Physical parameters of gravity wave packet propagation contained in radar RTI plots

Kuo, F. S.; Lue, H. Y.; Luo, Changan

doi:10.1016/s1364-6826(97)00126-0

Cited by 4 publications

(13 citation statements)

References 2 publications

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“…(13) in the text) can be obtained by the following procedure (Kuo et al, 1998): At each time step t i =i t and radial range r k =k r, a time series of N data points (N is chosen to be 15 in this paper) is defined by k = (r k , t ) , = i − …”

Section: Methods Of Phase-and Group-velocity Tracingmentioning

confidence: 99%

“…An example of the RTI plot of the numerical wave packet generated by Eq. (13) and converted by the phase and group velocity tracing technique (Kuo et al, 1998) is demonstrated in Fig. 2.…”

Section: Theorymentioning

confidence: 99%

“…Considering P ki as an index of the strength of the wave activity at radial range r k and time t i , we plot the matrix [P ki ] as an RTI plot for investigation (we use the contour plot to represent the RTI plot in this paper). A numerical simulation study (Kuo et al, 1998) showed that when a wave packet is propagating, packets with high regularity would exist in the RTI plot. It was shown that the same phase points of the characteristic wave component of the wave packet form a straight line called a phase trajectory, while the centers of the neighboring packets form another straight line called an energy trajectory.…”

Section: (A2)mentioning

confidence: 99%

“…Therefore, group velocity is a valuable parameter (in addition to wave period and phase velocity) to characterize the gravity wave. And a method called phase-and groupvelocity tracing was developed (Kuo et al, 1998) to analyze the phase-and group-velocities of any kind of wave propagation.…”

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confidence: 99%

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Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

2007

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Abstract. The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (v pr and v gr ), with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase-and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity v pr , and the slope of the energy line across the neighboring striations is equal to the radial group velocity v gr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ . Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.

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Section: Methods Of Phase-and Group-velocity Tracingmentioning

confidence: 99%

“…An example of the RTI plot of the numerical wave packet generated by Eq. (13) and converted by the phase and group velocity tracing technique (Kuo et al, 1998) is demonstrated in Fig. 2.…”

Section: Theorymentioning

confidence: 99%

Section: (A2)mentioning

confidence: 99%

mentioning

confidence: 99%

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Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

2007

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“…Therefore, analysis of the group velocities is necessary to understand the characteristics of gravity wave propagation. A method of wave packet analysis called phase-and group-velocity-tracing (Kuo et al, 1998) was developed to measure the group velocity, phase velocity along any specific direction and the characteristic wave period of a wave packet of any kind of wave. And this method was further proved by numerical simulation to be reasonably accurate in measuring the phase-and group-velocities of the projected wave packet motion of gravity wave along any oblique radar beam (Kuo et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2009

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Abstract. We study the horizontal structure of the atmospheric gravity waves (AGW) in the height ranges between 6 and 22 km observed using the MU radar at Shigaraki in Japan, during a 3 day period in January and a 4 day period in August 1988. The data were divided by double Fourier transformation into a data set of upward moving waves and a data set of downward moving waves for independent analysis. The phase and group velocity tracing technique was applied to measure the vertical group and phase velocity as well as the characteristic period of the gravity wave packet. Then the dispersion equation of the linear theory of AGW was solved to obtain its intrinsic wave period -horizontal wavelength and horizontal group velocity -and the vertical flux of horizontal momentum associated with each wave packet was estimated to help determine the direction of the characteristic horizontal wave vector. The results showed that the waves with periods in the range of 30 min∼6 h had horizontal scales ranging from 20 km to 1500 km, vertical scales from 4 km to 15 km, and horizontal phase velocities from 15 m/s to 60 m/s. The upward moving wave packets of wave period of 2 h∼6 h had horizontal group velocities mainly toward eastsouth-east and northeast in winter, and mainly in the section between the directions of west-north-west and north in summer.

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Studies of vertical fluxes of horizontal momentum in the lower atmosphere using the MU-radar

et al. 2008

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Abstract.We study the momentum flux of the atmospheric motions in the height ranges between 6 and 22 km observed using the MU radar at Shigaraki in Japan during a 3 day period in January 1988. The data were divided by double Fourier transformation into data set of waves with downward-phase-velocity and data set of waves with upward-phase-velocity for independent momentum flux calculation. The result showed that both the 72 h averaged upward flux and downward flux of zonal momentum were negative at nearly each height, meaning that the upward flux was dominated by westward propagating waves while the downward flux was dominated by eastward propagating waves. The magnitude of the downward flux was approximately a factor of 1.5 larger than the upward flux for waves in the 2∼7 h and 7∼24 h period bands, and about equal to the upward flux in the 10-30 min and 30 min-2 h period bands. It is also observed that the vertical flux of zonal momentum tended to be small in each frequency band at the altitudes below the jet maximum (10∼12 km), and the flux increased toward more negative values to reach a negative maximum at some altitude well above the jet maximum. Daily averaged flux showed tremendous variation: The 1st 24 h (quiet day) was relatively quiet, and the fluxes of the 2nd and 3rd 24 h (active days) increased sharply. Moreover, the upward fluxes of zonal momentum below 17 km in the quiet day for each period band (10∼30 min, 30 min∼2 h, 2∼7 h, and 7∼24 h) were dominantly positive, while the corresponding downward fluxes were dominantly negative, meaning that the zonal momentum below 17 km in each period band under study were dominantly eastward (propagating along the mean wind). In the active days, both the upward fluxes and Correspondence to: F. S. Kuo (fskuo@msa.vnu.edu.tw) downward fluxes in each frequency band were dominantly negative throughout the whole altitude range 6.1-18.95 km.

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Physical parameters of gravity wave packet propagation contained in radar RTI plots

Cited by 4 publications

References 2 publications

Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

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

Studies of vertical fluxes of horizontal momentum in the lower atmosphere using the MU-radar

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