Seo, H., A. J. Miller and J. R Norris, 2016:
Eddy-wind interaction in the California Current System: Dynamics and impacts
Journal of Physical Oceanography,
46, 439-459.
Abstract.
The summertime California Current System (CCS) is characterized by energetic mesoscale
eddies, whose sea surface temperature (SST) and surface current can significantly modify the
wind stress and Ekman pumping. Relative importance of the eddy-wind interactions via SST and
surface current in the CCS is examined using a high-resolution (7 km) regional coupled model
with a novel coupling approach to isolate the small-scale air-sea coupling by SST and surface
current. Results show that, when the eddy-induced surface current is allowed to modify the wind
stress, the spatially-averaged surface eddy kinetic energy (EKE) is reduced by 42%, and this is
primarily due to enhanced surface eddy drag and reduced wind energy transfer. In contrast, the
eddy-induced SST-wind coupling has no significant impact on the EKE. Furthermore,
eddy-induced SST and surface current modify the Ekman pumping via their crosswind SST gradient
and surface vorticity gradient, respectively. The resultant magnitudes of the Ekman pumping
velocity are comparable, but the implied feedback effects on the eddy statistics are different. The
surface current-induced Ekman pumping mainly attenuates the amplitude of cyclonic and
anticyclonic eddies, acting to reduce the eddy activity, while the SST-induced Ekman pumping
primarily affects the propagation. Time-mean rectified change in SST is determined by the
altered offshore temperature advection by the mean and eddy currents, but magnitude of the
mean SST change is greater with the eddy-induced current effect. The demonstrated remarkably
strong dynamical response in the CCS system to the eddy-induced current-wind coupling
indicates that eddy-induced current should play an important role in the regional coupled ocean
atmosphere system.
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