Intensification of convective extremes driven by cloud-cloud interaction

TL;DR

This study shows that cloud-cloud interactions significantly intensify convective precipitation extremes in a warming climate, emphasizing the importance of including these dynamics in climate models.

Contribution

It reveals that convective cloud interactions, rather than thermodynamic forcing alone, drive the intensification of precipitation extremes in climate change.

Findings

Increased boundary interactions lead to higher precipitation extremes.

Convective events without interaction are unaffected by temperature changes.

Self-organization enhances convective intensity independently of temperature.

Abstract

In a changing climate, a key role may be played by the response of convective-type cloud and precipitation to temperature changes. Yet, it is unclear if precipitation intensities will increase mainly due to modified thermodynamic forcing or due to stronger convective dynamics. In gradual self-organization, convective events produce highest intensities late in the day. Tracking rain cells throughout their life cycles, we find that interacting events respond strongly to changes in boundary conditions. Conversely, events without interaction remain unaffected. Increased surface temperature indeed leads to more interaction and higher precipitation extremes. However, a similar intensification occurs when leaving temperature unchanged but simply granting more time for self-organization.Our study implies that the convective field as a whole acquires a memory of past precipitation and inter-cloud dynamics, driving extremes. Our results implicate that the dynamical interaction between convective clouds must be incorporated in global climate models to describe convective extremes and the diurnal cycle more realistically.