EGU25-13965, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-13965
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Reduction of the estimated gravity wave momentum flux by concurrent wave packets
Brian Green1, Aditi Sheshadri1, and Aurelien Podglajen2
Brian Green et al.
  • 1Stanford University, Earth System Science, United States of America
  • 2Laboratoire de Météorologie Dynamique/Institut Pierre Simon Laplace, École Normale Supérieure- Paris Sciences et Lettres Université, École Polytechnique- Institut Polytechnique de Paris, Sorbonne Université, CNRS, Paris, France

Starting with simulations of idealized linear gravity wave packets, we show how interference between multiple gravity wave packets can result in an underestimation of their combined vertical flux of horizontal momentum by up to 50%. The two key ingredients for this result are the packets must have similar enough frequencies that their projections onto the time-frequency domain overlap, and that they propagate in different horizontal directions. This combination results in errors in the estimated phase relationship between wave-induced horizontal and vertical wind anomalies and reduces the estimate of the magnitude of the packets’ combined momentum flux. Because this mechanism doesn’t affect estimates of the power of a single variable, we propose using a scaling relationship derived from the theory of linear gravity waves in a Boussinesq atmosphere to estimate the momentum flux from the wave energy. We then apply this relationship to data from three lower stratosphere super-pressure balloon campaigns: Loon, Concordiasi, and Strateole-2. We find that both ingredients for wave interference are typically present in the data, evidence that our scaling relationship is appropriate for these calculations, and that momentum fluxes may be underestimated by even more than our simulations of idealized waves suggest. Our results show that the upward flux of horizontal momentum from the troposphere into the stratosphere by gravity waves is likely higher than previously thought, and that care must be taken analyzing output from models that resolve part of the gravity wave spectrum.

How to cite: Green, B., Sheshadri, A., and Podglajen, A.: Reduction of the estimated gravity wave momentum flux by concurrent wave packets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13965, https://doi.org/10.5194/egusphere-egu25-13965, 2025.