Vaisala IRIS - Page 27

Data type Description
PHIH, PHIV Horizontal (V) or vertical (V) dierential phase
Phase dierence for the total round trip between radar and the volume where
the signal is reflected. PHIH is measured between HH and HV channels. PHIV
is measured between VV and VH channels.
PHIDP
Dierential phase
The phase dierence due to propagation between the HH and VV channels of
the radar.
PMI
Polarimetric meteo index.
R
Rate of accumulation of precipitation in units of mm/hour. For snow, this is
usually refers to the liquid equivalent.
RHOHV, RHOH, RHOV Correlation coecient between HH and VV (or HH & HV / VV & VH) channels )
Higher (>0.95) values indicate uniform precipitation areas and lower values
more mixed hydrometeor types, such as melting snow, wet snowflakes, or
airborne debris.
SNR
Signal to Noise Ratio
Generic measurement of signal-noise ratio in dB.
SQI
Signal Quality Index
A value between 0-1 that measures the signal's Doppler coherency, that is the
correlation between the signal and its Doppler lag.
• 0 indicates white noise
• 1 is the perfect Doppler point target
T
Total Reflectivity
Total power returned to the radar in reflectivity units. It typically represents
the horizontal reflectivity without ground clutter correction.
TV, TE Total Vertical (HV Enhanced) Reflectivity
Total reflectivity from the vertical polarization channel (TV) and combination
of the horizontal and vertical channel (TE).
V
Velocity
Average radial velocity (towards or away from the radar) of detected
hydrometeor areas.
VC
Corrected Velocity
Same as Velocity, but corrected for eects of range folding and velocity
folding.
V: SHEAR, Vc: SHEAR Velocity and corrected velocity of wind shear.
W
Spectral Width
Variability of Doppler velocity values within the measurement area.
XCOR
Polar cross-correlation, uncorrected rhohv. Because this value is not noise
corrected, it is a direct indicator of the PHIDP uncertainty
Z
Reflectivity
Usually referred to as dBZ, this is the common data type that measures radar
signal reflectivity, and is used to estimate precipitation intensity from that.
All Z measurements are corrected for ground clutter.
Chapter 3 – Configuring IRIS Products
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