Statistical characteristics of AGW wave packet propagation in the lower atmosphere observed by the MU radar

Kuo, F. S.; Lue, H. Y.; Fern, C. L.; Röttger, J.; Fukao, S.; Yamamoto, M.

doi:10.5194/angeo-27-3737-2009

Cited by 4 publications

(17 citation statements)

References 20 publications

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“…So, both case studies (Sects. 3.3.1 and 3.4) revealed that the results of wave packet analysis were closely associated with the high frequency part of the wave spectrum in Table 2c, because high frequency waves had better relative frequency resolution ω ω than low frequency waves (Kuo et al, 2003(Kuo et al, , 2009). The results of hodograph analysis associated with these 20 wave packets were shown by a green dot in Fig.…”

Section: Superposition Of Five Waves Propagating In Same Direction Vementioning

confidence: 96%

“…Then the most probable characteristic intrinsic frequency, horizontal wavelength and azimuth of each wave packet can be found by fitting the dispersion equation and its related formula for vertical group velocity (Kuo et al, 2009). In this paper, we shall compare the merit and demerit of each method and try to find a composite procedure for obtaining the most probable propagation parameters of AGWs.…”

Section: H Y Lue and F S Kuo: Comparative Studies Of Methods Of Omentioning

confidence: 99%

“…If the background wind is not negligible, some waves may be Doppler shifted into negative intrinsic frequency (see Eq. 1a) causing their vertical group velocities and phase velocities to have the same sense of vertical propagation, and we called such wave packets as type 2 wave packets (Kuo et al, 2003(Kuo et al, , 2008(Kuo et al, , 2009Kuo and Röttger, 2005). Phase and group velocity tracing technique can unambiguously identify the location (height and time) of type 1 and type 2 wave packets.…”

Section: On Stokes Parameters/rotary Spectra Methods and Technique Of mentioning

confidence: 99%

“…(1a), (1b) and (10). And the true azimuth can be determined from these two symmetric azimuths with the help of momentum flux measurement (Kuo et al, 2009). …”

Section: Phase and Group Velocity Tracing Analysismentioning

confidence: 99%

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Comparative studies of methods of obtaining AGW's propagation properties

Lue

Kuo

2012

Ann. Geophys.

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Abstract. Three among the existing methods of obtaining the properties (intrinsic period, wavelength, propagation direction) of atmospheric gravity waves (AGWs) were compared and studied by numerical method to simulate radar data. Three-dimensional fluctuation velocity satisfying dispersion equation and polarization relation of atmospheric gravity wave were generated, then the numerical data were analysed by these methods to obtain the properties of waves. We found that, hodograph analysis was accurate for a monochromatic wave in obtaining its wave period and propagation direction, but the analysis became erratic for the case of multiple waves' superposition. The error was especially large when data consisted of both upward propagating waves and downward propagating waves. The hodograph method became meaningful again if all the component waves propagated in the same direction and the resulting period was dominantly decided by the lowest frequency wave. Stokes parameters method would obtain statistically meaningful values of wave period and azimuth if the spreading of the azimuths among the component waves did not exceed 90 • and the resulting period and azimuth were dominated by the lowest frequency wave component as well, irrespective of the vertical sense of propagation. Another method called phase and group velocity tracing technique was reconfirmed to be meaningful in measuring the characteristic wave period and vertical group and phase velocities of a wave packet: the characteristic wave period and vertical wavelength was dominated by the wave with the highest frequency among the component waves in the wave packet. Based on these numerical results, a composite procedure of data analysis for wave propagation was proposed and an example of real data analysis was presented.

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Section: Superposition Of Five Waves Propagating In Same Direction Vementioning

confidence: 96%

Section: H Y Lue and F S Kuo: Comparative Studies Of Methods Of Omentioning

confidence: 99%

Section: On Stokes Parameters/rotary Spectra Methods and Technique Of mentioning

confidence: 99%

“…(1a), (1b) and (10). And the true azimuth can be determined from these two symmetric azimuths with the help of momentum flux measurement (Kuo et al, 2009). …”

Section: Phase and Group Velocity Tracing Analysismentioning

confidence: 99%

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Comparative studies of methods of obtaining AGW's propagation properties

Lue

Kuo

2012

Ann. Geophys.

