Radar Palet e Home Radar Artifacts Analysis & Diagnosis 1 Radar Artifacts Radar Beam Filling Non Uniformity Of Vertical Distribution Of Precipitation Variations In Z-R Relationship Attenuation By Intervening Precipitation Beam Blocking Attenuation Due To A Wet Radome Electromagnetic Interference Ground and Other Clutter Anomalous Propagation Antenna Accuracy Electronics Stability Processing Accuracy Radar Range Equation

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 2 The Schematic Radar

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 3 Radar Sources of Error

Radar Palet e Home Radar Artifacts Radar System Limitations

Radar Palet e Home Radar Artifacts Non-meteorological effects

Radar Palet e Home Radar Artifacts Meteorological Effects

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 7 Radar sensitivity and blockage Not all radars are equal Most are retrofitted Enterprise radars with 1.1° beam width and 4 m dishes Some are Andrews radars with 0.65° beam width and 6 m dishes Spirit River AB, WWW, has only 1.6° beam width! Many have obvious issues –differences in sensitivity between each other –blockages But many have less obvious, but significant problems that only become apparent with long-term precipitation accumulations

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 8 15 Day Precip Accum CAPPI 1.5 km XSS 1829m WUJ 60m XSI 700m XPG 1118m WWW 1015m BC

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 9 30 Day Precip Accum PRECIPET Prairies

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 10 2 Day Precip Accum CAPPI 1.0 km Feb Nrn Ontario

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 11 2 Day Precip Accum CAPPI 1.0 km Mar Srn Ontario

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 12 2 Day Precip Accum CAPPI 1.0 km Mar Srn Quebec N

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 13 2 Day Precip Accum CAPPI 1.0 km Jan Atlantic

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 14 Sources of Error - Radar Dome Wetting

Radar Palet e Home Radar Artifacts Sources of Error Intervening precipitation Wet radome Beam blocking

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 16 Attenuation: What lies beyond?

Radar Palet e Home Radar Artifacts Foreground Storm Wedge of attenuation Example of Attenuation in Precipitation

Radar Palet e Home Radar Artifacts Cross Section constructed along this line

Radar Palet e Home Radar Artifacts 60 dbZ core

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 20 Sources of Error - Cell Blocking Cell blocking

Radar Palet e Home Radar Artifacts Spirit River, AB/BC BEAM BLOCKING ??? Persistent Ground clutter Beam blockage N Clear Hills S Rockies

Radar Palet e Home Radar Artifacts Foreground Storm Wedge of attenuation Attenuation

Radar Palet e Home Radar Artifacts Attenuation Warm Frontal Supercell

Radar Palet e Home Radar Artifacts Attenuation north end of derecho?

Radar Palet e Home Radar Artifacts Radome Wetting You just Checked The radar… NO PROBLEM… PROBLEM !

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 26 Sources of Error - Sidelobes 3D View of Real Beam Orographic Enhancement

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 27 Sources of Error - Blocking Impacts on Precipitation Estimates No PCPN? Why no precipitation amount maximum on the peaks?

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 28 Bright Band Melting snowflakes are large bright radar targets Reflectivity from melting snow is larger than that of the rain below or the snow above as falling snow passes through the melting layer Huge impact on quantitative precipitation estimates

Radar Palet e Home Radar Artifacts Bright band shows up as ring (or partial ring) of high Z centred on the radar Bright band

Radar Palet e Home Radar Artifacts Bright Band Freezing Level ~2.5km AGL Either associated with Rain or Freezing Rain Melting of Snow Flakes starts at 2.5 km height

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 31 Bright Band Time/height Display Time Melting Starts Melting

Radar Palet e Home Radar Artifacts But not on the lower elevation scan, in this case

Radar Palet e Home Radar Artifacts Melting layer shows as peak in Z (note it shows up best in data for the 3.5 degree scan. Why?)

