VIL product
Vertically Integrated Liquid. Allows the operator to specify a layer in the atmosphere
and integrates the total liquid contained within the layer. The point estimates of the
liquid are based on a user-defined Z-W relationship.
VVP product
The velocity volume product calculates the vertical profile of the mean wind speed,
direction, divergence and deformation. The algorithm assumes a linearly varying wind
field and performs a least squares fit over a large volume surrounding the radar.
Vc
Velocity (V) corrected by IRIS for the eects of folding. Note that dual PRF velocity
unfolding performed by the processor is stored as V rather than Vc. Vc is used
primarily for dual Doppler wind field computation which requires unfolded velocities.
Velocity folding
Erroneous readings due to particles in the measurement area exceeding the maximum
velocity detection threshold of the radar system. The measured velocity "wraps
around" to the other end of the scale, resulting in discontinuous readings. Also called
velocity aliasing.
WARN product
Checks other products to determine if significant weather is present. The operator can
define the warning criteria and thresholds. The locations (centroids) of weather
features are also calculated.
WIND product
Uses the velocity volume algorithm to calculate a 2-D horizontal profile of the
horizontal wind speed and direction. The algorithm assumes zero vertical velocity and
a fixed wind field over a sub-region of the area covered by the radar.
XSECT product
A vertical slice through a volume scan. The product is similar to RHI except that it is
constructed from PPI data collected at multiple elevation angles.
Z (Reflectivity)
Z
H
- horizontal, Z
V
- vertical, Z
HV
-horizontal and vertical
Integral over the backscatter cross-section of the particles in a pulse volume.
Radars are calibrated to directly give the reflectivity factor from the received backscattered
energy. Units for the
reflectivity factor are mm 6 m-3. The logarithmic value is in dBZ.
ZDR
Dierential reflectivity (Z
dr
), the ratio between the reflectivity of a horizontal
polarized pulse and the reflectivity of a vertical polarized pulse, in dB.
ZDR depends on the asymmetry of the shape, the orientation, and the falling behavior of the
particles. ZDR is positive for oblate raindrops, zero or slightly negative for hail and graupel.
ZDR is strongly biased by
dierential attenuation during the passage of the radar pulse
through heavy rainfall.
Glossary
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