Abstract
Abstract. We present an experimental and modelling study of a strong gravity wave event in the upper troposphere/lower stratosphere near the Scandinavian mountain ridge. Continuous VHF radar measurements during the MaCWAVE rocket and ground-based measurement campaign were performed at the Norwegian Andoya Rocket Range (ARR) near Andenes (69.3° N, 16° E) in January 2003. Detailed gravity wave investigations based on PSU/NCAR Fifth-Generation Mesoscale Model (MM5) data have been used for comparison with experimentally obtained results. The model data show the presence of a mountain wave and of an inertia gravity wave generated by a jet streak near the tropopause region. Temporal and spatial dependencies of jet induced inertia gravity waves with dominant observed periods of about 13 h and vertical wavelengths of ~4.5–5 km are investigated with wavelet transform applied on radar measurements and model data. The jet induced wave packet is observed to move upstream and downward in the upper troposphere. The model data agree with the experimentally obtained results fairly well. Possible reasons for the observed differences, e.g. in the time of maximum of the wave activity, are discussed. Finally, the vertical fluxes of horizontal momentum are estimated with different methods and provide similar amplitudes. We found indications that the derived positive vertical flux of the horizontal momentum corresponds to the obtained parameters of the jet-induced inertia gravity wave, but only at the periods and heights of the strongest wave activity.
Highlights
Gravity waves are an essential part of the dynamics of the atmosphere on a wide band of meteorological scales
Similar to Worthington and Thomas (1996), we have reduced the influence of the mean winds and of the mountain waves by a Lanczos-low-pass filter which passes periods smaller than 36 h and vertical wavelengths less than 7 km to separate the estimated inertia gravity waves with vertical wavelengths of about 4–5 km in order to derive the wind perturbations u, v, w
From our analyses (Table 2) we found on 25 January a negative horizontal wave number and negative vertical group velocity corresponding to a downward energy propagation result, so that we can explain the derived positive vertical flux of the horizontal momentum in the zonal direction on 25 January from 12:00–24:00 UT between 6 and 8 km with the obtained wave parameters
Summary
Gravity waves are an essential part of the dynamics of the atmosphere on a wide band of meteorological scales. Generated gravity waves with upward propagation can be expected in the presence of strong winds in the lower troposphere. Such a meteorological situation is often coupled with strong winds in the tropopause level, which can be associated with sub-inertial waves generated from a jet in the tropopause region. This generation process has previously been shown to produces both upward and downward propagating waves (Peters et al, 2003). It is an important task to detect and quantify both mountain and jet generated inertia gravity waves
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
