Abstract North Pacific and North Atlantic summer subtropical highs (NPSH and NASH) strongly influence regional climates, but their responses to glacial conditions remain unclear. This study examines their changes during the Last Glacial Maximum compared to the preindustrial period, utilizing 14 models from Coupled Model Intercomparison Project Phases 5 and 6. The models consistently reveal a weakened NPSH and a strengthened NASH. NASH strengthening is driven by diabatic cooling due to suppressed atmospheric convection over ice‐covered North America and the North Atlantic. NPSH weakening arises from both a dynamical adjustment to an enhanced upper‐level westerly jet and increased latent heat release over the northern tropical Pacific, induced by a northward‐shifted and intensified rising branch of the local Hadley circulation over the central–eastern tropical Pacific. These results underscore distinct mechanisms governing subtropical high variations under glacial conditions, in contrast to those projected under future warming scenarios, and provide a plausible explanation for geological records around both basins.
Liu et al. (Thu,) studied this question.