Abstract
Abstract. Mineral dust aerosol can be transported over the nearby oceans and influence the energy balance at the sea surface. The role of dust-induced sea surface temperature (SST) responses in simulations of the climatic effect of dust is examined by using a general circulation model with online simulation of mineral dust and a coupled mixed-layer ocean model. Both the longwave and shortwave radiative effects of mineral dust aerosol are considered in climate simulations. The SST responses are found to be very influential on simulated dust-induced climate change, especially when climate simulations consider the two-way dust-climate coupling to account for the feedbacks. With prescribed SSTs and dust concentrations, we obtain an increase of 0.02 K in the global and annual mean surface air temperature (SAT) in response to dust radiative effects. In contrast, when SSTs are allowed to respond to radiative forcing of dust in the presence of the dust cycle-climate interactions, we obtain a global and annual mean cooling of 0.09 K in SAT by dust. The extra cooling simulated with the SST responses can be attributed to the following two factors: (1) The negative net (shortwave plus longwave) radiative forcing of dust at the surface reduces SST, which decreases latent heat fluxes and upward transport of water vapor, resulting in less warming in the atmosphere; (2) The positive feedback between SST responses and dust cycle. The dust-induced reductions in SST lead to reductions in precipitation (or wet deposition of dust) and hence increase the global burden of small dust particles. These small particles have strong scattering effects, which enhance the dust cooling at the surface and further reduce SSTs.
Highlights
Mineral dust aerosol is one of the major aerosol species in the atmosphere
The ensemble runs for MXLSST CTRL, MXLSST fixed dust (FD), and MXLSST coupled dust (CD) are integrated for 50 years, respectively, with the first 20 model years used as the spin-up period
The role of dust-induced sea surface temperature (SST) responses in simulations of the climatic effect of dust is investigated by using a general circulation model (GCM) coupled with a mixed layer ocean model
Summary
While dust aerosol influences the Earth’s energy balance through scattering and absorbing shortwave (SW) and longwave (LW) radiation (Carlson and Benjamin, 1980; Sokolik and Toon, 1996), dust-induced changes in meteorological parameters can feed back into dust cycle by altering emissions, transport, and deposition of dust (Miller et al, 2004a; Heinold et al, 2007). Such dust-climate interactions have been found to be important for simulations of dust-induced climate change (Yue et al, 2010).
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