|RADAR REFLECTIVITY PITFALLS
METEOROLOGIST JEFF HABY
Below is a list and explanation of radar reflectivity pitfalls:
1. Earth's curvature- The Earth's curvature causes more of a storm to be unsampled the further the storm
is from the radar site. This makes it more difficult to detect accurate VIL values and mesocyclonic
circulations at long ranges from the radar.
2. Topography- Elevated terrain can increase
ground clutter and
anomalous propagation. Valley regions
are not sampled if the radar is on the other side of elevated terrain.
3. Unusual temperature gradients- Strong
inversions and other strong temperature lapse rates will
refract the radar beam atypically. This will result in echo height errors, can increase ground clutter
in the case of inversions, and can causes sampling errors of storms.
4. Ground clutter- Overestimates precipitation intensity for echoes near the radar site. Ground clutter
will be reduced by using a higher tilt angle. Ground clutter also tends to be less when the lower
troposphere is unstable.
5. Beam spreading- The resolution of range gates decreases as range from the radar increases. Precipitation
areas will look bigger and pixilated at the longer ranges.
6. Attenuation- Radar beam is less powerful as it moves into the longer ranges from radar as the radar
beam moves through precipitation areas that scatter away the beam progressively as it moves away
from the radar. This causes an underestimation of echo intensity at the long radar ranges.
7. Unsampled regions- The cone of silence (cone created immediately above radar bounded by rotating
highest tilt angle used 360 degrees) is not sampled. The regions below lowest tilt angle is also
8. Location of precipitation- Position of precipitation aloft may not be position precipitation
strikes the Earth's surface.
9. Virga- Often much of the light precipitation that shows on radar
evaporates before reaching the ground.