PPI : Antenna Rotates in AZ Every Given EL Frequency Echo Frequency 2 Antenna wind Precipitation Transmitter & Receiver Processor Display Echo Intensity Doppler Velocity Spectrum Width & Various Products
100km 10km 1km 100m 10m 1m 10cm 1cm 1mm 0.1mm 3kHz 30kHz 300kHz 3MHz 30MHz 300MHz 3GHz 30GHz 300GHz 3THz
Band Designation Frequency Wave Length VHF 30 300 MHz 10 1 m UHF 300 1000 MHz 1 0.3 m L 1 2 GHz 30 15 cm S 2 4 GHz 15 8 cm C 4 8 GHz 8 4 cm X 8 12 GHz 4 2.5 cm K u 12 18 GHz 2.5 1.7 cm K 18 27 GHz 1.7 1.2 cm K a 27 40 GHz 1.2 0.75 cm Wind Profilers (6m, 75cm, 22cm) Radars for Precipitation (10,5,3 cm) Radars for Cloud or Fog (9mm, 3mm)
Modulator TX Control Unit TX Power Supply Local Control Unit Antenna Control Unit Klystron tube + Solenoid Radar Control Processor Klystron tank RX Power Supply Receiver RF Unit Radar Signal Processor
Pedestal Elevation Assembly Radome Antenna Azimuth Assembly Waveguide Assembly Riser Assembly
Antenna System Local Maintenance TX Pulse Transmitter Klystron/ Magnetron Control, BITE Antenna Control Unit TX+RX Angle Tags RX Signal TX Ref Receiver Radar Signal Processor RF Pulse Sample Raw Data, Control Setup, BITE Remote Maintenance Raw Data Control BITE Met System Control BITE Radar Control Processor
Bin volume Volume Scan Azimuth Z N Range Ray Elevation Elevation Step Beam width gate size W E S
side lobe 60 km Main lobe 1 km 3dB beam width (ex: 1 degree) 2 km 120 km
Radar beam relative to a flat earth
6 DnDdD ( ) vol Zradar = Vol ( Vol at 1~2Km aloft ) Z radar = a R b gauge π R 3 gauge = ρ DvD i ( i ) nd ( i ) D 6 Di D D max min R( x, y, t) = 3 DvDnD ( ) ( )( x, ytdd, )
Pre-cold frontal line or broad TSTM Small scattered cells Broad stratified rainbands Diffused echoes from TSTM Small cells along cold front Raindrop camera (Jones, 1959) Isolated TSTM
A Early classification of Z-R by rainfall types (Fujiwara, 1965) Thunderstorms Z = AR b Rain Showers Continuous Rain b
UHF profiler reflectivity on 1 May 1994 From disdrometric data collocated with the UHF profiler
Correlation coefficient 1 0.8 0.6 0.4 0.2 Central Florida Central adjusted Florida Courtesy of W. Krajewski light rain heavy rain 0 0 1 2 3 4 5 6 7 Gauge separation distance (km)
Is it all rain? BEAM BLOCKAGE Z e Birds taking advantage of the good winds. Identify and eliminate GROUND CLUTTER
Drop deformation? Beam broadening Height increase Range Effects Wet-radome Attenuation Measurement noise in Z, K DP, Z DR Radar calibration Instrumental Error Strong attenuation by precipitation at C-band DSD variability: Z, Z h,v, K DP, Z DR R Methods of deriving R-(Z,Z h,v,k DP,Z DR )relationships
Z (dbz) ϕ DP (deg) Z DR (db) K DP from ϕ DP
Model validation Radar data collection QPE: Error structure Retrieval/analysis of atmospheric state External data: satellite, mesonet, Numerical prediction Forecasting and Nowcasting algorithms: Severe weather detection, Hydrology, etc. USERS
Select a radar network Geographical Factor Coverage/ Occultation Radar range/ Beam level/ NO Preliminary Investigation of possible radar sites Geographical Geographical Factor Factor Check Check Flood Management Factor(FMF) - Population Density Index - Economic Density Index - Flood Damage Index - Prob. Rainfall Index FMF FMF Check Check!!!! Select radar types NO Site Feasibility Factor - vicinity/ civil work - electric interference - other facilities NO Decision Decision of of Radar Radar Network Network
MAJOR FACTORS Geographical Factor Flood Management Factor Site Feasibility Factor Radar Configuration Factor ELEMENTS Radar Horizonal Coverage, Ground Clutter, Occultation Watershed Occupation Population Density Index Economic Density Index Flood Damage Index Probabilistic Flood Rainfall Index Road vicinity civil work site manned or unmanned Electric and electronic Interference Number of radar sites Location of radar sites Distance between radar sites Melting layer intersection Scanning strategy Radar hardware types Polarization Multiple radar sites Radome attenuation Radar wave length NEEDS DEM Watershed boundary map River network map Population density map Regional facility map Regional historical flood damage cost map Flood rainfall map with 100 yr return period By site investigation Investigation of other electric facilities at site Define possible radar configuration for the best radar rainfall observation
Radar simulation screen Radar Specification Cover range Location Type Elevation Antenna Height Beam angle Radar Occultation (%) Radar Watershed Coverage (%) Radar vertical projection map
Korea DEM Site Specification Elevation Antenna height Beam angle Radar coverage Geographical analysis Flood management factor analysis Radar Coverage and Occultation Base Maps
FMA (Flood Management Factor) = Weighted Sum of Areal Coverages for Flood-related indices for proposed Radar Networks in each watershed.