Compound Climate Events and Extremes in the Midlatitudes: Dynamics, Simulation, and Statistical Characterization

The balance between temperature and moisture contributions to hot–humid extremes results from processes that affect water vapor and atmospheric stability—for example, surface radiative heating, evapotranspiration, and deep convection. A comprehensive evaluation of current and future hot–humid extremes thus requires both full-complexity global climate models and high-resolution regional simulations, able to resolve small-scale processes such as land surface evaporation. The focus next shifted to the role of moist oceanic air masses—and more broadly storm-track activity—in favoring compound coastal flooding from co-occurring extreme precipitation and storm surge. The simultaneous occurrence of anticyclonic planetary wave breaking to the south of the North Atlantic jet stream and cyclonic wave breaking to the north of the jet stream leads to a very zonal and intense large-scale flow.