On the Isotopic Composition of Cold Pools in Radiative‐Convective Equilibrium

Although stable water isotopologues are important tools in the study of the climate system, some of the physical processes that affect them are still imperfectly constrained. In this work, I concentrate on cold pools, essential components of deep convective systems that are arguably one of the least understood features from the water isotopologue perspective. Using a combination of a Lagrangian and an Eulerian framework, I first focus on quantifying how different processes determine the initial water vapor isotopic composition of cold pools. By analyzing the precipitation‐driven downdrafts that give rise to cold pools, I determine that mixing with environmental air has an enriching effect. On the other hand, microphysical processes tend to deplete the downdraft in the initial stages, mostly in the free troposphere, and to enrich it in the final stages, when the downdraft is in the subcloud layer. Then, I consider what processes might influence the isotopic composition of cold pools during their propagation, and I find that surface latent heat fluxes play a much greater role than cold pool entrainment. Finally, I show how water isotopologues could be used to diagnose the origin of water vapor in cold pool moist patches.