Differential Reflectivity
- Raindrops are not always spherical
when they fall - especially the larger drops
- They tend to become more oblate
-->>
- So, the reflectivity would be
larger if the wave were horizontally polarized,
or Z_{h}
> Z_{v}
- Define Z_{DR} =
differential reflectivity = 10 log (Z_{h}/Z_{v})
- Z_{DR} is great for
discriminating large drops from hail - hail
tumbles randomly, looks like a spherical
particle.
- Here
are typical Z_{DR} values for different
sized rain drops
- So, Z_{DR} for hail is
about 0.
- Z_{DR} for ice is about 0
as well.
Z_{DR} example for a summertime
thunderstorm:
Combining
ZDR and other multi-parameter variables with dBZe can tell us much about
the internal microphysical structure of storms
REQUIRED MATERIAL: 4. Dual-Pol Radar Products
at:
http://www.wdtb.noaa.gov/courses/dualpol/index.html |