RadarRadar BasicsBasics Strengths,Strengths, LimitationsLimitations andand MythsMyths 2009 DuPage County Advanced Spotter Training Wheaton College Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training RadioRadio DetectionDetection andand RangingRanging NEXRADNEXRAD – – Next Next Generation Generation Radar Radar WSR-88DWSR-88D – – Weather Weather Surveillance Surveillance Radar, Radar, 1988 1988 Doppler Doppler Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training ImportantImportant AnglesAngles The azimuth angle is the compass angle from north (360°) Targets are indicated by A/R (Azimuth/Range) Birds eye view is displayed on a PPI (Planned Position Indicator) A cross sectional display is an RHI (Range Height Indicator) Volume scan Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 1 ReflectivityReflectivity Reflectivity is a measure of how much power is returned from a radar’s pulse. The information is displayed in pixel-like units of area called “gates” The unit of reflectivity is a decibel of reflectivity or dBZ. Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training ClearClear AirAir ModeMode RangeRange from from -28 -28 to to 28 28 dBZ dBZ 1616 4dBz 4dBz increments increments Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training PrecipitationPrecipitation ModeMode RangeRange from from 5 5 to to 75 75 dBZ dBZ 1616 5dBz 5dBz increments increments Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 2 ModeMode isis ControlledControlled byby NWSNWS andand CanCan BeBe ProblematicProblematic Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training NIDSNIDS --Nexrad NexradInformation Information DisseminationDissemination ServiceService BaseBase Reflectivity Reflectivity – – Various Various Elevation Elevation Angles Angles Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training NIDSNIDS --Nexrad NexradInformation Information DisseminationDissemination ServiceService BaseBase (or (or Storm Storm Relative) Relative) Velocity Velocity – – VariousVarious Elevation Elevation Angles Angles Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 3 NIDSNIDS --Nexrad NexradInformation Information DisseminationDissemination ServiceService 11 Hour Hour Precipitation Precipitation Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training NIDSNIDS --Nexrad NexradInformation Information DisseminationDissemination ServiceService StormStorm Total Total Precipitation Precipitation Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training NIDSNIDS --Nexrad NexradInformation Information DisseminationDissemination ServiceService Composite Reflectivity Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 4 InterpretingInterpreting DopplerDoppler RadarRadar RadialRadial Velocity Velocity is is the the velocity velocity toward toward or or away away from from a a radar radar Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training AutomatedAutomated DetectionDetection ofof MeteorologicalMeteorological PhenomenaPhenomena Algorithms help detect significant features • MDA – Mesocyclone Detection Algorithm • Meso - “donut” • Persistent, strong and detected over a large depth of the storm • TDA – Tornado Detection Algorithm • TVS – Tornado Vortex Signature • Strong gate to gate shear • HDA – Hail Detection Algorithm SCIT - Storm Cell Identification and Tracking Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training CompositeComposite ReflectivityReflectivity withwith StormStorm AttributeAttribute TableTable Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 5 CompositeComposite ReflectivityReflectivity withwith SymbolsSymbols Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training VelocityVelocity AliasingAliasing andand DealiasingDealiasing Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training APAP andand GroundGround ClutterClutter AP is enhanced by strong returns from buildings (ground clutter) Cooling in the evening hours results in a low-level nocturnal inversion and AP Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 6 MythMyth 1:1: AllAll StormsStorms areare SupercellsSupercells (Wouldn(Wouldn’t’t thatthat bebe nice!)nice!) Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training MythMyth 2:2: II CanCan IdentifyIdentify SupercellsSupercells byby LookingLooking atat ReflectivityReflectivity 1 2 3 4 5 WhichWhich are are supercells? supercells? Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training MythMyth 3:3: SizeSize MattersMatters Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 7 MythMyth 4:4: SupercellsSupercells areare IsolatedIsolated StormsStorms Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training TruthTruth 1:1: AlwaysAlways UseUse VelocityVelocity DataData toto DetectDetect thethe MesocycloneMesocyclone Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training MythMyth 5:5: RedRed NextNext toto GreenGreen MeansMeans RotationRotation Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 8 TruthTruth 2:2: AzimuthalAzimuthalShear Shear ImpliesImplies RotationRotation Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training AA TVSTVS isis StrongStrong ““Gate-to-Gate”Gate-to-Gate” AzimuthalAzimuthalShear Shear Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training TVSTVS Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 9 BiggestBiggest RadarRadar MythMyth Ever!Ever! RadarRadar WillWill SeeSee AllAll TornadoesTornadoes Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training MostMost ImportantImportant Truth:Truth: SpottersSpotters areare VitalVital ToTo SuccessSuccess Radar is a very powerful tool It helps meteorologists understand what might be happening in the storm Only a good spotter can verify that info Radar is prone to a lot of errors and mistakes in interpretation Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training WhereWhere toto GetGet RadarRadar InfoInfo http://weather.cod.edu/analysis http://radar.weather.gov/ http://grlevelx.com/ Other private vendors Professor Paul Sirvatka – College of DuPage 2009 DuPage Advanced Spotter Training 10.