Deciphering the Prevalence of Warm‐Wet Extremes in Ice‐Covered Zones

Abstract

Abstract Compound warm extremes exert profound impacts on environment, health, and socioeconomics. Yang et al. (2024) indicated a shift or transition from warm‐dry extremes (WDEs), common in non‐ice‐covered areas, to warm‐wet extremes (WWEs) in ice‐covered zones. Utilizing ERA5 reanalysis data, this study determined the duration and frequency of WDEs and WWEs across ice‐covered and non‐ice‐covered regions. A comprehensive analysis uncovers the physical mechanisms responsible for the paradigm differences and attributes them to the weakening of land‐atmosphere interaction caused by ice‐cover, which inhibits soil moisture feedback and reduces the intensity and duration of warm events in ice‐covered areas. Both WDEs and WWEs are associated with high‐pressure systems (HPs). WDEs, situated directly beneath HPs, intensify due to adiabatic warming from subsidence motions. Conversely, WWEs, located beneath the poleward fringes of HPs, emerge from advective warming and moistening associated with poleward intrusions of warm‐moist air.