Transition from geostrophic turbulence to inertia-gravity waves in the atmospheric energy spectrum

Jörn Callies, Raffaele Ferrari, Oliver Bühler

Research output: Contribution to journalArticle

Abstract

Midlatitude fluctuations of the atmospheric winds on scales of thousands of kilometers, the most energetic of such fluctuations, are strongly constrained by the Earth's rotation and the atmosphere's stratification. As a result of these constraints, the flow is quasi-2D and energy is trapped at large scales-nonlinear turbulent interactions transfer energy to larger scales, but not to smaller scales. Aircraft observations of wind and temperature near the tropopause indicate that fluctuations at horizontal scales smaller than about 500 km are more energetic than expected from these quasi-2D dynamics. We present an analysis of the observations that indicates that these smaller-scale motions are due to approximately linear inertia-gravity waves, contrary to recent claims that these scales are strongly turbulent. Specifically, the aircraft velocity and temperature measurements are separated into two components: one due to the quasi-2D dynamics and one due to linear inertia-gravity waves. Quasi-2D dynamics dominate at scales larger than 500 km; inertia-gravity waves dominate at scales smaller than 500 km.

Original languageEnglish (US)
Pages (from-to)17033-17038
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number48
DOIs
StatePublished - Dec 2 2014

Keywords

  • Atmospheric dynamics
  • Geostrophic turbulence
  • Inertia-gravity waves
  • Meteorology

ASJC Scopus subject areas

  • General

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