A variety perspectives and approaches coexist in the study of storm tracks, their governing mechanisms and their response to climate change. The climate/general circulation perspective views the storm tracks as a statistical ensemble of waves and eddies interacting with the mean flow, while the weather/synoptic perspective focuses on the behavior of individual storms and sub-storm structures. The former perspective typically identifies storm tracks using Eulerian diagnostics, while the latter naturally uses feature-tracking methods, resulting in different pictures of the storm tracks (see figure above). Numerical approaches involve a broad hierarchy of model complexities and initial-value or statistically steady-state simulations.
The aim of this meeting is to bring together scientists representing various communities to (i) explore how insights from their different perspectives may be integrated, and (ii) identify opportunities for testing different mechanistic storylines quantitatively. The meeting will be organized around two broad topics:
1. Storm track position and spatial structure. What controls the latitudinal position and spatial structure of the climatological storm tracks, and how will it change in response to global warming? A poleward shift of the storm tracks is a robust prediction of climate model simulations, but there are currently several different mechanisms to explain this response. How unique are each of these mechanisms and can several of them work simultaneously? What is the relative importance of each mechanism to the real atmosphere? How does the climatological response relate to storm track variability, for example through blocking or wave-mean flow interaction?
2. Storm track intensity. What controls the overall number of cyclones and the distribution of cyclone intensities and lifetimes, and how will these change under global warming? Climate models give ambiguous predictions about these changes; can we develop storylines to explain these varying responses? What are the relative roles of dry dynamics and diabatic heating by moist processes and cloud-radiative feedbacks? What light does the seasonal evolution of storm tracks throw on these questions — for example the midwinter minimum of the Pacific storm track?
Scientific advisory group:
Isaac Held, GFDL
John Methven, University of Reading
Gwendal Rivière, ENS/LMD
Tiffany Shaw, University of Chicago
Heini Wernli, ETH Zürich