Disruptions of ENSO Teleconnections by the MJO

Observational analysis shows that strong Madden Julian Oscillation (MJO) activity significantly weakens the atmospheric branch of El Nino-Southern Oscillation (ENSO) both in the core tropical region and in terms of key continental teleconnections. Given MJO forecasting skill out to a few weeks, this suggests the possibility that information can be added to seasonal forecasts of ENSO by considering the strength of tropical intraseasonal variability.

During periods in which the amplitude of the MJO was strong for November-April 1982-2011, precipitation departures associated with ENSO over the tropical Indo-west Pacific were diminished by nearly 50% during El Nino and 75% during La Nina relative to periods in which the MJO amplitude was weak. For individual seasons, such as 2007-2008 (La Nina) and 2009-2010 (El Nino), where strong central Pacific Ocean sea surface temperature anomalies persisted, the tropical Indo-Pacific ENSO-related precipitation dipole was completely erased for many weeks during which time the MJO-related precipitation signal was strong. Over Asia, the North Pacific Ocean and the United States there were clear disruptions to the pattern and large decreases in the magnitude of ENSO-related teleconnections during strong amplitude MJO periods relative to weak MJO amplitude periods.