The recurrence of atmospheric blocking

Wow, a busy month. Ka Ying Ho, a PhD student with Lei Wang at Purdue University, just submitted an investigation into the return period distribution of atmospheric blocking to the Journal of Climate! It is joint work with Yi Ming at Boston College.

Atmospheric blocking is a large-scale weather pattern in the midlatitudes associated with various types of extreme events, such as heat waves, droughts, and cold spells. Understanding its regularity in time can help us better predict its onset and understand the forecast limit of blocking. Using a hierarchy of simple red-noise models, we identify the key parameters that contribute to the recurrence pattern of blocking, specifically, the climatological onset frequency and the temporal correlation of Rossby waves, which shape the return period distribution and timescale. These insights also help interpret changes in the pattern of recurrence and forecast challenges in a warmer climate from the CESM1 simulations, where a decrease in blocking events increases the uncertainty of their recurrence.