A stability-landscape view of cloud states and transitions

Warm boundary-layer clouds, namely shallow cumulus, and stratocumulus, cover major parts of the tropical and subtropical oceans. Capturing their response to anthropogenic perturbations of aerosols and large-scale cloud-controlling parameters is a key challenge for climate projections. Such a response of a cloud field can on the one hand consist of gradual changes in cloud characteristics. The response of stratocumulus to aerosols, e.g., may even be muted because cloud adjustments partially compensate an initial effect, a feature known as buffering or resilience. On the other hand, cloud fields may respond by rapid transitions, e.g., between the stratocumulus and shallow-cumulus regimes, or between the closed- and open-cell morphological states within the stratocumulus regime.

We will conceptualize this behavior from the perspective of quasi-potential landscapes. Such landscapes capture the stability of cloud states to perturbations, or their instability to transitions, respectively. For stratocumulus, we will describe the closed- and open-cell states and their transitions, including to the shallow-cumulus regime. For the latter, "sugar", "gravel", "fish" and "flower" patterns have recently been identified as characteristic mesoscale organization types. This raises the question if these patterns are analogous to the stratocumulus morphologies. We will explore how to address this question in view of the stability-landscape framework, and which generalizations of the stratocumulus picture may be required.