9731393 Chang The weather and climate in the mid-latitudes are affected by the passage of cyclones and anticyclones. These systems are generally associated with waves in the upper troposphere which are organized into well defined regions known as storm tracks. Better understanding how the storm tracks form, how they evolve and what determines their location and intensity may help to advance the accuracy of medium range weather forecasting. Dr. Chang's recent results from data analyses and modeling studies suggest that mid-latitude baroclinic waves in these storm tracks are organized into wave packets which propagate eastward with group velocities much faster than the phase speeds of individual waves. The energy associated with these wave packets may contribute to the formation and development of upper level troughs and surface cyclones. Under this award, the principal investigator will extend his earlier results on the properties of wave packets and examine what role they might play in atmospheric predictability.
