Speaker: Carlos Ordaz (CUNY)
Topic: Predicting Changes in Precipitation Distributions in Radiative-Convective Equilibrium using Clausius-Clapeyron Scaling and a Decrease Mode

Precipitation frequency and intensity changes are critical yet uncertain under climate change. Two physical constraints govern these changes: Clausius-Clapeyron (CC scaling at about 7% per Kelvin) which tends to be associated with extremes, and radiative cooling, which modulates the scaling of the mean precipitation rate at 2-4% per Kelvin. We show these laws quantitatively constrain the full precipitation distribution's response in a perturbed state. Using cloud-resolving models (CRMs) in Radiative-Convective Equilibrium (RCE), CC scaling and the mean precipitation change together suggest a reduced rain event frequency. A "decrease mode," enforcing the radiative constraint, reduces the distribution's amplitude by 3 to 4% per Kelvin, quantifying increased sparseness of precipitation events. This mode also corresponds to declines in convective rain area and mass fluxes. Thus, combining these constraints establishes a unified physical basis for fewer rain events, offering a pathway to anticipate global water cycle changes.