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Volume 51 Supplement 7-8

Special Issue: Dynamics and Structure of the Mesopause Region (DYSMER)

Spatial structure of the 12-hour wave in the Antarctic as observed by radar

Abstract

We present radar measurements of the 12-hour wave, a zonal wavenumber 1 westward propagating wave that exists in the southern polar mesopause region winds (Hernandez et al., 1993; Forbes et al., 1995). MF radar measurements of the horizontal winds at McMurdo (77.8°S, 166.67°E) show that the 12-hour wave is highly seasonal, occurring during the austral summer solstice. During these seasonal occurrences, the wave is highly intermittent with amplitude peaks of 30 m s−1. The burst-like occurrences of large 12-hour wave amplitudes are highly correlated between the zonal and meridional direction. The diurnal tide over McMurdo has a more constant amplitude, but it is also an almost exclusively summertime phenomenon. Inertia-gravity wave activity is evident at periods less than 12 hr during the austral winter months. The weakening of gravity wave activity during the summer is probably due to critical layer filtering by the zonal mean wind, 12-hour wave and diurnal tide which are all strong during this season. The 12-hour wave is confined in height to the vicinity of the zero crossing in the zonal winds above the westward jet. Extreme distortion is observed in the vertical phase fronts of the 12-hour wave which could signify either refraction or in situ forcing. The distortion in the phase fronts and localization of the 12-hour wave in time and height is apparently responsible for departures in period from the nominal 12 hours. We do not find the wave period to be systematically different from 12 hours. The association of the 12-hour wave events with shear in the mean wind suggests that refractive effects could conceivably cause a dilation in wave amplitude. However, the shear is of the opposite sign to cause this dilation unless the wave originates at higher altitudes and propagates downward into the mesosphere. Investigations are made of the zonal structure of the 12-hour wave by comparing phases of the 12-hour wind component between McMurdo and the dynasonde at Halley (75.8°S, 26.4°W). The phase is found to be stable and consistent with a westward propagating zonal wavenumber 2 structure during seasons when the 12-hour wave is weak. The migrating semidiurnal tide evidently dominates during these times of the year. During seasons when the 12-hour wave amplitude is large, the zonal structure is highly unstable and there is not an obvious dominant zonal wavenumber.

References

  1. Burrage, M. D., D. L. Wu, W. R. Skinner, D. A. Ortland, and P. B. Hays, Latitude and seasonal dependence of the semidiurnal tide observed by the high-resolution Doppler imager, J. Geophys. Res., 100, 11,313–11,321, 1995.

    Article  Google Scholar 

  2. Charles, K. and G. O. L. Jones, Mesospheric mean winds and tides observed by the Imaging Doppler Interferometer (IDI) at Halley, Antarctica, J. Atmos. Sol.-Terr. Phys., 61, 351–362, 1999.

    Article  Google Scholar 

  3. Dudeney, J. R., A. S. Rodger, A. J. Smith, M. J. Jarvis, and K. Morrison, Satellite experiments simultaneous with Antarctic measurements (SESAME), Space Sci. Rev., 71, 705–742, 1995.

    Article  Google Scholar 

  4. Forbes, J. M., N. A. Makarov, and Yu. I. Portnyagin, First results from the meteor radar at South Pole: A large 12-hour oscillation with zonal wavenumber one, Geophys. Res. Lett., 22, 3247–3250, 1995.

    Article  Google Scholar 

  5. Fritts, D. C. and J. R. Isler, Mean motions and tidal and two-day structure and variability in the mesosphere and lower thermosphere over Hawaii, J. Atmos. Sci., 51, 2145–2164, 1994.

    Article  Google Scholar 

  6. Fritts, D. C., D. M. Riggin, B. B. Balsley, and R. G. Stockwell, Recent results with an MF radar at McMurdo, Antarctica: Characteristics and variability of motions near 12-hour period in the mesosphere, Geophys. Res. Lett., 25, 297–300, 1998.

    Article  Google Scholar 

  7. Gill, A. E., Atmosphere-Ocean Dynamics, 662 pp., Academic Press, London, 1982.

    Google Scholar 

  8. Hernandez, G., R. W. Smith, and J. F. Conner, Neutral wind and temperature in the upper mesosphere above South Pole, Antarctica, Geophys. Res. Lett., 19, 53–56, 1992.

    Article  Google Scholar 

  9. Hernandez, G., G. J. Fraser, and R. W. Smith, Mesospheric 12-hour oscillation near South Pole, Antarctica, Geophys. Res. Lett., 20, 1787–1790, 1993.

    Article  Google Scholar 

  10. Hernandez, G., R. W. Smith, J. M. Kelley, G. J. Fraser, and K. C. Clark, Mesospheric standing waves near South Pole, Geophys. Res. Lett., 24, 1987–1990, 1997.

    Article  Google Scholar 

  11. Jones, G. O. L., K. Charles, and M. J. Jarvis, First mesospheric observations using an imaging Doppler interferometer adaptation of the dynasonde at Halley, Antarctica, Radio Sci., 32, 2109–2122, 1997.

    Article  Google Scholar 

  12. Papoulis, A., Signal Analysis, 431 pp., McGraw-Hill, New York, 1977.

    Google Scholar 

  13. Portnyagin, Yu. I., J. M. Forbes, G. J. Fraser, R. A. Vincent, S. K. Avery, I. A. Lysenko, and N. A. Makarov, Dynamics of the Antarctic and Arctic mesosphere and lower thermosphere regions—II. The semidiurnal tide, J. Atmos. Terr. Phys., 55, 843–855, 1993.

    Article  Google Scholar 

  14. Portnyagin, Yu. I., J. M. Forbes, N. A. Makarov, E. G. Makarov, E. G. Merzlyadov, and S. Palo, The summertime 12-hour wind oscillation with zonal wavenumber S = 1 in the lower thermosphere over the South Pole, Ann. Geophys., 18, 828–837, 1998.

    Google Scholar 

  15. Riggin, D., D. C. Fritts, T. Tsuda, T. Nakamura, and R. A. Vincent, Radar observations of a 3-day Kelvin wave in the equatorial mesosphere, J. Geophys. Res., 102, 26,141–26,157, 1997.

    Article  Google Scholar 

  16. Stening, R., K. Fleming, and G. Fraser, Upper atmosphere semidiurnal tides at Christchurch (44°S) and Scott Base (78°S), J. Atmos. Terr. Phys., 57, 857–869, 1995.

    Article  Google Scholar 

  17. Stockwell, R. G., L. Mansinha, and R. P. Lowe, Localization of the complex spectrum: The S transform, IEEE Trans. Signal Processing, 44, 998–1001, 1996.

    Article  Google Scholar 

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Correspondence to D. M. Riggin.

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Riggin, D.M., Fritts, D.C., Jarvis, M.J. et al. Spatial structure of the 12-hour wave in the Antarctic as observed by radar. Earth Planet Sp 51, 621–628 (1999). https://doi.org/10.1186/BF03353220

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Keywords

  • Radar
  • Zonal Wind
  • Austral Summer
  • Diurnal Tide
  • Semidiurnal Tide