The consistency of MJO teleconnection patterns on interannual timescales

Tropical heating associated with the Madden-Julian oscillation (MJO) excites stationary Rossby waves that propagate into the Northern Hemisphere midlatitudes, which provide a major source of subseasonal to seasonal (S2S) prediction skill. Highly consistent MJO teleconnection patterns from one event to the next occur in association with certain MJO phases. However, previous research has not examined how interannual variability in the form of El Niño-Southern Oscillation modulates this pattern consistency. This presentation describes work using reanalysis fields, ensemble simulations of a linear baroclinic model, and a ray tracing algorithm to document how and why interannual variability modulates the pattern consistency of boreal winter MJO teleconnections. In particular, we show that MJO teleconnection pattern consistency is reduced during El Niño warm events, which suggests a diminished potential to leverage the MJO for S2S prediction during these conditions. Both the structure of MJO heating anomalies in the tropics and basic state flow are shown to be less conducive for producing a consistent midlatitude teleconnection during warm events than other winters.