The Evolution and Behavior of High-Amplitude Extratropical Wave Patterns Associated with the Madden-Julian Oscillation and Equatorial Rossby Waves

High-impact weather events associated with high-amplitude extratropical Rossby wave patterns can influence energy demand, agricultural production, and risk management decisions. These wave patterns are often associated with responses in the global circulation to organized large-scale convection accompanying the Madden-Julian Oscillation (MJO) and/or other equatorial wave modes. Analyzing these wave patterns with respect to the MJO and other equatorial wave modes can give us clues about their origins, evolution, and dynamics. In turn, by understanding how these wave patterns develop and behave, we can improve our ability to predict these patterns well ahead of time.

We examine a high-amplitude extratropical Rossby wave pattern that exists on MJO time scales (30-100 days) over the central North Pacific Ocean. This wave pattern is first identified by compositing 300-hPa geopotential height and wind anomalies associated with a simultaneous assessment of the MJO in phase 4 of the Real-time Multivariate MJO (RMM) PCs and equatorial Rossby (ER) wave crests at 157.5 degrees east during boreal winter. A list of simultaneous MJO and ER wave events is then compiled to identify individual events, and several events are analyzed to shed light on the origins, evolution, and dynamics of the wave pattern in question.