Isoprene-derived secondary organic aerosol in the global aerosol–chemistry–climate model ECHAM6.3.0–HAM2.3–MOZ1.0
<p>Within the framework of the global chemistry climate model ECHAM–HAMMOZ, a novel explicit coupling between the sectional aerosol model HAM-SALSA and the chemistry model MOZ was established to form isoprene-derived secondary organic aerosol (iSOA). Isoprene oxidation in the chemistry mode...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-08-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/11/3235/2018/gmd-11-3235-2018.pdf |
| Summary: | <p>Within the framework of the global chemistry climate model
ECHAM–HAMMOZ, a novel explicit coupling between the sectional aerosol model
HAM-SALSA and the chemistry model MOZ was established to form isoprene-derived secondary organic aerosol (iSOA). Isoprene oxidation in the chemistry
model MOZ is described by a semi-explicit scheme consisting of 147 reactions
embedded in a detailed atmospheric chemical mechanism with a total of
779 reactions. Semi-volatile and low-volatile compounds produced during
isoprene photooxidation are identified and explicitly partitioned by
HAM-SALSA. A group contribution method was used to estimate their evaporation
enthalpies and corresponding saturation vapor pressures, which are used by
HAM-SALSA to calculate the saturation concentration of each iSOA precursor.
With this method, every single precursor is tracked in terms of condensation
and evaporation in each aerosol size bin. This approach led to the
identification of dihydroxy dihydroperoxide (ISOP(OOH)2) as a main
contributor to iSOA formation. Further, the reactive uptake of isoprene
epoxydiols (IEPOXs) and isoprene-derived glyoxal were included as iSOA
sources. The parameterization of IEPOX reactive uptake includes a dependency
on aerosol pH value. This model framework connecting semi-explicit isoprene
oxidation with explicit treatment of aerosol tracers leads to a global
annual average isoprene SOA yield of 15 % relative to the primary
oxidation of isoprene by OH, NO<sub>3</sub> and ozone. With 445.1 Tg
(392.1 Tg C) isoprene emitted, an iSOA source of 138.5 Tg (56.7 Tg C) is
simulated. The major part of iSOA in ECHAM–HAMMOZ is produced by IEPOX
at 42.4 Tg (21.0 Tg C) and ISOP(OOH)2 at 78.0 Tg (27.9 Tg C). The main sink
process is particle wet deposition, which removes 133.6 (54.7 Tg C). The
average iSOA burden reaches 1.4 Tg (0.6 Tg C) in the year 2012.</p> |
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| ISSN: | 1991-959X 1991-9603 |