The Role of Rossby Waves in Polar Atmospheric Dynamics

Abstract:

The weather and climate of Earth's polar regions is increasingly important as the planet warms, as evidenced by extreme events impacting both high and lower latitudes. Atmospheric circulation is critical in many of these, such as high-latitude heatwaves, persistent cyclones and annular mode anomalies. Rossby waves are often invoked in mechanistic explanations of such events, but how relevant really are Rossby waves at high latitudes? After all, these waves rely on the meridional gradient of planetary vorticity, which is very weak in the polar regions. Here we review some of the fundamentals of Rossby waves and present some diagnostics exploring their role in polar dynamics. We suggest that Rossby waves are indeed a key building block of polar climate, although less so than they are in the mid-latitudes. Furthermore, the characteristics of these waves differ somewhat from the more familiar mid-latitude waves, and this might help in understanding some of the recent extreme events.