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| Titel |
A cloud chemistry module for the 3-D cloud-resolving mesoscale model Meso-NH with application to idealized cases |
| VerfasserIn |
M. Leriche, J.-P. Pinty, C. Mari, D. Gazen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 6, no. 4 ; Nr. 6, no. 4 (2013-08-22), S.1275-1298 |
| Datensatznummer |
250084977
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| Publikation (Nr.) |
 copernicus.org/gmd-6-1275-2013.pdf |
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| Zusammenfassung |
| A complete chemical module has been developed for use in the Meso-NH
three-dimensional cloud resolving mesoscale model. This module includes
gaseous- and aqueous-phase chemical reactions that are analysed by a
pre-processor generating the Fortran90 code automatically. The kinetic solver
is based on a Rosenbrock algorithm, which is robust and accurate for
integrating stiff systems and especially multiphase chemistry. The exchange
of chemical species between the gas phase and cloud droplets and raindrops is
computed kinetically by mass transfers considering non-equilibrium between
the gas- and the condensed phases. Microphysical transfers of chemical
species are considered for the various cloud microphysics schemes available,
which are based on one-moment or two-moment schemes. The pH of the droplets
and of the raindrops is diagnosed separately as the root of a high order
polynomial equation. The chemical concentrations in the ice phase are
modelled in a single phase encompassing the two categories of precipitating
ice particles (snow and graupel) of the microphysical scheme. The only
process transferring chemical species in ice is retention during freezing or
riming of liquid hydrometeors. Three idealized simulations are reported,
which highlight the sensitivity of scavenging efficiency to the choice of the
microphysical scheme and the retention coefficient in the ice phase. A
two-dimensional warm, shallow convection case is used to compare the impact
of the microphysical schemes on the temporal evolution and rates of acid
precipitation. Acid wet deposition rates are shown to be overestimated when a
one-moment microphysics scheme is used compared to a two-moment scheme. The
difference is induced by a better prediction of raindrop radius and raindrop
number concentration in the latter scheme. A two-dimensional mixed-phase
squall line and a three-dimensional mixed-phase supercell were simulated to
test the sensitivity of cloud vertical transport to the retention efficiency
of gases in the ice phase. The 2-D and 3-D simulations illustrate that the
retention in ice of a moderately soluble gas such as formaldehyde
substantially decreases its concentration in the upper troposphere. In these
simulations, retention of highly soluble species in the ice phase
significantly increased the wet deposition rates. |
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