Not All Clear Air Turbulence Is Kolmogorov—The Fine‐Scale Nature of Atmospheric Turbulence

Medientyp: E-Artikel

Titel: Not All Clear Air Turbulence Is Kolmogorov—The Fine‐Scale Nature of Atmospheric Turbulence

Beteiligte: Rodriguez Imazio, Paola [VerfasserIn]; Mininni, Pablo D. [VerfasserIn]; Godoy, Alejandro [VerfasserIn]; Rivaben, Nicolás [VerfasserIn]; Dörnbrack, Andreas [VerfasserIn]; 1 Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires Argentina [VerfasserIn]; 3 Facultad de Ciencias Exactas y Naturales Departamento de Física Ciudad Universitaria, Universidad de Buenos Aires Buenos Aires Argentina [VerfasserIn]; 2 Servicio Meteorológico Nacional Buenos Aires Argentina [VerfasserIn]

Erschienen: GEO-LEOe-docs (FID GEO), 2023-01-20

Sprache: Englisch

DOI: https://doi.org/10.1029/2022JD037491

Schlagwörter: southern Andes ; gravity waves dynamics ; clear air turbulence (CAT) ; German High-Altitude Long-Range research aircraft (HALO)

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Beschreibung: We study a strong clear air turbulence (CAT) event experienced by the German High‐Altitude Long‐Range research aircraft (HALO) during the Southern Hemisphere Transport, Dynamics, and Chemistry campaign. HALO encountered CAT leeward of the southern Andes Mountains, where tropospheric airflow favored vertically propagating mountain waves that were refracted southeastward into the core of tropopause jet. Turbulence is quantified using spectral quantities and structure functions computed from in situ 100 Hz flight level data. The detected CAT region exhibits strong patchiness, characterized by separated bursts in turbulent kinetic energy and energy dissipation rate. The high resolution in situ observations reveal different turbulent scaling within each patch, in both spectra and structure functions, and following Monin and Yaglom's conversion law. One patch follows power laws with exponents −1.71 ± 0.06, −1.771 ± 0.006, and −1.56 ± 0.05 for the velocity components w, v, and u, respectively, while another patch has exponents −2.17 ± 0.12, −2.50 ± 0.08, and −1.92 ± 0.09. These patches are mediated by a third patch with less clear scaling. While the patches can deviate from Kolmogorov scaling due to the anisotropy of the airflow, they still display evidence of CAT with enhanced energy dissipation rates. ; Plain Language Summary: Clear air turbulence (CAT) is a common phenomenon in upper layers of the atmosphere, often triggered by the instability of internal gravity waves or by strong wind shear. CAT can be disruptive for airplanes and uncomfortable for pilots and passengers. Nevertheless, the relationship between CAT formation and the resulting strength of bumpiness experienced by an aircraft is not fully understood. Most of these turbulent regions are patchy and exhibit sudden inhomogeneous bursts of velocity and temperature variations. However, CAT is often quantified using spectral quantities assuming isotropic and homogeneous turbulence. Here, we present a case study of a CAT event observed in the lowermost ...

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