Monotonic Increase of Extreme Precipitation Intensity With Temperature When Controlled for Saturation Deficit

Past studies based on univariate scaling analyses at the weather time scale documented a negative scaling of extreme precipitation intensity (EPI), which prevents EPI extrapolation from past climate. Here we present a bivariate scaling analysis and show that, contrary to the univariate scaling results, EPI monotonically increases with temperature and shows no negative scaling when controlled for saturation deficit. The observed EPI-temperature relationship in saturated atmosphere is surprisingly similar among different regions and closely follows the Clausius-Clapeyron scaling; climate models produce greater regional dependence of the scaling relationship with a wide range of scaling rate. For extratropical regions, the model-simulated EPI-temperature relationship under saturation shows a past-to-future continuity, which could potentially support extrapolation to a warmer climate. The scaling at saturation bridges the EPI-temperature relationship between weather and climate time scales and may enable potential prediction of future precipitation extremes via extrapolation from past observations.