G. Delrieu et al., SIMULATION OF RADAR MOUNTAIN RETURNS USING A DIGITIZED TERRAIN MODEL, Journal of atmospheric and oceanic technology, 12(5), 1995, pp. 1038-1049
The aim of the present study is to characterize mountain returns measu
red with a ground-based weather radar operating in a mountainous regio
n. A computation code based on the use of a digitized terrain model is
developed for calculating the areas illuminated by the radar beam. Pa
rtial and total screening effects are accounted for in the calculation
. The angular and range weighting functions of the radar measurement a
re modeled using Gaussian approximations to give the so-called weighte
d illuminated areas for various sizes of the radar resolution volume.
Radar measurements are compared to the computed illuminated areas in o
rder to determine the average backscattering coefficient of partly gra
ss-covered, partly forested mountains: 87% of the measured time-averag
ed mountain return variance is explained by the computed values when t
he 15-dB resolution volume is considered. Additional geometrical infor
mation, provided by the calculated angles of incidence, is accounted f
or to yield a linear sigma((dB))(0)(alpha) model relevant for the so-c
alled near-grazing region since most of the angles of incidence are in
the 70 degrees-90 degrees range. Here 92% of the measurement variance
is explained when the sigma((dB))(0)(alpha) model is used.