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“…Therefore, the traditional hodograph analysis in fact can only be applied to study low-frequency GWs. Observational studies on lower-atmospheric medium-and high-frequency GWs (MHGWs) are mainly from only radiosonde at a tropical station (Leena et al, 2012b) and few radar observations at several limited sites (Dutta et al, 2009;Kuo et al, 2009, Leena et al, 2012b. Then, considering the long-term accumulations and extensive land distribution of radiosonde observations, in order to further understand the MHGWs in the lower atmosphere we need a feasible method to extract MHGW parameters from more radiosonde observations.…”

Section: S D Zhang Et Al: Spatial and Seasonal Variability Of Medimentioning

confidence: 99%

Spatial and seasonal variability of medium- and high-frequency gravity waves in the lower atmosphere revealed by US radiosonde data

Zhang

Huang

et al. 2014

Ann. Geophys.

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Abstract. We extended the broad spectral method proposed by Zhang et al. (2013) for the extraction of medium-and high-frequency gravity waves (MHGWs). This method was applied to 11 years (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) of radiosonde data from 92 stations in the Northern Hemisphere to investigate latitudinal, continuous vertical and seasonal variability of MHGW parameters in the lower atmosphere (2-25 km). The latitudinal and vertical distributions of the wave energy density and horizontal momentum fluxes as well as their seasonal variations exhibit considerable consistency with those of inertial gravity waves. Despite the consistency, the MHGWs have much larger energy density, horizontal momentum fluxes and wave force, indicating the more important role of MHGWs in energy and momentum transportation and acceleration of the background. For the observed MHGWs, the vertical wavelengths are usually larger than 8 km; the horizontal wavelengths peak in the middle troposphere at middle-high latitudes. These characteristics are obviously different from inertial gravity waves. The energy density and horizontal momentum fluxes have similar latitude-dependent seasonality: both of them are dominated by a semiannual variation at low latitudes and an annual variation at middle latitudes; however at high latitudes, they often exhibit more than two peaks per year in the troposphere. Compared with the inertial GWs, the derived intrinsic frequencies are more sensitive to the spatiotemporal variation of the buoyancy frequency, and at all latitudinal regions they are higher in summer. The wavelengths have a weaker seasonal variation; an evident annual cycle can be observed only at middle latitudes.

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Studies of gravity wave propagation in the mesosphere observed by MU radar

et al. 2013

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Abstract. Mesospheric data were analyzed by a composite method combining phase and group velocity tracing technique and the spectra method of Stokes parameter analysis to obtain the propagation parameters of atmospheric gravity waves (AGW) in the height ranges between 63.6 and 99.3 km, observed using the MU radar at Shigaraki in Japan in the months of November and July in the years 1986, 1988 and 1989. The data of waves with downward phase velocity and the data of waves with upward phase velocity were independently treated. First, the vertical phase velocity and vertical group velocity as well as the characteristic wave period for each wave packet were obtained by phase and group velocity tracing technique. Then its horizontal wavelength, intrinsic wave period and horizontal group velocity were obtained by the dispersion relation. The intrinsic frequency and azimuth of wave vector of each wave packet were checked by Stokes parameters analysis. The results showed that the waves with intrinsic periods in the range 30 min–4.5 h had horizontal wavelength ranging from 25 to 240 km, vertical wavelength from 2.5 to 12 km, and horizontal group velocities from 15 to 60 m s−1. Both upward moving wave packets and downward moving wave packets had horizontal group velocities mostly directed in the sector between directions NNE (north-north-east) and SEE in the month of November, and mostly in the sector between directions NW and SWS in the month of July. Comparing with mean wind directions, the gravity waves appeared to be more likely to propagate along with mean wind than against it. This apparent prevalence for downstream wave packets was found to be caused by a systematic filtering effect existing in the process of phase and group velocity tracing analysis: A significant portion of upstream wave packets might have been Doppler shifted out of the vertical range in phase and group velocity tracing analysis.

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Statistical characteristics of AGW wave packet propagation in the lower atmosphere observed by the MU radar

Cited by 4 publications

References 20 publications

Comparative studies of methods of obtaining AGW's propagation properties

Comparative studies of methods of obtaining AGW's propagation properties

Spatial and seasonal variability of medium- and high-frequency gravity waves in the lower atmosphere revealed by US radiosonde data

Studies of gravity wave propagation in the mesosphere observed by MU radar

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