Aeolus 2.0's Thermal Rotating Shallow Water Model: A New Paradigm for Simulating Extreme Heatwaves, Westerly Jet Intensification, and More

ABSTRACT In this study, we demonstrate the dynamical core and applicability of Aeolus 2.0, a moist-convective Thermal Rotating Shallow Water (mcTRSW) model of intermediate complexity, along with its novel bulk aerodynamic and moist-convective schemes, in capturing the effects of increased radiative forcing on zonal winds and heatwaves. Simulations reveal seasonal patterns in zonal wind, temperature, and energy anomalies under increased radiative forcing during the summer solstice, winter solstice, and equinoxes. Increased radiative forcing enhances mid-latitudinal temperatures during the summer solstice in the Northern Hemisphere and the winter solstice in the Southern Hemisphere, leading to increased zonal wind velocity in the affected hemisphere, especially in the subtropics, while decreasing it in the opposite hemisphere. This thermal forcing also reduces the zonal wind velocity of polar cyclones in the hemisphere experiencing increased radiative forcing. During the autumn equinox, zonal wind velocity diminishes in the Southern Hemisphere, while a similar reduction occurs in the Northern Hemisphere during the spring equinox. Heightened meridional gradients significantly influence the poleward displacement of atmospheric circulation, particularly during the summer (northward) and winter (southward) solstices. Poleward eddy heat fluxes persist across hemispheres, indicating a consistent response to external heating. Increasedradiative forcing during the summer and winter solstices amplifies prolonged heatwaves across land and ocean, exceeding impacts observed during the spring and autumn equinoxes.