Physics – Atmospheric and Oceanic Physics
Scientific paper
2005-05-11
Physics
Atmospheric and Oceanic Physics
17 pages 9 figs submitted to Q. J. Roy. Met. Soc
Scientific paper
The radar scattering properties of realistic aggregate snowflakes have been calculated using the Rayleigh-Gans theory. We find that the effect of the snowflake geometry on the scattering may be described in terms of a single universal function, which depends only on the overall shape of the aggregate and not the geometry or size of the pristine ice crystals which compose the flake. This function is well approximated by a simple analytic expression at small sizes; for larger snowflakes we fit a curve to our numerical data. We then demonstrate how this allows a characteristic snowflake radius to be derived from dual-wavelength radar measurements without knowledge of the pristine crystal size or habit, while at the same time showing that this detail is crucial to using such data to estimate ice water content. We also show that the `effective radius', characterising the ratio of particle volume to projected area, cannot be inferred from dual-wavelength radar data for aggregates. Finally, we consider the errors involved in approximating snowflakes by `air-ice spheres', and show that for small enough aggregates the predicted dual wavelength ratio typically agrees to within a few percent, provided some care is taken in choosing the radius of the sphere and the dielectric constant of the air-ice mixture; at larger sizes the radar becomes more sensitive to particle shape, and the errors associated with the sphere model are found to increase accordingly.
Ball Robin C.
Field P. R.
Westbrook C. D.
No associations
LandOfFree
Radar scattering by aggregate snowflakes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Radar scattering by aggregate snowflakes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radar scattering by aggregate snowflakes will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-73818