Global-scale tidal variability during the PSMOS campaign of June-August 1999: interaction with planetary waves
During the PSMOS Global-scale tidal variability experiment campaign of June 1-August 31, 1999, a network of radars made measurements of winds, waves and tides in the mesosphere/lower-thermosphere region over a wide range of latitudes. Clear evidence was found that fluctuations in tidal amplitudes occur on a global scale in both hemispheres, and that at least some of these fluctuations are periodic in nature. Modulation of the amplitude of the 12 h tide was particularly evident at periods of 10 and 16 days, suggesting a non-linear interaction with planetary waves of those periods to be responsible. In selected cases, the secondary waves predicted from non-linear theory could be identified and their zonal wave numbers determined. In some, but not all, cases the longitudinal structure of the secondary waves supports the theory of planetary-wave/tidal interaction being responsible for the observed tidal modulation. It was noted also that beating between a 12.4-lunar and the solar tide could produce a near 16-day modulation of the 12 h tide amplitude that is frequently observed in late summer.
Authors: Pancheva, D., Merzlyakov, E., Mitchell, N.J., Portnyagin, Yu., Manson, A.H., Jacobi, Ch., Meek, C.E., Luo, Y., Clark, R.R., Hocking, W.K., MacDougall, J., Muller, H.G., Kürschner, D., Jones, G.O.L., Vincent, R.A., Reid, I.M., Singer, W., Igarashi, K., Fraser, G.I., Fahrutdinova, A.N., Stepanov, A.M., Poole, L.M.G., Malinga, S.B., Kashcheyev, B.L., Oleynikov, A.N.
1 January, 2002
Journal of Atmospheric and Solar-Terrestrial Physics / 64