Impact of Dust Radiative Forcing upon Climate - Mineral Dust: A Key Player in the Earth System - page 329

a

b

Fig. 13.4 Anomalous atmospheric ( red ) and ocean ( blue ) temperature during the first ( a )20days
and ( b ) 2 years after the onset of forcing in a simple single-column model. The forcing consists of
a succession of weekly dust outbreaks where the magnitude of aerosol radiative forcing increases
rapidly for a day before diminishing more gradually with a 1 day e-folding time. The time averaged
forcing equals 10 Wm 2 at the surface. The dotted line shows the ocean

temperature response in the absence of coupling by the surface turbulent and radiative fluxes, so
that the ocean temperature responds only to the surface forcing (Reproduced from Miller ( 2012 ).
Copyright (2012) with permission from the American Meteorological Society)

5 Wm 2 at TOA and

reaching equilibrium when the temperature increment due to a new outbreak is
balanced by the recovery following an earlier outbreak (Fig. 13.4 b). Although the
atmosphere warms temporarily after each outbreak, it cools on a longer time scale
due to the diminished heat import from the cooling ocean. The dotted line in
Fig. 13.4 b represents the ocean temperature change that would result solely from
the surface forcing. Its divergence from the full response indicates the importance
of coupling between the atmosphere and ocean. At equilibrium, the temperature
perturbation is linearly proportional to the forcing at TOA, but is only weakly
dependent upon the surface forcing, in contrast to the immediate continental
response in Fig. 13.3 b.