Radar: WSR-98D
The WSR-98D Weather Radar System is a version of WSR-88D manufactured by
METSTAR, China. It generates NEXRAD products. Information are available on web.
Abbreviations:
RDA = Radar Data Acquisition = Radar equipment including the signal processor and the radar control computer
RPG = radar product generator
VCP = Volume coverage Pattern, the scan strategy
S band, full coherent (klystron)
Pulse width = 1.57 microseconds
We use the VCP21 (Volume Coverage Pattern) scan strategy.
Data corrections:
Clutter removal
Available products for flash flood issues:
Base products: R (reflectivity), V (Velocity), W (spectrum Width) similar to PPIs (cuts at constant elevations)
Elevations:=0.5, 1.5, 2.4, 3.4, etc.
Reflectivity range: 5 to >75 dBZ approx. 6 minutes between scans polar products: 1degree, 1 km
Rainfall Accumulation products:
generated by the Nexrad Precipitation algorithm; the software selects the source data
(range, elevation) to measure at low heights, to minimize occultation and to mitigate
Abnormal Propagation, etc.
Z=200R^1.6, R is limited (capped) at 103 mm/h.
polar products, 1 degree, 2 km.
OHP (One Hour Precipitation): accumulation in the last 60 minutes; updated each
VCP (aprox. 6 minutes), 16 levels (ND +14 intervals + 1 “>= “interval ) data
THP (Three Hours Precipitation): accumulation in the last three hours, starts at
HH:00, ends at HH+3:00, generated each VCP (6 minutes) but updated only once per hour (in one hour, RPG generates about 10 maps containing the same data, only the time stamp is different), 16 levels data.
STP (Storm Total Precipitation): Accumulation ends if no rain is detected during one hour. RPG resets and technical interrupts reset the accumulation (new storm accumulation starts). Updated each VCP (aprox. 6 minutes.)
Other useful products:
composite reflectivity (column max), rectangular grid, 2x2 , 4x4 km
Storm Tracking Information (symbols, lines, table)

Storm Structure (table)
Mezo cyclone detection (symbols, table)
Hail Index (symbols, tables)
Remarks:
1. NO rain rate products are available
The product: Hybrid Scan Reflectivity is a digital, polar array, containing reflectivity used for Z->R conversion.
2. File formats are available; we may develop software for offline processing (compute accumulation on different time intervals, search for maximum, etc.).
Radar Data
Reflectivity: 5 – 75 dBZ, 16 levels
PPI: elevations: 0.5, 1.5, 2.4, 3.4 deg.
Column maximum
Accumulated Precipitation
one hour, 16 levels, not linear three hours, 16 levels, not linear
Resolution: time (minutes)
6 minutes
6 minutes
6 minutes
60 minutes
(1 hour)
Resolution: space (km)
1 deg. x 1 km (polar)
2 x 2, 4 x 4 km (Cartesian)
1 deg. x 2 km (polar)
1 deg. x 2 km (polar)