the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 01 Nov 2022
Assessment of the impacts of cloud chemistry on surface SO2 and sulfate levels in typical regions of China
Abstract. A regional online chemical weather model WRF/ CUACE (China Meteorological Administration Unified Atmospheric Chemistry Environment) was used to assess the contributions of cloud chemistry to the SO2 and sulfate levels in typical regions in China. By comparing with several time series of in-situ cloud chemical observations on Mountain Tai in Shandong Province of China, the CUACE cloud chemistry scheme was found to well reproduce the cloud processing the consumptions of H2O2, O3 and SO2, and consequently was used in the regional assessment for a heavy pollution episode and monthly average in December 2016. During cloud availability in heavy pollution episode, the sulfate production increases 40–80 % and SO2 reduces over 80 %. During the heavy pollution episode, it is found that the cloud chemistry mainly affects the middle and lower troposphere below 5 km as well as within the boundary layer, and contributes significantly to SO2 reduction and sulfate increase in east-central China. Among the regions of North China Plain (NCP), Yangtze River Delta (YRD) and Sichuan Basin (SCB), the SCB is mostly affected by the cloud chemistry, with the average SO2 abatement up to about 1–15 ppb and sulfate increase up to more than 50 μg m-3, followed by YRD where the contribution of cloud chemistry is still significant, averaging up to 1–3 ppb for SO2 abatement and 5–20 μg/m3 for sulfate increase. The cloud chemistry contribution to PRD and NCP are not significant and weaker than other two regions due to lighter pollution and less water vapor, respectively. In addition, the average contribution of cloud chemistry during the pollution period was significantly greater than that for all December. This study provides a way to analyze the over-estimate phenomenon of SO2 in many chemical transport models.
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RC1: 'Comment on acp-2022-716', Anonymous Referee #1, 07 Dec 2022
This manuscript presents a study of cloud-based SO2 processing for sulfate formation over China using a regional coupled chemistry-weather model. The chemistry the study is based on is at least 7 years out of date. It has been known for many years that cloudwater processing is insufficient to explain sulfate formation in China, particularly during heavy pollution events, and aerosol chemistry is crucial for understanding this phenomenon (there is extensive literature on this, summarized, for example, in the reviews by Tilgner et al. ACP 2021 and Liu et al. ES&T 2021). This is not acknowledged or discussed in the manuscript. An intercomparison of the simulation results with field data is shown which, unsurprisingly, does not show very good agreement. The presentation quality is also low, with multiple typographical errors. I don't recommend publication of this study in ACP.
Citation: https://doi.org/10.5194/acp-2022-716-RC1 -
AC1: 'Reply on RC1', Sunling Gong, 05 Feb 2023
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-716/acp-2022-716-AC1-supplement.pdf
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AC1: 'Reply on RC1', Sunling Gong, 05 Feb 2023
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RC2: 'Comment on acp-2022-716', Anonymous Referee #2, 16 Dec 2022
Sulfate aerosols play a significant role in global radiative forcing, however, its formation mechanisms remain uncertain, especially in severe polluted conditions. Lu et al. assess the contributions of cloud chemistry to the SO2 and sulfate levels in typical regions in China using a WRF/CUACE model. They found that Sichuan Basin is mostly affected by the cloud chemistry, followed by YRD, NCP, and PRD regions. This paper provides some valuable information on the modeling of SO2 and sulfate levels, however, the manuscript is not very clear in motivating the work. In particular, previous studies have demonstrated that cloud chemistry cannot explain the sulfate formation during haze events and aerosol chemistry plays an important role instead (Wang et al., 2021;Cheng et al., 2016;Zheng et al., 2015;Wang et al., 2014). These studies are not referred to. I also have some concerns regarding data analysis that must be addressed before the paper can be considered for publication.
