Real time display
Image created for each scan of the radar as well as the software process that creates
these images.
RhoH and RhoV
The magnitude of the correlation between the co-and cross-polarized channels in a
dual channel receiver polarization radar operating in fixed or alternating H and V
transmit mode.
RhoHV
Correlation Coecient. The magnitude of the correlation between the HH and VV
channels of a dual polarization radar operating in STAR mode or switching mode in
the range [0,1]. Rain values are typically > 0.98. Wet tumbling hail has smaller values.
This value is useful in helping to identify the particle type.
SHEAR product
Used to identify microburst, gust fronts, cold fronts, and atmospheric waves. SHEAR
calculates the radial wind shear in the radial direction and is sensitive to atmospheric
convergence and divergence.
SLINE product
Short for "Shearline". Used to identify a front and fitting a line to it. It looks for
elongated regions of high shear and connects them to make a line.
STAR mode
Simultaneous Transmit And Receive. The operational mode of a dual polarization
radar where the radar transmits simultaneously horizontally and vertically.
Signal Quality Index (SQI)
The autocorrelation of the received signal at lag 1 divided by lag zero. This is a number
in the range [0,1] where 1 is the perfect Doppler point target and 0 is white noise.
Typically used for thresholding velocity and width at a level of ~0.3...0.4.
Signal processor
A programmable device for digitizing and processing video signals from the radar
receiver.
Spectrum Width (W)
Standard deviation of the Doppler spectrum displayed in m/s. Large width values
indicate high turbulence and/or shear in the pulse volume. It is dicult to measure the
spectrum width when the spectrum width is more than 1/3 of the total Nyquist interval
because of uncertainty in the estimator for broad spectra.
TOPS product
PPI format display of the height of a selectable dBZ echo contour.
TRACK product
Interactive tracking product made. After the operator tags echo features, IRIS inserts
points in a track and extends the track to show the forecast echo motion for a
selectable time.
Task
A set of instructions to the radar and signal processing systems including, but not
limited to, the scan type (PPI or RHI), PRF, pulse width, signal processing data types,
time and range averaging criteria. For example, a PPI volume scan at multiple
elevation angles or an RHI at a single azimuth. Also called radar task.
IRIS User Guide M211317EN-E
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