Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 11075-11088, 2017
https://doi.org/10.5194/acp-17-11075-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
19 Sep 2017
Disentangling fast and slow responses of the East Asian summer monsoon to reflecting and absorbing aerosol forcings
Zhili Wang1, Lei Lin2, Meilin Yang3, Yangyang Xu4, and Jiangnan Li5 1State Key Laboratory of Severe Weather and Key Laboratory of Atmospheric Chemistry of CMA, Chinese Academy of Meteorological Sciences, Beijing, 100081, China
2School of Atmospheric Sciences and Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Zhuhai, 519000, China
3Institute of Urban Meteorology, China Meteorological Administration, Beijing, 100089, China
4Department of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, USA
5Canadian Centre for Climate Modelling and Analysis, Science and Technology Branch, Environment Canada, Victoria, V8P5C2, Canada
Abstract. We examine the roles of fast and slow responses in shaping the total equilibrium response of the East Asian summer monsoon (EASM) to reflecting (sulfate, SO4) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model version 1 (CESM1). Our results show that there is a clear distinction between fast and slow responses of the EASM to aerosol forcings and the slow climate response due to aerosol-induced change in sea surface temperature (SST) plays an important role in the impacts of aerosols on the EASM. The EASM is weakened by a decrease in land–sea surface thermal contrast in the fast response (FR) component to SO4 forcing, whereas the weakening is more intensive due to the changes in tropospheric thermodynamic and dynamic structures in the slow response (SR) component to SO4. The total climate adjustment caused by SO4 is a significant weakening of the EASM and a decrease in precipitation. The BC-induced fast adjustment strengthens the EASM both by increasing the local land–sea surface thermal contrast and shifting the East Asian subtropical jet (EASJ) northwards. The BC-induced slow climate adjustment, however, weakens the EASM through altering the atmospheric temperature and circulation. Consequently, the EASM is slightly enhanced, especially north of 30° N, in the total response (TR) to BC. The spatial patterns of precipitation change over East Asia due to BC are similar in the total response and slow response. This study highlights the importance of ocean response to aerosol forcings in driving the changes of the EASM.

Citation: Wang, Z., Lin, L., Yang, M., Xu, Y., and Li, J.: Disentangling fast and slow responses of the East Asian summer monsoon to reflecting and absorbing aerosol forcings, Atmos. Chem. Phys., 17, 11075-11088, https://doi.org/10.5194/acp-17-11075-2017, 2017.
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Short summary
There is still debate over whether the total aerosols enhance or weaken the East Asian summer monsoon (EASM). This could be related to both the complicated nature of aerosol chemical compositions and ocean responses to aerosols. Our results show that there is a clear distinction between fast and slow responses of the EASM to scattering and absorbing aerosols, and the slow response due to aerosol-induced change in sea surface temperature plays an important role in driving the change of the EASM.
There is still debate over whether the total aerosols enhance or weaken the East Asian summer...
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