Major comments:
The authors stated in Lines 59-61 that few models have assessed the contribution of cloud chemistry to sulfate formation in polluted regions in China. This is not true. A lot of previous studies have demonstrated that cloud chemistry is insufficient to explain sulfate formation in polluted regions in China. The improvement of the WRF/CUACE model used in this study compared to previous models is not well justified. What is the advantage to use WRF/CUACE model?
Lines 111-112: Henry’s law constant of SO2 was corrected from 1.23 to 1.23×10-3 M/atm in the model. However, the correct value should be 1.23 M/atm (Seinfeld and Pandis, 2016). Are all the model results in this study based on an incorrect Henry’s law constant of SO2?
Regarding the validation of WRF/CUACE, only the modeled hourly SO2 and oxidants concentrations are compared to measurements in Figure 2. Are the sulfate concentrations comparable? This is key information for evaluating the performance of this model. Also, the observed and modeled sulfate concentrations should be compared in Tables 5 and 6.
References:
Cheng, Y., Zheng, G., Wei, C., Mu, Q., Zheng, B., Wang, Z., Gao, M., Zhang, Q., He, K., Carmichael, G., Pöschl, U., and Su, H.: Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China, Sci. Adv., 2, 10.1126/sciadv.1601530, 2016.
Seinfeld, J. H., and Pandis, S. N.: Atmospheric chemistry and physics: from air pollution to climate change, John Wiley & Sons, 2016.
Wang, W., Liu, M., Wang, T., Song, Y., Zhou, L., Cao, J., Hu, J., Tang, G., Chen, Z., Li, Z., Xu, Z., Peng, C., Lian, C., Chen, Y., Pan, Y., Zhang, Y., Sun, Y., Li, W., Zhu, T., Tian, H., and Ge, M.: Sulfate formation is dominated by manganese-catalyzed oxidation of SO2 on aerosol surfaces during haze events, Nat Commun, 12, 1993, 10.1038/s41467-021-22091-6, 2021.
Wang, Y., Zhang, Q., Jiang, J., Zhou, W., Wang, B., He, K., Duan, F., Zhang, Q., Philip, S., and Xie, Y.: Enhanced sulfate formation during China's severe winter haze episode in January 2013 missing from current models, J Geophys. Res. Atmos., 119, 10,425-410,440, https://doi.org/10.1002/2013JD021426, 2014.
Zheng, B., Zhang, Q., Zhang, Y., He, K. B., Wang, K., Zheng, G. J., Duan, F. K., Ma, Y. L., and Kimoto, T.: Heterogeneous chemistry: a mechanism missing in current models to explain secondary inorganic aerosol formation during the January 2013 haze episode in North China, Atmos. Chem. Phys., 15, 2031-2049, 10.5194/acp-15-2031-2015, 2015.
Citation: https://doi.org/10.5194/acp-2022-716-RC2 -
AC2: 'Reply on RC2', Sunling Gong, 05 Feb 2023
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-716/acp-2022-716-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Sunling Gong, 05 Feb 2023
Status: closed
-
RC1: 'Comment on acp-2022-716', Anonymous Referee #1, 07 Dec 2022
This manuscript presents a study of cloud-based SO2 processing for sulfate formation over China using a regional coupled chemistry-weather model. The chemistry the study is based on is at least 7 years out of date. It has been known for many years that cloudwater processing is insufficient to explain sulfate formation in China, particularly during heavy pollution events, and aerosol chemistry is crucial for understanding this phenomenon (there is extensive literature on this, summarized, for example, in the reviews by Tilgner et al. ACP 2021 and Liu et al. ES&T 2021). This is not acknowledged or discussed in the manuscript. An intercomparison of the simulation results with field data is shown which, unsurprisingly, does not show very good agreement. The presentation quality is also low, with multiple typographical errors. I don't recommend publication of this study in ACP.
