Observational Evidence of Internal Inertia-Gravity Waves in the Tropical Stratosphere

Cadet, Daniel; Teitelbaum, H.

doi:10.1175/1520-0469(1979)036<0892:oeoiig>2.0.co;2

Cited by 60 publications

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“…Nevertheless, all the rays are traced back to lower latitudes than 14*N. By and large, results of the ray tracing calculation show that the inertial waves observed at around 21 km over the radar site originated in the tropics and have propagated slowly toward mid-latitudes spending about a week. Cadet and Teitelbaum (1979) and Maekawa et al (1984) reported evidence of inertial gravity waves with a 1000 km wavelength in the tropics. We can reasonably speculate that super clusters appearing in the ITCZ with more than a 1000 km horizontal scale are excited by daily radiative forcing and emit strong large-scale gravity waves near the top of cumulus convections.…”

Section: Lighthill (1978)mentioning

confidence: 99%

Characteristics of Internal Inertial Gravity Waves and Inertial Waves in the Lower Stratosphere Observed by the MU Radar

Ushimaru

Tanaka

1990

Journal of the Meteorological Society of Japan

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The MU radar observations were carried out for continuous five days each in September 1985 and1986 to reveal characteristics of internal gravity waves in the upper troposphere and lower stratosphere. Hodograph analysis and rotary spectral analyses in the vertical direction and time series of the data lead to the following results; (i) Upward propagating and saturating internal inertial gravity waves (IIGWs) are evidently observed through out all the observations in the lower region of the stratosphere lying above the tropopause. The waves are quasi-monochromatic, and representative wave parameters are a horizontal scale of 200 km (ranging from 110 to 330 km), a vertical wavelength of 1 to 2.5 km, a wave amplitude of several ms -1, and a horizontal phase velocity of 3 ms -1. The vertical wavelength and wave amplitude decrease with increasing height and the waves disappear in the vicinity of the Jones' critical level around 19 km. (ii) Another kind of upward-propagating inertial gravity wave, an inertial wave whose period is very close to inertial period is observed at the zonal mean wind turning level, separately from IIGWs just above the tropopause. The horizontal and vertical wavelengths of the wave are about 1000 km and 2 km, respectively, and the wave amplitude about 3 ms-1.We discuss propagation and origin of IIGWs and the inertial wave based on the wave parameters obtained from analyses. From an estimation of the group velocity of IIGWs, it is indicated that IIGWs are advected by the zonal mean wind and then the observed waves around a height of 17 km at the MU radar site (34*51' N, 136*06' E) are likely to have originated more than 1000 km west of the site. Ray tracing of the wave packet on a meridional plane shows that the inertial wave may have been propagated from the tropical upper troposphere over a period of about a week.

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Section: Lighthill (1978)mentioning

confidence: 99%

Characteristics of Internal Inertial Gravity Waves and Inertial Waves in the Lower Stratosphere Observed by the MU Radar

Ushimaru

Tanaka

1990

Journal of the Meteorological Society of Japan

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“…In contrast, IG waves have not been frequently observed and most studies of these waves use data from a single radiosonde station which are unable to determine whether the waves are eastward-or westward-propagating (e.g. Cadet and Teitelbaum 1979). The first study to look at signals of IG waves over several stations (Wada et al 1999) occurred in the easterly QBO regime and was able to attribute disturbances with a period of ≈2 days to eastward-propagating inertio-gravity (EIG) waves with n = 0 and n = 1; however the propagation characteristics of waves in the stratosphere are strongly affected by the mean zonal wind, and a similar study in the westerly QBO phase is required to see if westward-propagating inertio-gravity (WIG) waves can be observed.…”

Section: Introductionmentioning

confidence: 99%

Equatorial waves in the lower stratosphere. I: A novel detection method

Tindall

Thuburn

Highwood

2006

Quart J Royal Meteoro Soc

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SUMMARYWavenumber-frequency spectral analysis and linear wave theory are combined in a novel method to quantitatively estimate equatorial wave activity in the tropical lower stratosphere. The method requires temperature and velocity observations that are regularly spaced in latitude, longitude and time; it is therefore applied to the ECMWF 15-year re-analysis dataset (ERA-15). Signals consistent with idealized Kelvin and Rossby-gravity waves are found at wavenumbers and frequencies in agreement with previous studies. When averaged over 1981-93, the Kelvin wave explains approximately 1 K 2 of temperature variance on the equator at 100 hPa, while the Rossby-gravity wave explains approximately 1 m 2 s −2 of meridional wind variance. Some inertio-gravity wave and equatorial Rossby wave signals are also found; however the resolution of ERA-15 is not sufficient for the method to provide an accurate climatology of waves with high meridional structure.

