12.07.2015 Views

Proceedings with Extended Abstracts (single PDF file) - Radio ...

Proceedings with Extended Abstracts (single PDF file) - Radio ...

Proceedings with Extended Abstracts (single PDF file) - Radio ...

SHOW MORE
SHOW LESS
  • No tags were found...

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Following these early observations the two extreme cases, scattering from isotropic turbulenceand partial reflection from steep refractive index gradients, attracted wide attention. Thegoverning parameters, turbulence refractive index structure constant, determining the radarreflectivity η, and the reflection coefficient ρ were treated in many publications (see insetabove). It soon was recognized that the real atmosphere is not behaving properly enough toallow description of the MST VHF radar echoing mechanism by these two parameters. Thewhole issue is much more complicated, and is not even finally solved yet.SOUSY VHF Radar at AreciboFig. 2 (a) The left-side shows echo power differences between vertical and offverticalbeam measured <strong>with</strong> the MU Radar; (b) the right-side shows powerspectra of vertical to 10 degrees off-vertical bema pointing, measured <strong>with</strong> theSOUSY VHF radar at the Arecibo Observatory.It was also shown, that there are very thin layers (then called sheets or laminae) of echo power,which usually cannot be resolved by the best available standard range resolution of 150 m.Fig. 3 shows an example. A technique of pulse scanning and complex de-convolution wasimplemented (Röttger and Schidt, 1979), which allowed to estimate the thickness of sheets;some of these were only several tens meters thin.Intermediate summary: How can these VHF radar observations of thin sheets, which arehighly anisotropic, persistent and not immediately turbulent, and also the broader moreturbulent layers be explained properly by atmospheric processes?450

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!