were determined at temperatures ranging from 221 to 238 K. NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.11 ± 0.07. Hydrated NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.02 ± 0.04. When a mixture of hydrated and anhydrous NaCl(s) particles was present in the same sample, ice preferentially nucleated on the hydrated particles 100 % of the time. While both types of particles are efficient ice nuclei, hydrated NaCl(s) particles are better ice nuclei than NaCl(s) particles.

scholarly journals Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

2002 ◽  
Vol 2 (1) ◽  
pp. 1-28 ◽  
Author(s):  
M. Wachsmuth ◽  
H. W. Gäggeler ◽  
R. von Glasow ◽  
M. Ammann
Keyword(s):  
Ozone Depletion ◽  
Aerosol Particles ◽  
Accommodation Coefficient ◽  
Sea Salt ◽  
Sodium Bromide ◽  
Radioactive Isotopes ◽  
The Arctic ◽  
Sea Salt Aerosol ◽  
Mass Accommodation Coefficient ◽  
Salt Brine

Abstract. Uptake of HOBr on sea salt aerosol, sea salt brine or ice is believed to be a key process providing a source of photolabile bromine (Br2) and sustaining ozone depletion cycles in the arctic troposphere. In the present study, uptake of HOBr on sodium bromide (NaBr) aerosol particles was investigated at an extremely low HOBr concentration of 300 cm-3 using the short-lived radioactive isotopes 83-86Br. Under these conditions, at maximum one HOBr molecule was taken up per particle. The rate of uptake was clearly limited by the mass accommodation coefficient, which was calculated to be 0.6±0.2. This value is a factor of 10 larger than estimates used in earlier models. The atmospheric implications are discussed using the box model "MOCCA'', showing that the increase of the accommodation coefficient of HOBr by a factor of 10 only slightly affects net ozone loss, but significantly increases chlorine release.

scholarly journals A parameterization of size resolved below cloud scavenging of aerosols by rain

2006 ◽  
Vol 6 (1) ◽  
pp. 1355-1384 ◽  
Author(s):  
J. S. Henzing ◽  
D. J. L. Olivié ◽  
P. F. J. Van Velthoven
Keyword(s):  
Transport Model ◽  
Aerosol Particles ◽  
Droplet Size Distribution ◽  
Sea Salt ◽  
Total Removal ◽  
Sea Salt Aerosol ◽  
Aerosol Particle Size ◽  
Full Interaction ◽  
Cloud Scavenging ◽  
Year 2000

Abstract. A size dependent parameterization for the removal of aerosol particles by falling rain droplets is developed. Scavenging coefficients are calculated explicitly as a function of aerosol particle size and precipitation intensity including the full interaction of rain droplet size distribution and aerosol particles. The actual parameterization is a simple and accurate three-parameter fit through these pre-calculated scavenging coefficients. The parameterization is applied in the global chemistry transport model TM4 and the importance of below-cloud scavenging relative to other removal mechanisms is investigated for sea salt aerosol. For a full year run (year 2000), we find that below-cloud scavenging accounts for 12% of the total removal of super-micron aerosol. At mid-latitudes of both hemispheres the fractional contribution of below-cloud scavenging to the total removal of super-micron sea salt is about 30% with regional maxima exceeding 50%. Below-cloud scavenging reduces the global average super-micron aerosol lifetime from 2.47 to 2.16 days in our simulations. Despite large uncertainties in precipitation, relative humidity, and water uptake by aerosol particles, we conclude that below cloud scavenging is likely an important sink for super-micron sized sea salt aerosol particles that needs to be included in size-resolved aerosol models.

scholarly journals Condensational Growth of Drops Formed on Giant Sea-Salt Aerosol Particles

2017 ◽  
Vol 74 (3) ◽  
pp. 679-697 ◽  
Author(s):  
Jørgen B. Jensen ◽  
Alison D. Nugent
Keyword(s):  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Pure Water ◽  
Sea Salt ◽  
Cloud Formation ◽  
Cloud Base ◽  
Growth Equation ◽  
Marine Stratocumulus ◽  
Sea Salt Aerosol ◽  
Condensational Growth

