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Aerosol indirect effects on glaciated clouds. Part 2 : Sensitivity tests using solute aerosols

Kudzotsa, Innocent LU ; Phillips, Vaughan T J LU and Dobbie, Steven (2016) In Quarterly Journal of the Royal Meteorological Society 142(698). p.1970-1981
Abstract

Sensitivity tests were performed on a midlatitude continental case using a state-of-the-art aerosol–cloud model to determine the salient mechanisms of aerosol indirect effects (AIE) from solute aerosols. The simulations showed that increased solute aerosols doubled cloud-droplet number concentrations and hence reduced cloud particle sizes by about 20% and consequently inhibited warm rain processes, thus enhancing the chances of homogeneous freezing of cloud droplets and aerosols. Cloud fractions and their optical thicknesses increased quite substantially with increasing solute aerosols. Although liquid mixing ratios were boosted, there was, however, a substantial reduction of ice mixing ratios in the upper troposphere, owing to the... (More)

Sensitivity tests were performed on a midlatitude continental case using a state-of-the-art aerosol–cloud model to determine the salient mechanisms of aerosol indirect effects (AIE) from solute aerosols. The simulations showed that increased solute aerosols doubled cloud-droplet number concentrations and hence reduced cloud particle sizes by about 20% and consequently inhibited warm rain processes, thus enhancing the chances of homogeneous freezing of cloud droplets and aerosols. Cloud fractions and their optical thicknesses increased quite substantially with increasing solute aerosols. Although liquid mixing ratios were boosted, there was, however, a substantial reduction of ice mixing ratios in the upper troposphere, owing to the increase in snow production aloft. The predicted total aerosol indirect effect was equal to −9.46 ± 1.4 W m−2. The AIEs of glaciated clouds (−6.33 ± 0.95 W m−2) were greater than those of water-only clouds (−3.13 ± 0.47 W m−2) by a factor of two in this continental case. The higher radiative importance of glaciated clouds compared with water-only clouds emerged from their larger collective spatial extent and their existence above water-only clouds. In addition to the traditional AIEs (glaciation, riming and thermodynamic), the new AIEs sedimentation, aggregation and coalescence were identified.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
aerosol–cloud interactions, CLASIC, cloud microphysics, cloud-resolving models, clouds, glaciated clouds, indirect effects
in
Quarterly Journal of the Royal Meteorological Society
volume
142
issue
698
pages
12 pages
publisher
Royal Meteorological Society
external identifiers
  • scopus:84971330338
  • wos:000380941100008
ISSN
0035-9009
DOI
10.1002/qj.2790
language
English
LU publication?
yes
id
4fb91eda-4ad9-4f94-bb4b-be14047f8ba6
date added to LUP
2017-01-18 15:42:52
date last changed
2017-09-18 11:32:21
@article{4fb91eda-4ad9-4f94-bb4b-be14047f8ba6,
  abstract     = {<p>Sensitivity tests were performed on a midlatitude continental case using a state-of-the-art aerosol–cloud model to determine the salient mechanisms of aerosol indirect effects (AIE) from solute aerosols. The simulations showed that increased solute aerosols doubled cloud-droplet number concentrations and hence reduced cloud particle sizes by about 20% and consequently inhibited warm rain processes, thus enhancing the chances of homogeneous freezing of cloud droplets and aerosols. Cloud fractions and their optical thicknesses increased quite substantially with increasing solute aerosols. Although liquid mixing ratios were boosted, there was, however, a substantial reduction of ice mixing ratios in the upper troposphere, owing to the increase in snow production aloft. The predicted total aerosol indirect effect was equal to −9.46 ± 1.4 W m<sup>−2</sup>. The AIEs of glaciated clouds (−6.33 ± 0.95 W m<sup>−2</sup>) were greater than those of water-only clouds (−3.13 ± 0.47 W m<sup>−2</sup>) by a factor of two in this continental case. The higher radiative importance of glaciated clouds compared with water-only clouds emerged from their larger collective spatial extent and their existence above water-only clouds. In addition to the traditional AIEs (glaciation, riming and thermodynamic), the new AIEs sedimentation, aggregation and coalescence were identified.</p>},
  author       = {Kudzotsa, Innocent and Phillips, Vaughan T J and Dobbie, Steven},
  issn         = {0035-9009},
  keyword      = {aerosol–cloud interactions,CLASIC,cloud microphysics,cloud-resolving models,clouds,glaciated clouds,indirect effects},
  language     = {eng},
  month        = {07},
  number       = {698},
  pages        = {1970--1981},
  publisher    = {Royal Meteorological Society},
  series       = {Quarterly Journal of the Royal Meteorological Society},
  title        = {Aerosol indirect effects on glaciated clouds. Part 2 : Sensitivity tests using solute aerosols},
  url          = {http://dx.doi.org/10.1002/qj.2790},
  volume       = {142},
  year         = {2016},
}