Changing duration and spatial extent of midlatitude precipitation extremes across different climates

Precipitation extremes intensify with climate warming in observations and simulations, but changes in their duration or spatial extent are not well understood. Here the duration and zonal length of midlatitude precipitation extremes are quantified in climate model simulations. Most comprehensive climate models project a decrease in duration over the 21st century, although the magnitude of the decrease with warming is less than 1%K-1 in the multimodel mean. An advective time scale based on the mean zonal wind is shown to be linked to the duration in terms of spatial distribution, intermodel differences, and response to climate change. In simulations with an idealized climate model, a stronger meridional temperature gradient decreases the duration despite increases in the zonal length, and this is explained using the thermal wind relation and the Rossby deformation radius. However, the response of the zonal length to increasing mean temperature requires further study.