A Lagrangian Approach to Storm Tracks

The storm tracks are traditionally defined in either one of the following ways: using an Eulerian approach, as regions of enhanced transient eddy kinetic energy (EKE), obtained using a bandpass time filter with a typical 3–10-day period; or alternatively, using an ensemble of Lagrangian feature tracking of the storms. The latter identifies the storms, tracks them Lagrangially and then analyzes their statistical distributions. The feature-tracking technique gives information about what type of systems, cyclones or anticyclones, compose the statistics of the eddy activity. We use the Lagrangian approach to study mechanisms that control the formation, intensity, and spatial distribution of the storm tracks. This was found useful for explaining the poleward motions of cyclones, the poleward deflection of the localized storm tracks in the northern hemisphere, and the projected poleward shift of the storm tracks under climate change.