Work

Convectively Coupled Equatorial Waves in a Global Storm‐Resolving Model

Year: 2026

Type: article

Abstract: We show how reducing the fall speeds of rain and ice leads to reduced biases of Convectively Coupled Equatorial Waves (CCEWs) in convection‐resolving configurations of the Icosahedral Non‐hydrostatic Model (ICON). In particular, reducing the fall speeds of rain and ice leads to stronger activity over the wavenumbers and frequencies associated with convectively coupled Kelvin waves, inertio‐gravity waves, mixed Rossby‐gravity waves, equatorial Rossby waves, and the Madden‐Julian oscillation, and to weaker activity of tropical depressions. The changes in CCEW activity are mediated by changes in the frequency of mesoscale convection profiles. Reducing the fall speeds increases the frequency of bottom‐heavy and top‐heavy mesoscale convection profiles and decreases the frequency of mid‐heavy mesoscale convection profiles. In turn, changes to the mesoscale convective profiles are reflected in the ability of the model to develop the tilt and top‐heaviness of CCEWs. Reductions in the fall speeds also increase precipitation over the warm pool region, possibly allowing for a stronger equatorial forcing of convectively coupled Kelvin waves. Our findings suggest that the representation of CCEWs within ICON agrees with their observed multiscale structure.

Source: Journal of Advances in Modeling Earth Systems

DOI: 10.1029/2026ms005799