A comparison of western Pacific ET-induced Rossby wave packets with those associated with midlatitude systems

Previous studies have documented instances where the extratropical transition of tropical cyclones leads to an amplification of the midlatitude flow and a Rossby wave packet that propagates downstream faster than the remnant cyclone itself. This Rossby wave packet is often associated with high-impact weather events, such as snowstorms, record high temperatures, etc., and potentially decreased predictability over much of a hemisphere. Therefore, it is worthwhile to understand the character of these packets and aspects of their generation that may be unique to ET events. Previous studies have focused on the Rossby waves generated by individual events, but a comprehensive comparison of packets generated by ET events to those associated with wintertime midlatitude cyclones is lacking.

In order to determine aspects that are peculiar to ET wave packets, this study compares the Rossby wave properties associated with western Pacific ET events to wintertime midlatitude cyclones in the same basin by compositing Climate Forecast System Reanalysis (CFSR) reanalysis data from 1979-2009. Preliminary results indicate that the ET-induced wave packets appear to travel further downstream and have longer horizontal wavelengths relative to wintertime cyclones. The implications of this work will also be discussed.