Two-regime model reproduces convective self-aggregation

What the study found: The authors propose a simple piecewise linear model for convective self-aggregation, a process in which deep-convective clouds spontaneously organize into a limited region surrounded by drier, convectively inhibited areas. The model treats each atmospheric column as being in one of two thermodynamic regimes and reproduces aggregated and non-aggregated steady states.
Why the authors say this matters: The findings indicate that a self-aggregated state can be considered as a simple gravity wave with two phases, one convective and one convectively inhibited. The study suggests this representation captures many properties seen in kilometre-resolution models.
What the researchers tested: The researchers built a model based on primitive equations in which the thermodynamics in each of two regimes were linearised. They then compared its behavior with kilometre-resolution simulations of self-aggregation.
What worked and what didn't: The model produced both aggregated and non-aggregated steady states and showed hysteresis, meaning multiple equilibria can exist. It also reproduced similar sensitivity to convective inhibition, domain size, and boundary-layer radiative cooling in the dry region as in kilometre-resolution simulations.
What to keep in mind: The abstract does not describe limitations beyond the simplified, piecewise linear structure of the model, so further caveats are not stated in the available summary.

Key points

• The paper proposes a piecewise linear model of convective self-aggregation.
• The model treats atmospheric columns as either deep convective or convectively inhibited.
• It reproduces aggregated and non-aggregated steady states and hysteresis.
• It shows similar sensitivity to convective inhibition, domain size, and boundary-layer radiative cooling as kilometre-resolution models.
• The authors suggest self-aggregation can be viewed as a simple gravity wave with two phases.