radarmeteo data processing
 

hello to everybody.
this is a very technical question about weather radar data.
radar raw data are just voltage signatures (in phase and quadrature
components) which correspond to the electric field detected by the
radar receiver. At any instant the voltage (a phasor)
is the sum of the electric fields backscattered by the hydrometeors
present in a resolution volume of radial length of ct/2 where t is the
radar pulse width. (Doviak and Zrnic, pag 67, formula 4.1)
For weather radars and in particular for the radar i'm dealing with,
this radial length turns out to be about 200m. Being the radar
wavelength 5.5 cm, the hydrometeors should be irradiated with
different phases.
As there are so many hydrometeors present in a resolution volume and
when observing rain or thick clouds it is reasonable to think of a
uniform distribution within the resolution volume, the backscattered
phases
'should have a uniform distribution over the interval 0- 2pi'.
The backscattered electric field should be the sum of waves with
different
phases that should interfere destructively.
SO, WHY IS THERE AN ECHO??
Obviously, as THERE IS an echo there must be a mistake in the
reasoning above
and i would like to know where i'm going wrong.

Personally, i think i have a solution but i i'm not sure.
Thanks very much in advance to anyone who can help me.
Michele
ARPA - SMR, BOLOGNA ITALY