- Good, useable data is often
collected in "clear-air"
conditions, i.e., in the absence of clouds and
- Originally, "clear-air" echoes were called "angel", or "ghost" echoes
- There are two possible scattering
1) Scattering from refractive index gradients on scale of l/2
- This is often referred to as
- for Bragg
- This suggests using long
wavelengths to more effectively detect refractive
index gradients - this is essentially what a
profiler is doing, remember, the profiler
wavelengths are quite large
2) Particulate scattering
from insects and birds
- Then have rayleigh scattering where
scattering mechanism is still somewhat of a matter of
debate, though the growing consensus is that most
clear-air data is scattering from insects.
So, why do you get areas of enhanced
clear-air echoes that appear to be some what linear????