Western Hemisphere Extratropical Circulation and the Indian Ocean MJO

MJO convection in the tropics is intrinsically coupled with the global atmospheric circulation. In response to convection, extratropical planetary waves and Kelvin waves circumnavigate the globe. Intraseasonal and synoptic Rossby waves are guided back into the tropics of the Western Hemisphere on background westerly wind. These waves modulate momentum in the equatorial waveguide. This presentation will show momentum budget analysis of observations and reanalysis data that demonstrates the dynamical source of upper tropospheric easterly wind anomalies on the equator that develop over the Western Hemisphere in advance of most high amplitude active convective phases of the MJO over the Indian Ocean.