A dynamical-systems perspective on aerosol-stratocumulus interactions

The evolution of stratocumulus cloud decks is governed by three timescales: the large-scale evolution of the boundary layer, the mesoscale evolution of liquid water path and cloud fraction, and the microscale processes of cloud microphysics and aerosol-cloud interactions. Our quantitative understanding of aerosol-cloud-climate cooling is especially challenged by the mesoscale response of stratocumulus decks to aerosol perturbations. This response can on the one hand be muted because cloud adjustments partially compensate an initial effect, a feature known as buffering or resilience. On the other hand, stratocumulus may respond by drastic transitions between the closed- and open-cell morphologies or into the shallow-cumulus regime. We will conceptualize this behavior from the perspective of dynamical-systems theory. Our description can be visualized as a quasi-potential landscape. This landscape quantifies the resilience of mesoscale cloud states to perturbations and charts transition pathways. Building on this, we will explore implications for the quantification of adjustments, especially in cloud fraction.