Abstract The most basic aspect of cloud formation is condensational growth onto cloud condensation nuclei (CCN). As such, condensational growth of cloud drops is often assumed to be a well-understood process described by the drop growth equation. When this process is represented in models, CCN activate into cloud drops at cloud base, and it is often assumed that drops consist of pure water or that the hygroscopic contribution after drop activation is small because of the inclusion of only small CCN. Drop growth rate in adiabatic ascent in such models is proportional to supersaturation and assumed to be inversely proportional to the drop radius, thereby making the drop spectrum narrow with altitude. However, the present study demonstrates that drop growth on giant sea-salt aerosol particles (GCCN; dry radius 0.5 m) behaves differently. For typical marine stratocumulus updrafts and for drops grown on GCCN with sizes m, these drops typically remain concentrated salt solutions. Because of this, their condensational growth is accelerated, and they rapidly attain precipitation drop sizes through condensation only. Additionally, drops formed on GCCN may also grow by condensation in cloudy downdrafts. The strong effect of condensation on GCCN is important when carried through to calculating rain-rate contribution as a function of aerosol size. GCCN larger than 2 m account for most of the rainfall rate in the modeled precipitating marine stratocumulus.

Heterogeneous sulfur conversion in sea-salt aerosol particles: the role of aerosol water content and size distribution

1991 ◽  
Vol 25 (8) ◽  
pp. 1479-1487 ◽  
Author(s):  
H. Sievering ◽  
J. Boatman ◽  
J. Galloway ◽  
W. Keene ◽  
Y. Kim ◽  
...  
Keyword(s):  
Water Content ◽  
Size Distribution ◽  
Aerosol Particles ◽  
Sea Salt ◽  
Sea Salt Aerosol

scholarly journals Integrating biomass, sulphate and sea-salt aerosol responses into a microphysical chemical parcel model: implications for climate studies

2007 ◽  
Vol 365 (1860) ◽  
pp. 2659-2674 ◽  
Author(s):  
S Ghosh ◽  
M.H Smith ◽  
A Rap
Keyword(s):  
Radiative Forcing ◽  
General Circulation ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
Sea Salt ◽  
Radiative Properties ◽  
Radiation Budget ◽  
Sulphate Aerosol ◽  
Salt Loading ◽  
Sea Salt Aerosol

Aerosols are known to influence significantly the radiative budget of the Earth. Although the direct effect (whereby aerosols scatter and absorb solar and thermal infrared radiation) has a large perturbing influence on the radiation budget, the indirect effect (whereby aerosols modify the microphysical and hence the radiative properties and amounts of clouds) poses a greater challenge to climate modellers. This is because aerosols undergo chemical and physical changes while in the atmosphere, notably within clouds, and are removed largely by precipitation. The way in which aerosols are processed by clouds depends on the type, abundance and the mixing state of the aerosols concerned. A parametrization with sulphate and sea-salt aerosol has been successfully integrated within the Hadley Centre general circulation model (GCM). The results of this combined parametrization indicate a significantly reduced role, compared with previous estimates, for sulphate aerosol in cloud droplet nucleation and, consequently, in indirect radiative forcing. However, in this bicomponent system, the cloud droplet number concentration, N d (a crucial parameter that is used in GCMs for radiative transfer calculations), is a smoothly varying function of the sulphate aerosol loading. Apart from sea-salt and sulphate aerosol particles, biomass aerosol particles are also present widely in the troposphere. We find that biomass smoke can significantly perturb the activation and growth of both sulphate and sea-salt particles. For a fixed salt loading, N d increases linearly with modest increases in sulphate and smoke masses, but significant nonlinearities are observed at higher non-sea-salt mass loadings. This non-intuitive N d variation poses a fresh challenge to climate modellers.

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