Asymmetry of atmospheric microstructure over synoptic scales

Abstract

Abstract. Distortions are often seen in the angular distribution of echo-power from VHF wind-profiling radars, suggesting that thin stable layers, within the air flow, are distorted and tilted from horizontal. In vertical shear of the horizontal wind, the distribution of the layer tilt angles becomes skewed. A case study using six days of VHF radar data and synoptic charts above western Europe indicates that this asymmetry of atmospheric microstructure can exist throughout the troposphere and lower stratosphere, above and below the jet wind maximum, over horizontal scales of thousands of kilometres.

Implementation and Validation of Range Imaging on a UHF Radar Wind Profiler

“…Observations have been made of persistent layers in the atmosphere attributed to both turbulence and sharp gradients in temperature and humidity (Dalaudier et al 1994;Muschinski and Wode 1998;Luce et al 2001a;Worthington 2001). In addition to being intriguing from a dynamical point of view, there is also interest in better understanding how such layers impact on radar backscatter (Luce et al 1995;Muschinski 1997;Muschinski and Wode 1998;Chilson et al 2001).…”

Aircraft measurements of asymmetric temperature microstructure causing azimuth variations of VHF radar echo power

“…The echo power distribution can vary with azimuth angle as well as zenith angle, for instance if aspect-sensitive scatterers are tilted by gravity waves (Gage et al, 1981;Muschinski et al, 1995;Hobbs et al, 2000;Worthington, 1999Worthington, , 2005, or the distribution of their tilt angles is asymmetric in wind shear (Worthington and Thomas, 1996;Worthington et al, 1999Worthington et al, , 2000Yamamoto et al, 2003). A possible cause of the asymmetry in wind shear is Kelvin-Helmholtz instability (KHI); however, asymmetry is observed in jet-stream wind shear through large volumes of troposphere and lower stratosphere (Worthington, 2001); KHI could occur so extensively (Muschinski, 1996) or only in patches (Klostermeyer and Ru¨ster, 1981).…”