Intermediate-scale tropical inertia gravity waves observed during the TWP-ICE campaign

We describe a 2-day wave event observed in high-resolution radiosonde soundings of horizontal wind and temperature taken during the TWP-ICE experiment in Darwin area. The vertical profiles of temperature, zonal and meridional wind speeds are analyzed using the S-transform wavelet analysis. Results of the analysis reveal the presence of 2-day inertia gravity waves in the stratosphere between 20 and 27 km. The wave presents vertical and horizontal wavelengths of around 6 km and 7220 km respectively. The wave was observed to propagate southeastward during the end of the easterly phase of the QBO. The total vertical momentum flux associated with the waves is estimated to be 1 to 2.2 x 10(-3) m(2) s(-2). This is of the same order of magnitude as previous observations of 4-10 day Kelvin waves in the lower stratosphere.