|Title||Ocean mediation of tropospheric response to reflecting and absorbing aerosols|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Xu Y, Xie SP|
|Journal||Atmospheric Chemistry and Physics|
|Type of Article||Article|
|Keywords||asian summer monsoon; atmosphere; black carbon; circulation; climate responses; driven; emissions; patterns; precipitation; temperature|
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 interhemispheric 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.
|Short Title||Atmos. Chem. Phys.|
Our results show that, despite the fundamental difference in forcing structure, BC and SO4 share common atmospheric response patterns. The common response is mediated by the ocean through sea-surface temperature gradient, and is insensitive to microphysical representations of aerosols. This highlights the importance of ocean–atmosphere interactions in shaping large-scale patterns of climate response (Xie et al., 2010), a process overlooked so far in aerosol–climate connection.