Global modeling of heterogeneous hydroxymethanesulfonate chemistry
<p>Hydroxymethanesulfonate (HMS) has recently been identified as an abundant organosulfur compound in aerosols during winter haze episodes in northern China. It has also been detected in other regions although the concentrations are low. Because of the sparse field measurements, the global sig...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/21/457/2021/acp-21-457-2021.pdf |
| Summary: | <p>Hydroxymethanesulfonate (HMS) has recently been
identified as an abundant organosulfur compound in aerosols during winter
haze episodes in northern China. It has also been detected in other regions
although the concentrations are low. Because of the sparse field
measurements, the global significance of HMS and its spatial and seasonal
patterns remain unclear. Here, we modify and add to the implementation of
HMS chemistry in the GEOS-Chem chemical transport model and conduct multiple
global simulations. The model accounts for cloud entrainment and
gas–aqueous mass transfer within the rate expressions for heterogeneous
sulfur chemistry. Our simulations can generally reproduce quantitative HMS
observations from Beijing and show that East Asia has the highest HMS
concentration, followed by Europe and North America. The simulated HMS shows
a seasonal pattern with higher values in the colder period. Photochemical
oxidizing capacity affects the competition of formaldehyde with oxidants
(such as ozone and hydrogen peroxide) for sulfur dioxide and is a key factor
influencing the seasonality of HMS. The highest average HMS concentration
(1–3 <span class="inline-formula">µg m<sup>−3</sup></span>) and HMS <span class="inline-formula">∕</span> sulfate molar ratio (0.1–0.2) are found in
northern China in winter. The simulations suggest that aqueous clouds act as
the major medium for HMS chemistry while aerosol liquid water may play a
role if its rate constant for HMS formation is greatly enhanced compared to
cloud water.</p> |
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| ISSN: | 1680-7316 1680-7324 |