Cross-Scale Kinetic Energy Pathways in the Atmosphere

Earth's atmosphere is a complex, multi-scale dynamical system that continuously exchanges energy across a broad range of spatial and temporal scales. Analyzing the nonlinear transfer of kinetic energy (KE) that occurs across scales ranging from planetary circulation patterns that shape the climate to smaller-scale systems that underpin daily weather, is central to understanding and predicting the dynamical evolution of Earth's atmosphere. This nonlinear coupling across the vast range of atmospheric scales is a primary factor limiting weather forecasts over long timescales. Scale-by-scale analysis has traditionally relied on spectral methods that are inherently global, such as spherical harmonics, which cannot provide spatial information or geographical maps of processes at different scales. This work employs a recently developed commutative coarse-graining framework on the sphere to investigate the KE transfer between planetary-scale circulation patterns and synoptic- to mesoscale motions by presenting geographic maps of the KE cascade for the first time.