Royal Netherlands Meteorological Institute
Section of Atmospheric Composition
During a coordinated campaign devoted to wave-turbulence interactions, measurements with the high vertical resolution PROUST radar and radiosoundings have been performed in an upper level potential vorticity anomaly. This campaign took place during September 1996 at St. Santin, France, (44 degr 39 ' min N, 2 degr 12 ' E), where the radar is located. Radiosonde data reveal, along the eastern part of the anomaly, the presence of a saturated wave field, while the radar observes turbulent activity in regions of wave-induced wind shears. Characteristic parameters of the waves determined from the radar and radiosondes are generally in good agreement with the saturation onset conditions provided by linear saturation theory. The predicted relationship between vertical wavelength, period and energy dissipation rate proposed by the saturated-cascade theory is also found, although the proportionality factor is smaller than foreseen. When approaching the jet stream region, modulation by the wave field of the background wind shear gives rise to Kelvin-Helmholtz instabilities whose convective billows are observed by the radar.
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