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Ann. Geophys., 19, 933-944, 2001
www.ann-geophys.net/19/933/2001/
© European Geosciences Union 2001
The structure of turbulence in the middle and lower atmosphere seen by and deduced from MF, HF and VHF radar, with special emphasis on small-scale features and anisotropy
W. K. Hocking1 and J. Röttger2
1Dept. of Physics and Astronomy, University of Western Ontario, London, Ont. N6A 3K7, Canada
2Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, Germany
Abstract. An overview of the
turbulent structures seen by MF, HF and VHF radars in the troposphere,
stratosphere and mesosphere is presented, drawing on evidence from previous
radar measurements, in situ studies, laboratory observations, observations at
frequencies other than those under focus, and modelling studies. We are
particularly interested in structures at scales less than one radar pulse
length, and smaller than the beam width, and especially the degree of
anisotropy of turbulence at these scales. Previous radar observations are
especially important in regard to the degree of anisotropy, and we highlight
the role that these studies have had in furthering our understanding in this
area. The contrasts and similarities between the models of anisotropic
turbulence and specular reflection are considered. The need for more intense
studies of anisotropy at MF, HF and VHF is especially highlighted, since this
is an area in which these radars can make important contributions to the
understanding of atmospheric turbulence.
Key words. Meteorology and
atmospheric dynamics (turbulence) – Atmospheric composition and structure
(instruments and techniques) – History of geophysics (atmospheric sciences)
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