The Impact of the Madden–Julian Oscillation on High-Latitude Winter Blocking during El Niño–Southern Oscillation Events

AbstractWintertime high-latitude blocking is associated with persistent changes in temperature and precipitation over much of the Northern Hemisphere. Studies have shown that the Madden-Julian Oscillation (MJO), the primary form of intraseasonal tropical variability, significantly modulates the frequency of high-latitude blocking through large-scale Rossby waves that alter the global circulation. However, the characteristics of MJO teleconnections are altered by the El Nino-Southern Oscillation (ENSO), which modifies the global flow on interannual timescales, suggesting that the MJO influence on blocking may depend on ENSO phase.The characteristics of MJO Rossby waves and blocking during ENSO events are examined using composite analysis and a nonlinear baroclinic model. The ENSO phase-dependent teleconnection patterns are found to significantly impact Pacific and Atlantic high-latitude blocking. During El Nino, a significant persistent increase in Pacific and Atlantic blocking follows MJO RMM phase 7, cha...