Large Scale Dynamics and MJO Forcing of ENSO Variability
Michael J. McPhaden, Xuebin Zhang, Harry H. Hendon, and
Matthew C. Wheeler
2006: Geophy. Res. Lett., 33, L16702, doi:10.1029/2006GL026786.
Abstract
A simple two-predictor regression model is developed to estimate
the relative influence of large-scale low frequency ocean-atmosphere
dynamics and high frequency atmospheric forcing on peak sea surface
temperature (SST) anomalies associated with El Niņo/Southern
Oscillation (ENSO) variations for the period 1980-2005. One
predictor is equatorial warm water volume (WWV), which is an index
for the role that upper ocean heat content plays in regulating ENSO
variability. The other predictor characterizes high frequency
atmospheric forcing in the western Pacific linked to the Madden-Julian
Oscillation (MJO). The two-predictor model accounts for about 60-65%
of peak Nino3.4 SST anomaly variance at 2-3 season lead times and
suggests about equal influence (on average) of low frequency dynamical
processes and the MJO on peak ENSO SST anomalies over the past 25
years. The implications of these results for ENSO prediction are discussed.