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“…Studies of smaller-scale inertia-gravity waves in the lower stratosphere have been performed, and understanding of their contribution to the mean flow has been renewed by observational analyses and numerical simulations. Cadet and Teitelbaum (1979) analyzed the data of soundings launched from a research vessel during the GATE (GARP [Global Atmospheric Research Programme] Atlantic Tropical Experiment) and showed the inertia-gravity waves propagate westward in the easterly shear background flow. Tsuda et al (1994) discussed the characteristics of gravity waves in the equatorial region by analyzing rawinsonde measurements of wind velocity and temperature fluctuations from February 27 to March 22, 1990 in east Java, Indonesia (7.6oS, 112.7oE).…”

Section: Introductionmentioning

confidence: 99%

Equatorial Inertia-Gravity Waves in the Lower Stratosphere Revealed by TOGA-COARE TOP Data

Wada

Nitta

Sato

1999

Journal of the Meteorological Society of Japan

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Short-period disturbances in the equatorial lower stratosphere are analyzed by using radiosonde data of horizontal winds and temperature at 10 stations during the TOGA-COARE intensive observational period (IOP). The analysis is focused on disturbances whose periods are shorter than about 3 days.Time-height cross sections of both horizontal winds and temperature show the existence of disturbances with periods of about two days and vertical wavelengths of 3-5km. First, we made power and cross-spectral analyses. Dominant disturbances in northern [7oN-8oN] and southern [9oS-11oS] areas of the TOGA-COARE Large-scale Soundings Array (LSA) regions, propagate eastward and have similar structure in which vertical and horizontal wavelengths are 3-4km and several to ten thousand kilometers, respectively. The phase differences between the zonal and meridional wind components at one location, and the phase differences in wind components between the northen and southern regions, exhibit the typical structure of equatorially-trapped inertia-gravity waves. In the TOGA-COARE LSA equatorial area, dominant disturbances have vertical wavelengths of 4-5 km which are a little longer than those observed in the northern and southern areas. Phase differences are clear for meridional wind components between zonally separated stations, and show that the horizontal wavelengths are three to four thousand kilometers, and that the disturbances propagate eastward. On the other hand, phase differences between tonally separated stations for zonal wind components are not significant.Next, a composite analysis was made with a reference of convective activity in the troposphere. Short period disturbances with 3-5km vertical wavelengths, which are consistent with the results of the spectral analysis, appear in the composite of lag-time-height sections in the lower stratosphere, indicating that these disturbances be strongly linked to the convective activity. Vertical phase propagation is downward in the upper troposphere and lower stratosphere, showing that these disturbances propagate energy upward there.Possible equatorially-trapped modes having the wave structures revealed by the above spectral and composite analysis are estimated using the theoretical dispersion relation. It is likely that the disturbances in the northern and southern areas correspond to n=1 eastward inertia-gravity waves. The possible modes in the equatorial regions are different for zonal and meridional wind disturbances, because odd (even) modes have zonal (meridional) wind component only.The estimated wave parameters for meridional wind disturbances are consistent with n=0 inertiagravity waves propagating eastward. The disturbances dominant in the zonal wind component in the equatorial areas which do not show clear coherent zonal structure are probably due to a mixture of n=-1 Kelvin waves, n=1 eastward and westward inertia-gravity waves.

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Observational Evidence of Internal Inertia-Gravity Waves in the Tropical Stratosphere

Cited by 60 publications

References 0 publications

Characteristics of Internal Inertial Gravity Waves and Inertial Waves in the Lower Stratosphere Observed by the MU Radar

Characteristics of Internal Inertial Gravity Waves and Inertial Waves in the Lower Stratosphere Observed by the MU Radar

Equatorial waves in the lower stratosphere. I: A novel detection method

Equatorial Inertia-Gravity Waves in the Lower Stratosphere Revealed by TOGA-COARE TOP Data

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