| dc.description.abstract | Recent studies indicate that coupled general circulation models
(GCM) display mixed success in simulating the properties of
the El Ni\~{n}o/Southern Oscillation (ENSO). Specifically, aggregate
runs of various GCMs typically show spatial and temporal disparities
compared to observations. We turn to the Zebiak-Cane model of
intermediate complexity for the tropical Pacific ocean to study
the response of the sea surface temperature (SST) and inter-annual
variability of ENSO under different wind stress conditions.
Spatial variation is modeled after the meridional structure of the
zonal wind stress based on TAO/TRITON measurements, and furthermore
on reconstructed Pliocene conditions from the
HadCM3 PlioMIP Exp 2 wind data. Temporal variations are
introduced with a simple seasonal cycle. Among all conditions simulated,
only very weak trade winds result in a "permanent" \EN with weak
SST gradients and no variability. A cold tongue (CT) structure is
always present when the wind is above a minimum critical value, although
the oscillations vanish if the wind crosses a threshold maximum value.
Apart from these extremes, periods of $3\sim4$ years are found with
$\Delta SST$ amplitudes of 5\degrees $\sim$ 9\degrees. | |
