Dual polarization systems use the enhanced reflectivity Ze along with a large number of
processed samples to significantly improve the sensitivity when compared with single
polarization systems. Samples are collected from a large contributing area using a wider
azimuthal spacing of the radar rays (2°) and a range averaging over several consecutive
range bins.
The default configuration has a maximum range of 450 km. Use it in warm climates. In
cooler climates, lower the maximum range to, for example, 350 km in summer or 250 km in
winter. Shorter ranges allow for higher pulse repetition frequencies (within the range) and
more pulses can be
configured within the constant run time.
The LOG threshold is optimized for tropical conditions with a clear margin of noise
uncertainty, even in conditions of extreme rain. In cooler climates, with a calibrated radar,
the LOG threshold can be as low as 1.2 dB.
The following
figure shows the task configuration details for a dual polarization system. Blue
circles indicate items with
dierent values in single polarization systems.
Azimuth Resolution 1.00°
Polarization Horiz
Samples 35
DP Attn Cor Z ZDR disabled
Range Avg/Smt
Proc Mode FFT
Measured data moments T, Z, Vel, Width, SQI
Figure 25 SURVEILLANCE Task Configuration -Dual Polarization
A.1.2. VOL_A
The VOL_A task is the lower part of the hybrid volume scan VOL_A and VOL_B. It is
optimized for precipitation observations and measurements within a range of 250 km. Use a
single pulse repetition frequency mode for the maximum quality of Z and dual polarization
moments.
Dual polarization systems use the enhanced reflectivity Ze to improve sensitivity. The Z data
fields are quality-controlled for maximum rejection of non-meteorological echo. The Z data
presents the true fields of precipitation. The combined observations of KDP and Z are used
in quantitative rainfall estimates.
In dicult conditions with moving clutter, sea clutter, and interference, you can raise the PMI
threshold to as high as 0.55. Try a higher SQI value with some loss of precipitation in the
melting layer and in strong convection.
The following
figure shows the configuration details of the task for a dual polarization
system. Blue circles indicate items with dierent values in single polarization systems.
IRIS User Guide M211317EN-E
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