Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 15, 5827-5833, 2015
https://doi.org/10.5194/acp-15-5827-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 May 2015
Ocean mediation of tropospheric response to reflecting and absorbing aerosols
Y. Xu1 and S.-P. Xie2 1National Center for Atmospheric Research, Boulder, CO 80303, USA
2Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
Abstract. Radiative forcing by reflecting (e.g., sulfate, SO4) and absorbing (e.g., black carbon, BC) aerosols is distinct: the former cools the planet by reducing solar radiation at the top of the atmosphere and the surface, without largely affecting the atmospheric column, while the latter heats the atmosphere directly. Despite the fundamental difference in forcing, here we show that the structure of the tropospheric response is remarkably similar between the two types of aerosols, featuring a deep vertical structure of temperature change (of opposite sign) at the Northern Hemisphere (NH) mid-latitudes. The deep temperature structure is anchored by the slow response of the ocean, as a large meridional sea surface temperature (SST) gradient drives an anomalous inter-hemispheric Hadley circulation in the tropics and induces atmospheric eddy adjustments at the NH mid-latitudes. The tropospheric warming in response to projected future decline in reflecting aerosols poses additional threats to the stability of mountain glaciers in the NH. Additionally, robust tropospheric response is unique to aerosol forcing and absent in the CO2 response, which can be exploited for climate change attribution.

Citation: Xu, Y. and Xie, S.-P.: Ocean mediation of tropospheric response to reflecting and absorbing aerosols, Atmos. Chem. Phys., 15, 5827-5833, https://doi.org/10.5194/acp-15-5827-2015, 2015.
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Short summary
Strong solar heating by absorbing aerosols (black carbon) is considered more effective in inducing atmospheric circulation change than reflecting aerosols (sulfate), which do not have direct atmospheric heating effect. Surprisingly, we show that reflecting aerosols induce tropospheric temperature and circulation response similar to that induced by absorbing aerosols. The common response is mediated by the ocean through SST gradient, a process overlooked so far in aerosol-climate connection.
Strong solar heating by absorbing aerosols (black carbon) is considered more effective in...
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