Citation: https://doi.org/10.5194/acp-2022-716-RC1 -
AC1: 'Reply on RC1', Sunling Gong, 05 Feb 2023
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-716/acp-2022-716-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Sunling Gong, 05 Feb 2023
-
RC2: 'Comment on acp-2022-716', Anonymous Referee #2, 16 Dec 2022
Sulfate aerosols play a significant role in global radiative forcing, however, its formation mechanisms remain uncertain, especially in severe polluted conditions. Lu et al. assess the contributions of cloud chemistry to the SO2 and sulfate levels in typical regions in China using a WRF/CUACE model. They found that Sichuan Basin is mostly affected by the cloud chemistry, followed by YRD, NCP, and PRD regions. This paper provides some valuable information on the modeling of SO2 and sulfate levels, however, the manuscript is not very clear in motivating the work. In particular, previous studies have demonstrated that cloud chemistry cannot explain the sulfate formation during haze events and aerosol chemistry plays an important role instead (Wang et al., 2021;Cheng et al., 2016;Zheng et al., 2015;Wang et al., 2014). These studies are not referred to. I also have some concerns regarding data analysis that must be addressed before the paper can be considered for publication.
Major comments:
The authors stated in Lines 59-61 that few models have assessed the contribution of cloud chemistry to sulfate formation in polluted regions in China. This is not true. A lot of previous studies have demonstrated that cloud chemistry is insufficient to explain sulfate formation in polluted regions in China. The improvement of the WRF/CUACE model used in this study compared to previous models is not well justified. What is the advantage to use WRF/CUACE model?
Lines 111-112: Henry’s law constant of SO2 was corrected from 1.23 to 1.23×10-3 M/atm in the model. However, the correct value should be 1.23 M/atm (Seinfeld and Pandis, 2016). Are all the model results in this study based on an incorrect Henry’s law constant of SO2?
Regarding the validation of WRF/CUACE, only the modeled hourly SO2 and oxidants concentrations are compared to measurements in Figure 2. Are the sulfate concentrations comparable? This is key information for evaluating the performance of this model. Also, the observed and modeled sulfate concentrations should be compared in Tables 5 and 6.
References:
Cheng, Y., Zheng, G., Wei, C., Mu, Q., Zheng, B., Wang, Z., Gao, M., Zhang, Q., He, K., Carmichael, G., Pöschl, U., and Su, H.: Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China, Sci. Adv., 2, 10.1126/sciadv.1601530, 2016.
Seinfeld, J. H., and Pandis, S. N.: Atmospheric chemistry and physics: from air pollution to climate change, John Wiley & Sons, 2016.
Wang, W., Liu, M., Wang, T., Song, Y., Zhou, L., Cao, J., Hu, J., Tang, G., Chen, Z., Li, Z., Xu, Z., Peng, C., Lian, C., Chen, Y., Pan, Y., Zhang, Y., Sun, Y., Li, W., Zhu, T., Tian, H., and Ge, M.: Sulfate formation is dominated by manganese-catalyzed oxidation of SO2 on aerosol surfaces during haze events, Nat Commun, 12, 1993, 10.1038/s41467-021-22091-6, 2021.
Wang, Y., Zhang, Q., Jiang, J., Zhou, W., Wang, B., He, K., Duan, F., Zhang, Q., Philip, S., and Xie, Y.: Enhanced sulfate formation during China's severe winter haze episode in January 2013 missing from current models, J Geophys. Res. Atmos., 119, 10,425-410,440, https://doi.org/10.1002/2013JD021426, 2014.
Zheng, B., Zhang, Q., Zhang, Y., He, K. B., Wang, K., Zheng, G. J., Duan, F. K., Ma, Y. L., and Kimoto, T.: Heterogeneous chemistry: a mechanism missing in current models to explain secondary inorganic aerosol formation during the January 2013 haze episode in North China, Atmos. Chem. Phys., 15, 2031-2049, 10.5194/acp-15-2031-2015, 2015.
Citation: https://doi.org/10.5194/acp-2022-716-RC2 -
AC2: 'Reply on RC2', Sunling Gong, 05 Feb 2023
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-716/acp-2022-716-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Sunling Gong, 05 Feb 2023
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