Properties of the average distribution of equatorial Kelvin waves investigated with the GROGRAT ray tracer

Ern, Manfred; Cho, H.-K.; Preusse, Peter; Eckermann, Stephen D.

doi:10.5194/acp-9-7973-2009

Cited by 11 publications

(8 citation statements)

References 63 publications

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“…In our study we make use of the longitude‐time spectral analysis method described by Ern et al [2008, 2009a, 2009b] and Ern and Preusse [2009]. The SABER and ECMWF residual temperatures used in our analysis are arranged into non‐overlapping latitude‐altitude bins.…”

Section: Analysis Methodsmentioning

confidence: 99%

Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere

Ern

Preusse

2009

Geophysical Research Letters

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[1] Both global scale waves (e.g., Kelvin, equatorial Rossby, or Rossby-gravity waves) and mesoscale gravity waves contribute to the wind reversals of the quasi biennial oscillation (QBO). The relative contributions of the different wave types are highly uncertain. In our work we quantify the contribution of equatorial Kelvin waves to the reversal from stratospheric easterlies to westerlies averaged over two QBO cycles in the period 2002-2006. Our analysis is based on longitude-time spectra of temperatures measured by the SABER satellite instrument, as well as temperatures from ECMWF operational analyses. Kelvin waves of zonal wavenumber 1 -6 and periods longer than 2.5 days are covered. It is found that the contribution of Kelvin waves is about 30-50% of the observed wind reversal and only 20-35% of the expected total wave forcing. The larger part of the wave forcing therefore has to be contributed by other waves, likely mesoscale gravity waves. Citation: Ern, M., and P. Preusse (2009), Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere, Geophys. Res. Lett., 36, L21801,

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Section: Analysis Methodsmentioning

confidence: 99%

Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere

Ern

Preusse

2009

Geophysical Research Letters

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“…Different types of global‐scale waves often have characteristic spectral peaks in longitude‐time spectra and can therefore easily be identified and separated by band‐pass filtering. Therefore, 2d‐Fourier analysis has been successfully applied for investigation of global‐scale waves [e.g., Lait and Stanford , 1988a, 1988b; Wu et al , 1996; Garcia et al , 2005; Ern et al , 2008, 2009a, 2009b; Ern and Preusse , 2009a, 2009b].…”

Section: Estimation Of Gravity Wave Momentum Flux Absolute Valuesmentioning

confidence: 99%

Implications for atmospheric dynamics derived from global observations of gravity wave momentum flux in stratosphere and mesosphere

Ern¹,

Preusse²,

Gille³

et al. 2011

J. Geophys. Res.

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244

461

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[1] In this work absolute values of gravity wave (GW) momentum flux are derived from global temperature measurements by the satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). Momentum fluxes in the stratosphere are derived for both instruments and for SABER in the whole mesosphere. The large-scale atmospheric background state is removed by a two-dimensional Fourier decomposition in longitude and time, covering even planetary-scale waves with periods as short as 1-2 days. Therefore, it is possible to provide global distributions of GW momentum flux from observations for the first time in the mesosphere. Seasonal as well as longer-term variations of the global momentum flux distribution are discussed. GWs likely contribute significantly to the equatorward tilt of the polar night jet and to the poleward tilt of the summertime mesospheric jet. Our results suggest that GWs can undergo large latitudinal shifts while propagating upward. In particular, GWs generated by deep convection in the subtropical monsoon regions probably contribute significantly to the mesospheric summertime wind reversal at mid-and high latitudes. Variations in the GW longitudinal distribution caused by those convectively generated GWs are still observed in the mesosphere and could be important for the generation of the quasi two-day wave. Indications for quasi-biennial oscillation (QBO) induced variations of GW momentum flux are found in the subtropics. Also variations at time scales of about one 11-year solar cycle are observed and might indicate a negative correlation between solar flux and GW momentum flux.Citation: Ern, M., P. Preusse, J. C. Gille, C. L. Hepplewhite, M. G. Mlynczak, J. M. Russell III, and M. Riese (2011), Implications for atmospheric dynamics derived from global observations of gravity wave momentum flux in stratosphere and mesosphere,

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“…Most global observations of GWMF from space are based on small‐scale fluctuations extracted from global observations of atmospheric temperatures. Assuming hydrostatic equilibrium, and using the linear polarization relations for GWs [e.g., Fritts and Alexander , ; Ern et al , , ], equation can be rewritten in terms of temperature amplitudes

\overset{T}{false}

and the vector ( k , l , m ) of zonal, meridional, and vertical GW wave numbers:

((), F_{px}, F_{py}) = \frac{1}{2} ϱ {((), \frac{g}{N})}^{2} \frac{(k, l)}{m} {((), \frac{\overset{T}{false}}{\overset{T}{false}})}^{2}

with N the buoyancy frequency, g the Earth's gravity acceleration, and

\overset{T}{false}

the atmospheric background temperature. For assumptions and approximations that were made for this equation, and to which extent these hold for the GWs seen by AIRS, see the “supporting information.” Equation can also be rewritten for GWMF absolute values F ph by introducing the horizontal wave number

k_{h} = \sqrt{k^{2} + l^{2}}

in the propagation direction of a GW considered:

F_{normalph} = \frac{1}{2} ϱ {((), \frac{g}{N})}^{2} \frac{k_{h}}{m} {((), \frac{\overset{T}{false}}{\overset{T}{false}})}^{2}

For more details, see also Ern et al [].…”

Section: Introductionmentioning

confidence: 99%

“…Most global observations of GWMF from space are based on small-scale fluctuations extracted from global observations of atmospheric temperatures. Assuming hydrostatic equilibrium, and using the linear polarization relations for GWs [e.g., Fritts and Alexander, 2003;Ern et al, 2004Ern et al, , 2009, equation (1) can be rewritten in terms of temperature amplitudesT and the vector (k, l, m) of zonal, meridional, and vertical GW wave numbers:…”

Section: Introductionmentioning

confidence: 99%

Directional gravity wave momentum fluxes in the stratosphere derived from high‐resolution AIRS temperature data

Ern

Hoffmann

Preusse

2017

Geophysical Research Letters

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136

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In order to reduce uncertainties in modeling the stratospheric circulation, global observations of gravity wave momentum flux (GWMF) vectors are required for comparison with distributions of resolved and parametrized GWMF in global models. For the first time, we derive GWMF vectors globally from data of a nadir‐viewing satellite instrument: we apply a 3‐D method to an Atmospheric Infrared Sounder (AIRS) temperature data set that was optimized for gravity wave (GW) analysis. For January 2009, the resulting distributions of GW amplitudes and of net GWMF highlight the importance of GWs in the polar vortex and the summertime subtropics. Net GWMF is preferentially directed opposite to the background wind, and, interestingly, it is dominated by large‐amplitude GWs of relatively long horizontal wavelength. For convective GW sources, these large horizontal scales are in contradiction with traditional thoughts. However, the observational filter effect needs to be kept in mind when interpreting the results.

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Properties of the average distribution of equatorial Kelvin waves investigated with the GROGRAT ray tracer

Cited by 11 publications

References 63 publications

Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere

Quantification of the contribution of equatorial Kelvin waves to the QBO wind reversal in the stratosphere

Implications for atmospheric dynamics derived from global observations of gravity wave momentum flux in stratosphere and mesosphere

Directional gravity wave momentum fluxes in the stratosphere derived from high‐resolution AIRS temperature data

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