Tug-Of-War on Idealized Midlatitude Cyclones Between Radiative Heating From Low-Level and High-Level Clouds

We present baroclinic life-cycle simulations with two versions of the atmosphere model ICON to understand how cloud-radiative heating and cooling affect an idealized midlatitude cyclone. Both versions simulate the same cyclone when run without radiation, but disagree when cloud-radiation-interaction is taken into account. The radiative effects of clouds weaken the cyclone in ICON2.1 but strengthen it in ICON2.6. We attribute the disagreement to low-level clouds, which in ICON2.1 are more abundant and show stronger radiative cooling of the boundary layer. We argue that radiative cooling from low-level cloud tops weakens the cyclone by increasing boundary-layer static stability, and that radiative cooling from high-level cloud tops strengthens the cyclone by decreasing static stability in the upper troposphere and sharpening the tropopause. Our results indicate that clouds and the vertical distribution of their radiative heating and cooling can influence the dynamics of midlatitude cyclones.