Scaling of precipitation extremes with surface temperature in western Canada: Understanding the control factors using a convection‐permitting climate model

Abstract The Clausius–Clapeyron (CC) relationship can shed light on understanding how precipitation extremes may change in a warming climate. We evaluated relationships between hourly extreme precipitation and surface temperature using observed and simulated datasets and found the convection‐permitting climate model is able to capture the observed relationships between precipitation extremes and temperature (PT scaling) in western Canada. In the current climate, the intensity of extreme precipitation increases with temperature approximately at the CC scale in the Prairie, North, and Mountain regions, whereas a clear sub‐CC scale can be seen in the Coast region. All four regions show a negative scaling rate at warm temperature bins. In the future climate, precipitation extremes in each region get intensified with warming at a larger scale rate than that in the current climate. A super‐CC and even double‐CC rate can be seen in the Coast, Prairie, and North regions. A similar scaling method has been applied for the corresponding column integrated water vapour, vertical velocity, and the convective available potential energy. We found the PT scaling pattern is physically governed by the ascending velocity of air and the amount of atmospheric water vapour. Approximately 99% of the variation of precipitation extremes can be explained by the vertical velocity and 95% by the precipitable water for the current climate in western Canada. In the future, more than 97% of the variation of precipitation extremes can be explained by the precipitable water and more than 99% by the vertical velocity.