User's Manual

Table Of Contents
ED 3100 G 110 / 02 (2011-10)
Operating Instructions
A-1 General Information
A RADAR.fm / 10.11.11
A-17
NACOS Platinum
Influences of Meteorological Processes
The influence of meteorological phenomena such as fog, rain, snow or hail on the radar video increases
with the size of the droplets in relation to the radar wavelength, and with the density of the droplets.
The shorter-wave X-Band radar (with a wavelength of 3 cm) is therefore generally impaired more
severely by meteorological influences than is the longer-wave S-Band radar (10 cm wavelength).
The following table describes the influences of rain and the influences on the radar:
Table A / 7 Influences of Meteorological Processes
In general, it is advisable not to use long pulse in rainy conditions and it is better to use the S-band
radar rather than the X-band. If no S-band radar is available, it must be considered that X-band radars
lose 50% of their coverage in heavy rains.
X-Band RADAR
Even in the X-Band radar, fog causes practically no disturbances, whereas precipitations with larger drop-
lets attenuate the transmitted radar pulses and thus weaken to a greater or lesser extent the display of
targets situated behind extensive areas of precipitation. Furthermore, throughout their entire extent, rain,
snow and hail reflect part of the transmitted energy and produce echoes in the form of milky areas in
the radar video (backscatter).
Because of the very different signal structures of useful targets and rain areas, rain clutter can be notice-
ably reduced by the rain clutter suppression function.
Reduction of target detection
S-Band,
short pulse
S-Band;
long pulse
X-Band,
short pulse
X-Band,
long pulse
Rain, 4mm/h, close range < 5nm Slightly Severely Slightly Severely
Rain, 4mm/h, medium range Nearly none Up to half Slightly Severely
Rain, 4mm/h, long range > 10nm Nearly none Slightly Slightly Severely
Rain, 16mm/h, close range < 5nm Slightly Severely Up to half Severely
Rain, 16mm/h, medium range Nearly none Severely Up to half Severely
Rain, 16mm/h, long range > 10nm Nearly none Severely Up to half Up to half