Studies of inertio‐gravity waves on midlatitude beta‐plane without the traditional approximation

Kasahara, Akira; Gary, John

doi:10.1002/qj.586

Cited by 5 publications

(3 citation statements)

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“…Using these equations including NCT, the influences of NCT were examined in terms of atmospheric waves (Thuburn et al 2002a(Thuburn et al , 2002bKasahara 2003Kasahara , 2004Durran and Bretherton 2003;Raymond 2001;Fruman et al 2009;Kasahara and Gary 2010), symmetric instability (Itano and Maruyama 2009;Itano and Kasahara 2011), and cumulus convection in the tropics (Hayashi and Itoh 2012). Thuburn et al (2002a) numerically obtained normal modes using a spherical model including NCT.…”

Section: Introductionmentioning

confidence: 99%

“…Yasuda and Sato (2012) showed the presence of waves trapped in an altitude region where the static stability is minimized. Kasahara and Gary (2010) found external Rossby waves using equations in the simplified non-TA β-plane in which some terms involved with the latitudinal variation of f are ignored (White 2002). Hayashi and Itoh (2012) used a quasi-hydrostatic and equatorial β-plane model to examine the effect of NCT on tropical cumulus convection.…”

Section: Introductionmentioning

confidence: 99%

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Kelvin and Rossby Waves Trapped at Boundaries under the Full Coriolis Force

Kohma

Sato

2013

SOLA

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It is shown that there are two types of wave solutions trapped at the boundaries which owe to the Coriolis force proportional to the meridional component of the earth's rotation vector (hereafter referred to as the f H force) under the nontraditional approximation (non-TA). One is a type of Kelvin waves (non-TA Kelvin waves) trapped on the eastern and western boundaries. Unlike traditional Kelvin waves (TA Kelvin waves), non-TA Kelvin waves trapped on the western (eastern) boundary can have northward (southward) phase and group velocities in the Northern Hemisphere (NH). The other is a type of Rossby waves trapped on the ground. The external Rossby waves can have wave structure in the vertical and amplitudes decaying with height. Moreover, the f H force modifies even the characteristics of TA Kelvin waves trapped on the southern and northern boundaries: In the NH, the Kelvin waves trapped on the southern boundary have an upper limit (k c ) to the zonal wavenumber (k), and those with large k (> k c ) trapped on the northern boundary have eastward phase velocity in the NH. The latter is regarded as the third type of edge waves unique to non-TA.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kelvin and Rossby Waves Trapped at Boundaries under the Full Coriolis Force

Kohma

Sato

2013

SOLA

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“…Kasahara and Gary (2010) showed that the superinertial and sub-inertial modes are not largely affected by the beta effect. In particular, the beta effect may be important for the trapped waves at the equator, where fV is zero, and hence, ω min is zero (2.11), indicating that the trapped solution does not exist in the linearized Boussinesq model.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

The Effect of the Horizontal Component of the Angular Velocity of the Earth's Rotation on Inertia-Gravity Waves

Yasuda

Sato

2013

Journal of the Meteorological Society of Japan

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By using a linearized Boussinesq model on the tangent plane in the mid-latitudes, how the effect of the horizontal component of the angular velocity of the Earthʼs rotation ( fH-effect) modies the characteristics of inertia-gravity waves is examined. The fH-effect widens the range of the intrinsic wave frequency. A physical interpretation of this modication is made in terms of restoring forces. There are cases in which the rotational direction of the hodograph with time is anticlockwise (clockwise) even in the Northern (Southern) Hemisphere, unlike the case of fH = 0. Considering the form stress over the potential temperature surface, the sign of the vertical group velocity can be the same as that of the vertical phase speed, unlike the case of fH = 0, because the fH-effect can reverse the direction of the form stress through the vertical force balance. The minimum frequency increases with the buoyancy frequency (N) for fH ≠ 0, when the latitude and the direction of the wavevector are xed. This fact indicates that waves trapped in a weakly stratied layer (WSL) exist, where N is low. Using an idealized vertical prole of N in the form of a square well, the trapped wave solution is derived. The solution is composed of two plane waves in the WSL, while it decays exponentially outside. Using operational radiosonde data in Japan, it is shown that there is a persistent WSL slightly below the tropopause where the climatological minimum value of N (Nmin) is about a half times lower than the typical tropospheric value (~0.01 s −1 ). The Nmin value is not sufficiently small to form trapped waves having wavelengths in a realistic range within a few days, because the condition of Nmin < 0.001 s −1 is necessary. Thus, such trapped waves are rarely observed in the WSL slightly below the tropopause.

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