Data from: Moist heatwaves intensified by entrainment of dry air that limits deep convection

Moist heatwaves in the tropics and subtropics pose substantial risks to
society, yet the dynamics governing their intensity are not fully
understood. The onset of deep convection arising from hot, moist
near-surface air has been thought to limit the magnitude of moist heat
waves. Here, we use reanalysis data, and output from the Coupled Model
Intercomparison Project Phase 6 and model entrainment perturbation
experiments, to show that entrainment of unsaturated air in the lower-free
troposphere (roughly 1--3 km above the surface) limits deep convection,
thereby allowing much higher near-surface moist heat. Regions with
large-scale subsidence and a dry lower-free troposphere, such as coastal
areas adjacent to hot and arid land, are thus particularly susceptible to
moist heat waves. Even in convective regions such as the northern Indian
Plain, southeast Asia, and interior South America, the lower-free
tropospheric dryness strongly affects the maximum surface wet-bulb
temperature. As the climate warms, the dryness (relative to saturation) of
the lower-free tropospheric air increases; this allows for a larger
increase of extreme moist heat, further elevating the likelihood of moist
heat waves.