Enhanced Blocking Frequencies in Very-High Resolution Idealized Climate Model Simulations

Abstract

Atmospheric blocking is a key dynamical phenomenon in the mid- and high latitudes, able to drive day-to-day weather changes and meteorological extremes such as heatwaves, droughts and cold waves. Current global circulation models struggle to fully capture observed blocking frequencies, likely because of their coarse horizontal resolution. Here we use convection permitting, nested idealized model simulations for quantifying changes in blocking frequency and Rossby wave breaking compared to a coarser resolution reference. We find an increase in blocking frequency poleward and downstream of the area with increased resolution, while the exact regions depend on the blocking index. These changes are probably due to a more accurate representation of small-scale processes such as diabatic heating, which affect Rossby wave breaking and blocking formation downstream. Our results thus suggest an improved representation of blocking in the next generation of high-resolution global climate models.