Size-resolved simulations of the aerosol inorganic composition with the new hybrid dissolution solver HyDiS-1.0: description, evaluation and first global modelling results
The dissolution of semi-volatile inorganic gases such as ammonia and nitric acid into the aerosol aqueous phase has an important influence on the composition, hygroscopic properties, and size distribution of atmospheric aerosol particles. The representation of dissolution in global models is cha...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-11-01
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Series: | Geoscientific Model Development |
Online Access: | https://www.geosci-model-dev.net/9/3875/2016/gmd-9-3875-2016.pdf |
Summary: | The dissolution of semi-volatile inorganic gases such as ammonia and nitric
acid into the aerosol aqueous phase has an important influence on the
composition, hygroscopic properties, and size distribution of atmospheric
aerosol particles. The representation of dissolution in global models is
challenging due to inherent issues of numerical stability and computational
expense. For this reason, simplified approaches are often taken, with many
models treating dissolution as an equilibrium process. In this paper we
describe the new dissolution solver HyDiS-1.0, which was developed for the
global size-resolved simulation of aerosol inorganic composition. The solver
applies a hybrid approach, which allows for some particle size classes to
establish instantaneous gas-particle equilibrium, whereas others are treated
time dependently (or dynamically). Numerical accuracy at a competitive
computational expense is achieved by using several tailored numerical
formalisms and decision criteria, such as for the time- and size-dependent
choice between the equilibrium and dynamic approaches. The new hybrid solver
is shown to have numerical stability across a wide range of numerical
stiffness conditions encountered within the atmosphere. For ammonia and
nitric acid, HyDiS-1.0 is found to be in excellent agreement with a fully
dynamic benchmark solver. In the presence of sea salt aerosol, a somewhat
larger bias is found under highly polluted conditions if hydrochloric acid is
represented as a third semi-volatile species. We present first results of the
solver's implementation into a global aerosol microphysics and chemistry
transport model. We find that (1) the new solver predicts surface
concentrations of nitrate and ammonium in reasonable agreement with
observations over Europe, the USA, and East Asia, (2) models that assume
gas-particle equilibrium will not capture the partitioning of nitric acid and
ammonia into Aitken-mode-sized particles, and thus may be missing an
important pathway through which secondary particles may grow to radiation-
and cloud-interacting size, and (3) the new hybrid solver's computational
expense is modest, at around 10 % of total computation time in these
simulations. |
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ISSN: | 1991-959X 1991-9603 |