WWB involve dynamic-convective-surface interactions over a planetary scale. Here, various aspects of the interactions are displayed. The first aspect of their structure were those noticed over the western Pacific Ocean....strong surface westerly winds. 850 Zonal Winds . An eastwards progression in surface westerly winds is apparent along with an intensification and broadening over the western Pacific Warm Pool.

Upper level wind anomalies, at 100 mb, are easterly over the warm pool but also display anomalies on a large-scale and exhibit an eastwards propagation. The anomalies includes significant modulation of the westerly duct (over the eastern Pacific) where interhemispheric wave propagation can be affected.

Large-scale precipitation anomalies estimated from MSU are shown here. WWB are associated with a leading edge of deep convection. The diabatic heating caused by condensation and the radiative impact of clouds has the net effect of strengthening lateral gradients in heating and thus force atmospheric ascent. The strong heating gradients may be fully responsible for the wind motions associated with the bursts. Also, deep convection acts to stabilize the atmosphere as can be seen next.

The large-scale distribution of latent stability is shown here. Here, the measure used to infer stability is CAPE. For description of various CAPE methods, press here. Large-scale CAPE anomalies suggest that the atmosphere is destabilized prior to the onset of the WWB. That is, large amounts of thermal energy...including both moisture and heat.... are accumulated by the environment. Though they account for only about 1 to 2 degrees in THETA E, they increase CAPE by over 10-20%. The environment is therefore more convectively unstable in the mean and deep convection is favored. It is also apparent that after the passage of the burst (ie : to the west), the atmosphere is stabilized. A strong thermodynamic linkage between the dynamics and convection is therefore suggested, even on a large-scale.

Finally, the large-scale distribution of latent fluxes is discussed. It was propsed by Emanuel (1987) that large surface latent fluxes to the east of the WWB were responsible for its eastwards propagation. Here, we see this is not the case. Fluxes are largest underneath surface westerly winds (the western Pacific from Day -2 to 2) as is deep convection (above). WISHE modes, as they were called, do not appear to adequately address the propagation of disturbances.

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