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Published December 2016 | Published
Journal Article Open

The Dynamics of Mesoscale Winds in the Upper Troposphere and Lower Stratosphere


Spectral analysis is applied to infer the dynamics of mesoscale winds from aircraft observations in the upper troposphere and lower stratosphere. Two datasets are analyzed: one collected aboard commercial aircraft and one collected using a dedicated research aircraft. A recently developed wave–vortex decomposition is used to test the observations' consistency with linear inertia–gravity wave dynamics. The decomposition method is shown to be robust in the vicinity of the tropopause if flight tracks vary sufficiently in altitude. For the lower stratosphere, the decompositions of both datasets confirm a recent result that mesoscale winds are consistent with the polarization and dispersion relations of inertia–gravity waves. For the upper troposphere, however, the two datasets disagree: only the research aircraft data indicate consistency with linear wave dynamics at mesoscales. The source of the inconsistency is a difference in mesoscale variance of the measured along-track wind component. To further test the observed flow's consistency with linear wave dynamics, the ratio between tropospheric and stratospheric mesoscale energy levels is compared to a simple model of upward-propagating waves that are partially reflected at the tropopause. For both datasets, the observed energy ratio is roughly consistent with the simple wave model, but wave frequencies diagnosed from the data draw into question the applicability of the monochromatic theory at wavelengths smaller than 10 km.

Additional Information

© 2016 American Meteorological Society. (Manuscript received 11 April 2016, in final form 27 July 2016) We thank Fuqing Zhang for giving us access to the START08 data. Valuable feedback from Peter Bartello, Chris Snyder, and an anonymous reviewer are gratefully acknowledged. Financial support for JC and RF came from the U.S. National Science Foundation under Grant OCE-1233832 and for OB from the U.S. National Science Foundation under Grants DMS-1516324 and DMS-1312159 as well as from the U.S. Office of Naval Research under Grant 141512355.

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