DeFlorio, M. J., D. J. Amaya, A. J. Miller, B. Singh, S. J. Ghan and L. M. Russell, 2017:
Interactions of North African dust with tropical and subtropical Atlantic coupled ocean-atmosphere processes
Journal of Climate, sub judice.
Recent work has suggested that North African dust variability over the tropical
and subtropical North Atlantic can account for a large fraction of decadal
changes in SST anomalies. The response of monthly SST anomalies to dust outbreaks on
interannual and decadal timescales is characterized by comparing two Community Earth System Model
(CESM) simulations with and without interannual variability of dust.
These comparisons show an increase in SST variance in the interactive (interannual dust variability allowed)
run over the tropical and subtropical North Atlantic, suggesting that fluctuations of North African
dust can drive regional changes in SST variability. The leading mode of
coupled SST/wind variability in the tropical Atlantic (the Atlantic Meridional Mode (AMM))
is examined. Although the observed SST spatial pattern associated with the AMM appears as
an out-of-phase cross-hemispheric dipole pattern, latent heat
flux coupling to the surface horizontal wind only occurs in the Northern
Hemisphere. In addition, strong cross-equatorial wind flow normally associated
with an interhemispheric SST gradient is present in the CESM
interactive simulation, but absent in the prescribed simulation. These results
indicate that modeled interannual dust variations influence deep tropical WES dynamics.
Strong positive anomalies of summertime dust burden over
the subtropical North Atlantic are associated with strong negative
values of the coupled SST MCA principal components, indicating that
interannual variability of North African dust changes the spatial loading of summertime SST associated with the AMM.