Disentangling fast and slow responses of the East Asian summer monsoon to reflecting and absorbing aerosol forcings
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, SO<sub>4</sub>) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model ve...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-09-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/17/11075/2017/acp-17-11075-2017.pdf |
Summary: | 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, SO<sub>4</sub>) 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 SO<sub>4</sub> forcing, whereas the weakening is more intensive due to
the changes in tropospheric thermodynamic and dynamic structures in the slow
response (SR) component to SO<sub>4</sub>. The total climate adjustment caused by
SO<sub>4</sub> 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. |
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ISSN: | 1680-7316 1680-7324 |