The role of inertia-gravity waves in the atmospheric energy spectrum: insights from global storm-resolving simulations
Authors:
Yanmichel Morfa Avalos
Abstract:
This dissertation examines the kinetic energy spectra of atmospheric motions, focusing on both horizontal and vertical components using global storm-resolving simulations. Horizontal kinetic energy follows canonical power laws, with a steep 𝜅−3 decline at synoptic scales (∼10,000–1,000 km) driven by quasigeostrophic turbulence, and a shallower 𝜅−5/3 regime at mesoscales (<600 km), though the origins of this mesoscale spectrum remain debated. Vertical kinetic energy spectra, less studied due to measurement challenges, exhibit nearly white spectra with peaks at synoptic and mesoscale ranges, attributed primarily to inertia-gravity wave (IGW) fluctuations.
The dissertation shows that vertical kinetic energy spectra can be largely explained by horizontal winds associated with IGWs, with hydrostatic IGW theory accurately predicting spectral slopes across scales. Differences in mesoscale vertical velocity spectra are linked to IGW properties. Further investigation into mesoscale energy transfer reveals distinct dynamics between the troposphere and lower stratosphere: the stratosphere is energized by vertically propagating IGWs, while mesoscale energy in the troposphere arises from spectral transfers across scales, influenced by interactions between IGWs and balanced flow. These findings challenge prior theories of mesoscale energy transfer dominated by weakly nonlinear IGW interactions.