Abstract
Abstract. Tidal activity in the Mesospheric Lower Thermosphere (MLT) region over Trivandrum (8.5° N, 77° E) is investigated using the observations from newly installed SKiYMET Meteor Radar. The seasonal variability and vertical propagation characteristics of atmospheric tides in the MLT region are addressed in the present communication. The observations revealed that the diurnal tide is more prominent than the semi/terdiurnal components over this latitude. It is also observed that the amplitudes of meridional components are stronger than that of zonal ones. The amplitude and phase structure shows the vertical propagation of diurnal tides with vertical wavelength of ~25 km. However, the vertical wavelength of the semidiurnal tide showed considerable variations. The vertical propagation characteristics of the terdiurnal tide showed some indications of their generating mechanisms. The observed features of tidal components are compared with Global Scale Wave Model (GSWM02) values and they showed a similar amplitude and phase structure for diurnal tides. Month-to-month variations in the tidal amplitudes have shown significant seasonal variation. The observed seasonal variation is discussed in light of the variation in tidal forcing and dissipation.
Highlights
Atmospheric tides are the strongest perturbations that play a decisive role in controlling the dynamics of the Mesospheric Lower Thermosphere (MLT) region
Atmospheric tides are the strongest perturbations that play a decisive role in controlling the dynamics of the MLT region
The horizontal wind observations from the radar system are used for the tidal analysis and to study its seasonal variability. These are the initial results from the radar observations, which are compared with GSWM02 (Hagan and Forbes, 2002, 2003) model values
Summary
Scale Mesopause Observing System (PSMOS) campaign has been carried out (Pancheva et al, 2002). The horizontal wind observations from the radar system are used for the tidal analysis and to study its seasonal variability These are the initial results from the radar observations, which are compared with GSWM02 (Hagan and Forbes, 2002, 2003) model values. Studies over Christmas Island showed meridional winds for three consecutive days, i.e. from 1 to s (72 hours).3Red contours represents the southerly winds and green the northerly that during April, May and June the growth of the zonal wind. The wind contours tilt downward consistent with model values except for June, July and April These phase profiles are used to estimate the vertical wavethe wave energy, which is more clear in the case of merid lengths, which are found to be ∼25 km. Consistent with that of the (1,1) mode of the migrating diurnal tidal component (Forbes and Groves, 1987)
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