Wave–vortex decomposition of one-dimensional ship-track data

Bühler, Oliver; Callies, Jörn; Ferrari, Raffaele

doi:10.1017/jfm.2014.488

Cited by 106 publications

(194 citation statements)

References 14 publications

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“…Contrary to what we stated in Bühler et al (2014), the requirement that streamfunction and potential be uncorrelated is not needed as long as the flow statistics are isotropic. If the cospectrum C cf (k, l) depends on k h only, the integrand klC cf (k, l) is odd in l, and thus the integral over l of this cross term vanishes.…”

Section: A Helmholtz Decompositionmentioning

confidence: 74%

“…In Bühler et al (2014), we introduced a method consisting of two parts. First, a Helmholtz decomposition separates the one-dimensional spectrum of horizontal kinetic energy into a rotational part and a divergent part.…”

Section: Decomposition Methodsmentioning

confidence: 99%

“…To address this question, the method developed in Bühler et al (2014) has a second step that attempts a wave-vortex decomposition based on the assumption that the flow is a superposition of geostrophic flow and linear inertia-gravity waves. The method provides a prediction of the total hydrostatic wave energy (horizontal kinetic plus potential) based on the observations of the horizontal velocities only.…”

Section: Introductionmentioning

confidence: 99%

“…Section 2 summarizes and extends the decomposition method developed in Bühler et al (2014) and introduces the notation. Section 3 investigates the theoretical situation near a sharp tropopause and computes the detailed wave structure and wave energies above and below the tropopause.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Callies

Bühler

Ferrari

2016

Journal of the Atmospheric Sciences

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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.

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Section: A Helmholtz Decompositionmentioning

confidence: 74%

Section: Decomposition Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Callies

Bühler

Ferrari

2016

Journal of the Atmospheric Sciences

Self Cite

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“…Similar methods have also been used in order to describe the full turbulent field (Frehlich et al 2001). There has also been considerable interest in describing the statistics of the velocity field directly or via its spectrum (Bühler et al 2014;Lindborg 2015;Bierdel et al 2016). …”

Section: Introductionmentioning

confidence: 99%

A Matérn-Based Multivariate Gaussian Random Process for a Consistent Model of the Horizontal Wind Components and Related Variables

Hewer

Friederichs

Hense

et al. 2017

Journal of the Atmospheric Sciences

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The integration of physical relationships into stochastic models is of major interest, for example, in data assimilation. Here, a multivariate Gaussian random field formulation is introduced that represents the differential relations of the two-dimensional wind field and related variables such as the streamfunction, velocity potential, vorticity, and divergence. The covariance model is based on a flexible bivariate Matérn covariance function for the streamfunction and velocity potential. It allows for different variances in the potentials, nonzero correlations between them, anisotropy, and a flexible smoothness parameter. The joint covariance function of the related variables is derived analytically. Further, it is shown that a consistent model with nonzero correlations between the potentials and positive definite covariance function is possible. The statistical model is fitted to forecasts of the horizontal wind fields of a mesoscale numerical weather prediction system. Parameter uncertainty is assessed by a parametric bootstrap method. The estimates reveal only physically negligible correlations between the potentials.

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Characterizing horizontal variability and energy spectra in the Arctic Ocean halocline

2015

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Energy transfer from the atmosphere into the upper Arctic Ocean is expected to become more efficient as summer sea-ice coverage decreases and multiyear ice thins due to recent atmospheric warming. However, relatively little is known about how energy is transferred within the ocean by turbulent processes from large to small scales in the presence of ice and how these pathways might change in future. This study characterizes horizontal variability in several regions of the Eurasian Arctic Ocean under differing sea-ice conditions. Historic along track CTD data collected by a Royal Navy submarine during summer 1996 allow a unique examination of horizontal variability and associated wavenumber spectra within the Arctic Ocean halocline. Spectral analysis indicates that potential energy variance under perennial sea-ice in the Amundsen Basin is O(100) less than within the marginal ice zone (MIZ) of Fram Strait. Spectra from all regions show a transition in scaling at wavelengths of approximately 5-7 km. At scales greater than the transition wavelength to 50 km, energy spectra are consistent with a k 23 scaling (where k is a wavenumber) and interior quasigeostrophic dynamics. The scaling of spectra at these scales is extremely similar between regions suggesting similar dynamics and energy exchange pathways. The k 23 scaling is steeper than typically found in regions of midlatitude open ocean. At scales below the transition wavelength to 300 m, spectra are close to a k 25/3 scaling or flatter, indicating a change in dynamics, which is potentially due to internal waves dominating variability at small scales.

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Wave–vortex decomposition of one-dimensional ship-track data

Cited by 106 publications

References 14 publications

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

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

A Matérn-Based Multivariate Gaussian Random Process for a Consistent Model of the Horizontal Wind Components and Related Variables

Characterizing horizontal variability and energy spectra in the Arctic Ocean halocline

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