Size of the Atmospheric Blocking Events: Scaling Law and Response to Climate Change

Understanding the response of atmospheric blocking events to climate change has been of great interest in recent years. However, potential changes in the blocking area (size), which can affect the spatiotemporal characteristics of the resulting extreme events, have not received much attention. Using two large‐ensemble, fully coupled general circulation model (GCM) simulations, we show that the size of blocking events increases with climate change, particularly in the Northern Hemisphere (by as much as 17%). Using a two‐layer quasi‐geostrophic model and a dimensional analysis technique, we derive a scaling law for the size of blocking events, which shows that area mostly scales with width of the jet times the Kuo scale (i.e., the length of stationary Rossby waves). The scaling law is validated in a range of idealized GCM simulations. Predictions of this scaling law agree well with changes in blocking events' size under climate change in fully coupled GCMs in winters but not in summers. Key Points Size of blocking events robustly increases with climate change in most regions in two sets of large‐ensemble fully coupled GCM simulations A scaling law for blocking area is derived in a QG model using the Buckingham‐π theorem and is verified using idealized GCM simulations The scaling law is area ~ width of the jet × Kuo scale and partially explains the projected changes in the fully coupled GCM simulations