Abstract
[There is a lack of agreement on the sign and magnitude of the effect
of dust-radiative forcing on African easterly waves (AEWs) among past
studies. The uncertainty in the dust-radiative forcing associated with
the estimation of shortwave absorption is a leading cause of
disagreement in the literature. The inability of models to represent
various dust–AEW interaction pathways also leads to uncertainty among
modeling studies. The present study investigates the sensitivity of AEWs
to the observed variability in dust shortwave absorption using a
high-resolution atmospheric general circulation model. Global
simulations are conducted at a spatial resolution of about 25 km to
simulate AEWs and associated circulation features adequately well. The
results reveal that AEWs are highly sensitive to dust shortwave
absorption. In addition, the AEW activity intensifies and broadens the
wave track with a southward shift in response to dust shortwave
absorption. There is approximately a 25 \% change in
eddy kinetic energy (EKE) associated with AEWs for the range of dust
shortwave absorption used. The 6-9–day waves are more sensitive to dust
shortwave absorption than the 3-5–day waves, where the response in the
former has a stark land–sea contrast. The sensitivity of AEW to dust
heating stems from a combination of the response from various energy
conversions. Although baroclinic energy conversion is the leading term
in the energy cycle, the responses to dust shortwave heating in
barotropic and generation terms are comparable to those in baroclinic
conversion.]