The mixed Rossby–gravity wave on the spherical Earth

Paldor, Nathan; Fouxon, Itzhak; Shamir, Ofer; Garfinkel, Chaim I.

doi:10.1002/qj.3354

Cited by 15 publications

(17 citation statements)

References 12 publications

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“…For the antisymmetric component of the spectra in Figure 3, about half of the models exhibit some organization along the dispersion curves for the MRG modes (Matsuno, 1966;Paldor et al, 2018) as seen in GPCP. GPCP has a well defined peak centered around the 25 m equivalent depth contour, indicating that MRGs organize a significant portion of the precipitation variability, along with eastward propagating inertio-gravity waves (EIGs, Kiladis et al, 2016).…”

Section: Tropical Precipitation Spectramentioning

confidence: 94%

An evaluation of tropical waves and wave forcing of the QBO in the QBOi models

Holt

Lott

García

et al. 2020

Quart J Royal Meteoro Soc

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We analyze the stratospheric waves in models participating in phase 1 of the Stratosphere-troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi). All models have robust Kelvin and mixed Rossby-gravity wave modes in winds and temperatures at 50 hPa and represent them better than most of the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. There is still some spread among the models, especially concerning the mixed Rossby-gravity waves. We attribute the variability in equatorial waves among the QBOi models in part to the varying horizontal and vertical resolutions, to systematic biases in zonal winds, and to the considerable variability in convectively coupled waves in the troposphere among the models: only roughly half of the QBOi models have realistic convectively coupled Kelvin waves and only a few models have convectively coupled mixed Rossby-gravity waves. The models with stronger convectively coupled waves tend to produce larger zonal mean forcing due to resolved waves in the QBO region. Finally we evaluate the Eliassen-Palm (EP) flux and EP flux divergence of the resolved waves in the QBOi models. We find that there is a large spread in the forcing from resolved waves in the QBO region, and the resolved wave forcing has a robust correlation with model vertical resolution.

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Section: Tropical Precipitation Spectramentioning

confidence: 94%

An evaluation of tropical waves and wave forcing of the QBO in the QBOi models

Holt

Lott

García

et al. 2020

Quart J Royal Meteoro Soc

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“…Conversely, the divergence field amplitude is only 1 order of magnitude smaller than the vorticity field amplitude, which is 2.7 × 10 −11 . Regardless of the cause, the fact that all other four fields remain quite regular while the divergence field is completely eroded suggests that the small but significant divergence field described by Phillips (1959) is in fact a small and insignificant divergence field.…”

Section: Smoothness and Stabilitymentioning

confidence: 99%

“…(2) has one real root ω = √ gH k, which correspond to the equatorial Kelvin wave (see Matsuno, 1966). The existence of the latter two waves on a sphere is discussed in Garfinkel et al (2017) and Paldor et al (2018).…”

Section: The Analytic Solutionsmentioning

confidence: 99%

The Matsuno baroclinic wave test case

et al. 2019

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Abstract. The analytic wave solutions obtained by Matsuno (1966) in his seminal work on equatorial waves provide a simple and informative way of assessing the performance of atmospheric models by measuring the accuracy with which they simulate these waves. These solutions approximate the solutions of the shallow-water equations on the sphere for low gravity-wave speeds such as those of the baroclinic modes in the atmosphere. This is in contrast to the solutions of the non-divergent barotropic vorticity equation, used in the Rossby–Haurwitz test case, which are only accurate for high gravity-wave speeds such as those of the barotropic mode. The proposed test case assigns specific values to the wave parameters (gravity-wave speed, zonal wave number, meridional wave mode and wave amplitude) for both planetary and inertia-gravity waves, and suggests simple assessment criteria suitable for zonally propagating wave solutions. The test is successfully applied to a spherical shallow-water model in an equatorial channel and to a global-scale model. By adding a small perturbation to the initial fields it is demonstrated that the chosen initial waves remain stable for at least 100 wave periods. The proposed test case can also be used as a resolution convergence test.

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“…The solution space of this system corresponds to three families of solutions, each with a countable number of modes, namely, the westward-propagating inertiagravity (WIG) waves, the westward-propagating equatorial Rossby (ER) waves, and the eastward-propagating inertiagravity (EIG) waves. In addition, the solution space of the system also includes two mixed modes that fill the frequency gap between the IG waves and Rossby waves families, namely, the westward-propagating mixed Rossby-gravity (MRG) wave and the Kelvin wave (Delplace et al 2017;Garfinkel et al 2017;Paldor et al 2018). In addition to the wavenumber and mode number (that determine the wave mode), the solutions of the SW equations are also determined by the layer depth in a motionless basic state.…”

Section: Introductionmentioning

confidence: 99%

The power distribution between symmetric and anti-symmetric components of the tropical wavenumber-frequency spectrum

Shamir

Schwartz

Garfinkel

et al. 2021

Journal of the Atmospheric Sciences

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A yet unexplained feature of the tropical wavenumber-frequency spectrum is its parity distributions, i.e., the distribution of power between the meridionally symmetric and anti-symmetric components of the spectrum. Due to the linearity of the decomposition to symmetric and anti-symmetric components and the Fourier analysis, the total spectral power equals the sum of the power contained in each of these two components. However, the spectral power need not be evenly distributed between the two components. Satellite observations and reanalysis data provide ample evidence that the parity distribution of the tropical wavenumber-frequency spectrum is biased towards its symmetric component. Using an intermediate-complexity model of an idealized moist atmosphere, we find that the parity distribution of the tropical spectrum is nearly insensitive to large-scale forcing, including topography, ocean heat fluxes, and land-sea contrast. On the other hand, we find that a small-scale (stochastic) forcing has the capacity to affect the parity distribution at large spatial scales via an upscale (inverse) turbulent energy cascade. These results are qualitatively explained by considering the effects of triad interactions on the parity distribution. According to the proposed mechanism, any bias in the small-scale forcing, symmetric or anti-symmetric, leads to symmetric bias in the large-scale spectrum regardless of the source of variability responsible for the onset of the asymmetry. As this process is also associated with the generation of large-scale features in the Tropics by small-scale convection, the present study demonstrates that the physical process associated with deep-convection leads to a symmetric bias in the tropical spectrum.

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The mixed Rossby–gravity wave on the spherical Earth

Cited by 15 publications

References 12 publications

An evaluation of tropical waves and wave forcing of the QBO in the QBOi models

An evaluation of tropical waves and wave forcing of the QBO in the QBOi models

The Matsuno baroclinic wave test case

The power distribution between symmetric and anti-symmetric components of the tropical wavenumber-frequency spectrum

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