ANGEO Annales Geophysicae ANGEO 1432-0576 Copernicus GmbH Göttingen, Germany 10.5194/angeo-27-3737-2009 Statistical characteristics of AGW wave packet propagation in the lower atmosphere observed by the MU radar Kuo F. S. 1 Lue H. Y. 2 Fern C. L. 3 Röttger J. 4 5 Fukao S. 6 Yamamoto M. 6 Department of Electro-Optical Engineering, Vanung University, Chung-Li, Taiwan Department of Physics, Fu Jen University, Hsin Chuang, Taiwan Graduate School of Materials, National Yunlin University of Science and Technology, Douliou, Yunlin, Taiwan MPI for Solar System Research, Katlenburg-Lindau, Germany Institute of Space Science, National Central University, Chung-Li, Taiwan Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto, Japan 02 10 2009 27 10 3737 3753 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.ann-geophys.net/27/3737/2009/angeo-27-3737-2009.html The full text article is available as a PDF file from http://www.ann-geophys.net/27/3737/2009/angeo-27-3737-2009.pdf

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 east-south-east and northeast in winter, and mainly in the section between the directions of west-north-west and north in summer.

 References Ebel, A., Manson, A. H., and Meek, C. E.: Short period fluctuations of the horizontal wind measured in the upper middle atmosphere and possible relationships to internal gravity waves, J. Atmos. Terr. Phys., 49, 385–401, 1987. Eckermann, S. D. and Vincent, R. A.: Falling sphere observations of atmospheric gravity wave motions in the upper stratosphere over Australia, Pure Appl. Geophys., 130, 509–532, 1989. Fritts, D. C. and Alexander, M. J.: Gravity wave dynamics and effects in the middle atmosphere, Rev. Geophys., 41(1), 1003, doi:10.1029/2001RG000106, 2003. Gavrilov, N. M., Fukao, S., Nakamura, T., and Tsuda, T.: Statistical analysis of gravity waves observed with the middle and upper atmosphere radar in the middle atmosphere 2, Waves propagated in different directions, J. Geophys. Res., 102(D12), 13433–13440, 1997. Gossard, E. E. and Hooke, W. H.: Waves in the Atmosphere, Elsevier, New York, p. 98, 1975. Hirota, I. and Niki, T.: Inertia-gravity waves in the troposphere and stratosphere observed by the MU radar, J. Meteorol. Soc., Japan, 64, 995–999, 1986. Kuo, F. S., Lue, H. Y., Huang, C. M., Lo, C. L., Liu, C. H., Fukao, S., and Muraoka, Y.: A study of velocity fluctuation spectra in the troposphere and lower stratosphere using MU radar, J. Atmos. Terr. Phys., 54(1), 31–48, 1992. Kuo, F. S., Lue, H. Y., and Luo, C. L.: Physical parameters of gravity wave packet propagation contained in radar RTI plots., J. Atmos. Terr. Phys., 60(4), 455–460, 1998. Kuo, F. S., Röttger, J., and Lue, H. Y.: Propagation of gravity wave packets in the lower atmosphere observed by the SOUSY-Svalbard radar, Chinese J. Phys., 41(4), 309–325, 2003. Kuo, F. S. and Röttger, J.: Horizontal wavelength of gravity wave in the lower atmosphere measured by the SOUSY Svalbard Radar, Chinese J. Phys., 43(3-1), 464–480, 2005. Kuo, F. S., Lue, H. Y., and Fern, C. L.: Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes, Ann. Geophys., 25, 77–86, 2007. Kuo, F. S., Lue, H. Y., Fern, C. L., Röttger, J., Fukao, S., and Yamamoto, M.: Studies of vertical fluxes of horizontal momentum in the lower atmosphere using the MU-radar, Ann. Geophys., 26, 3765–3781, 2008. Manson, A. H. and Meek, C. E.: Gravity wave propagation characteristics (60–120 km) as determined by the Saskatoon MF Radar (GRAVNET) system: 1983–85 at 52° N, 107° W, J. Atmos. Sci., 45, 932–946, 1988. Meek, C. E., Reid, I. M., and Manson, A. H.: Observations of mesospheric wind velocities, 1. Gravity wave horizontal scales and phase velocities determined from spaced wind observations, Radio Sci., 20, 1363–1382, 1985. Nakamura, T., Tsuda, T., Yamamoto, M., Fukao, S., and Kato, S.: Characteristics of gravity waves in the mesosphere observed with the middle and upper atmosphere radar, 2. Propagation Direction, J. Geophys. Res., 98(D5), 8911–8923, 1993. Sato, K.: A statistical study of the structure, saturation and sources of inertia-gravity waves in the lower stratosphere observed with the MU radar, J. Atmos. Terr. Phys., 56, 755–774, 1994. Thomas, L., Worthington, R. M., and McDonald, A. J.: Inertia-gravity waves in the troposphere and lower stratosphere associated with a jet stream exit region, Ann. Geophys., 17, 115–121, 1999. Tsuda, T., Sato, S., Yokoi, T., Inoue, T., Yamamoto, M., VanZandt, T. E., Fukao, S., and Sato, T.: Gravity waves in the mesosphere observed with the MU radar, Radio Sci., 26, 1005–1018, 1990. Vincent, R. A. and Fritts, D. C.: A climatology of gravity wave motions in the mesosphere region of Adelaide, Australia, J. Atmos. Sci., 44, 748–760, 1987. Vincent, R. A. and Reid, I. M.: HF Doppler measurements of mesospheric gravity wave momentum fluxes, J. Atmos. Sci., 40(5), 1321–1333, 1983. Yamamoto, M., Tsuda, T., and Kato, S.: Gravity waves observed by the Kyoto meteor radar in 1983–1985, J. Atmos. Terr. Phys., 48, 597–603, 1986. Yamanaka, M. D., Fukao, S., Matsumoto, H., Sato, T., Tsuda, T., and Kato, S.: Internal gravity wave selection in the upper troposphere and lower stratosphere observed by the MU radar: preliminary results, Pure Appl. Geophys., 130, 481–495, 1989.