Abstract. We describe a technique to detect gravity wave packets in high-resolution radiosonde soundings of horizontal wind and temperature. The vertical profiles of meridional and zonal wind speeds are transformed using the Morlet wavelet, and regions of high wind variance in height-wavenumber space are identified as gravity wave packets. Application of the Stokes parameter analysis to horizontal wind and temperature profiles of the reconstructed wave packets yields the wave parameters. The technique was applied to twice-daily radiosonde launches at Macquarie Island (55øS, 159øE) between 1993 and 1995. A strong seasonal cycle in the total wave variance was found, with a maximum in winter. The amount of wave energy propagating downward from the upper stratosphere also maximized in winter. Waves propagated predominately toward the southwest in winter, but in summer propagation directions were approximately isotropic. The intrinsic frequencies were close to the inertial frequency, and the waves had inferred horizontal wavelengths of several hundred kilometers.

Abstract. We calculate the mean-flow accelerations due to gravity wa.ve packets observed in the lower stratosphere over Macquarie Island (55øS, 159øE) between February 1994 and April 1995. The parameters of the wave packets were extracted from twice-daily radiosonde soundings using a wa. velet-based analysis method introduced by Zink and Vincent [this issue]. The deduced wave parameters are used to directly compute momentum flux profiles in the lower stratosphere, and the shortcomings of this approach to assess mean-flow accelerations axe discussed. We then use the observed wave packets as an input spectrum in a linear ray-tracing model. The vertical extent of the detected wave packets allows us to define an expression for wave intermittency, which enables us to compute zonal accelerations in the stratosphere and mesosphere. In the stratosphere the waves produce acceleration of the mean flow, in accordance with predictions. In the mesosphere the inferred wave drag is 2-3 times larger than previous observational and theoretical estimates.

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Abstract.The development of a novel VHF radar designed to measure winds and temperatures in the planetary boundary layer is described. The radar operates at 54.1 MHz and is compact and easily transportable. The antenna system consists of 12 Yagis grouped into three subarrays arranged in the form of an equilateral triangle. Transmission takes place on the whole array, and reception takes place on the three subarrays, with winds measured by the spaced antenna technique over a height range between 300 and 3000 m. Results from field trials conducted in southern Australia in a variety of meteorological conditions are presented. Comparisons with high-resolution radiosondes launched from the radar site show excellent agreement, with rms differences between radiosonde and radar wind components being about 1.5 m s -1. Observations carried out in rain show that echoes from precipitation are clearly distinguishable from clear-air echoes. Unlike UHF radars, this means that vertical air velocities can be measured during precipitation, and the evolution of drop-size distributions can be studied down to low altitudes. It is shown that temperatures derived from a radio acoustic sounding system are measured up to heights near 2 km, depending on background wind conditions.