MJO and its relationship to ENSO

In this study, we detected the spatial and temporal characteristics of Madden-Julian Oscillation (MJO) using zonal winds at the surface and outgoing long-wave radiation (OLR) from the NCEP-NCAR (U. S. National Center of Environmental Prediction-National Center for Atmospheric Research) reanalysis product from 1981-2003. The results show that MJO activity, represented by these two variables, has large variances around 10 degrees off the equator and over the near-equatorial western Pacific. One central issue addressed in this study is MJO-ENSO (El Nino and Southern Oscillation) relationship. It has been found that there exists a statistically significant relationship between MJO in spring-summer and ENSO in autumn-winter. The relationship of MJO-ENSO is nonlinear in nature and has a decadal variation. A much stronger statistical relationship of MJO-ENSO was found in the 1990s as compared to that in the 1980s. These findings were further verified using ECMWF (European Center for Medium-Range Weather Forecasts) reanalysis product. The potential mechanisms responsible for MJO-ENSO relationship are also discussed.