Global Circulation Variability Associated with MJO Phase Speed

Differences in the Madden–Julian oscillation (MJO) phase speed help explain some of the variability in the global circulation pattern. A mechanism that utilizes these distinctive circulation signals is applied to help explain MJO variability associated with different phase speeds. Wavelet filter analysis is first used to compute regression models of MJO signals at different phase speeds, isolating the associated patterns in outgoing longwave radiation (OLR), geopotential height, and horizontal wind. Both Fourier filtered and wavelet filtered data are also used to reconstruct the background wind proximate the active phase MJO. One result using this reconstructed background wind is that equatorial easterly winds downstream of the 2 m s^–1 MJO in phases 2 and 3 are notably faster than the higher phase speed, 8 m s^–1 MJO. Monte Carlo analysis is used to assess statistical significance of these differences in background wind. This work provides motivation and groundwork for further investigation into how the global circulation may impact MJO propagation and superstructure.