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 34 Sources of Error - Conventional Ground Clutter

Radar Palet e Home Radar Artifacts Multi-path Echoes

Radar Palet e Home Radar Artifacts Spot the AP

Radar Palet e Home Radar Artifacts Corresponding Radial Velocity Image

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 38 AP versus Real - Compared Doppler Reflectivity

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 39 Sources of Error - Anomalous Propagation AP Strong inversions Typical early morning after clear (long) nights – fall maximum Over cold water surface – spring maximum

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 40 Anomalous Propagation of the Radar Beam AP and Real Weather Only Real Weather The Doppler Velocity View

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 41 AP and Frontal Analysis AP Anomalous Precipitation

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 42 AP … Water Vapour and Fog VISIBILITY Probably still OK

Radar Palet e Home Radar Artifacts Ground Clutter Direct reflections from ground targets, either in the main lobe or sidelobes Echoes are unusually variable in space, but constant in time (in contrast to AP, which is variable in time) Well handled by clutter filters during signal processing

Radar Palet e Home Radar Artifacts Ground Clutter Rockie Mountains persistent even on EchoTop product

Radar Palet e Home Radar Artifacts Bethune, Saskatchewan Missouri Couteau only seen on 0.5PPI Ground Clutter

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 46 Radar Beam Overshooting

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 47 PPI and CAPPI 1.5km CAPPI 4.0 km CAPPI 0.3 Degree PPI

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 48 Illustration Using King Radar NORTH Lake Simcoe Lake Ontario Lake Huron Georgian Bay

Radar Palet e Home Radar Artifacts Calculated horizon in Panorama Shaded by distance to horizon. Red is basically the neighbourhood (“look down”) and mauve is see forever. Far side of LkOntario Lake itself To Lk Huron To G.Bay Lk Simcoe North East South West North

Radar Palet e Home Radar Artifacts The Digital Elevation Map isn’t 100% complete or up-to-date. Buildings Largest Landfill in Canada Trees YOU are HERE Behind the trees

Radar Palet e Home Radar Artifacts North East South West North Blocking and Overshooting Compromise Approximate current lowest beam location BALD Approximate proposed lowest beam location LOAA

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 52 Sources of Error - Virga Typical of strong overrunning WCB with equally strong and dry CCB

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 53 Cross section to the southwest

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 54 Low-elevation angle Doppler Z PPI scan Let’s look at the same case observed by the Doppler scans Low level reflectivities to the west of the radar – rain?

Radar Palet e Home Radar Artifacts Analysis & Diagnosis Degree Doppler Z PPI scan Echoes at higher altitude precede precipitation at low Levels – virga?

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 56 Sources of Error - ECHO TOP - Beamwidth and Beamfilling

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 57 ECHO TOP Limiting by Maximum Elevation

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 58 Beam Spreading At 240 km 3 km diameter Radar beam At 30 km 0.5 km diameter Radar beam

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 59 Partial Beam Filling

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 60 ECHO TOPS - Within 36 km of the radar, echo tops will be underestimated - Within 15 km precipitation can easily go undetected - Layers of precipitation not detected: only the max tops

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 61 Radar Dome Wetting

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 62 “Clear” Air Radar Returns

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 63 “Clear” Air Radar Returns and Lake Breeze

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 64 Radar Detection of a Lake Breeze

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 65 “Clear” Air Thunderstorm Outflow Gust

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 66 Rain Rate vs Snow Rate Snow being depicted using the Rain Z-R Relationship Snow depicted using the Snow Z-R Relationship

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 67 Bird Migration and Radar

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 68 New Radar Techniques ESecond Trip processing… doubling the doppler range... out to 220 km… EBistatic Radar… multiple antennas for radiating and reception to get two components of the wind… needs GPS

Radar Palet e Home Radar Artifacts Multi-trip Echoes

Radar Palet e Home Radar Artifacts Second Trip Echoes to a distant target... first pulse returning first pulse second pulse

Radar Palet e Home Radar Artifacts Second Trip Echo actual position of echo beyond range Echo within range mapped position of 2nd trip echo Pulse One Pulse Two

Radar Palet e Home Radar Artifacts Second Trip Echo Elongated Radial Weaker Far Away Randon Doppler Changing the PRF changes Location Check the Satellite

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 73 Second Trip Processing Conventional CAPPI Doppler Reflectivity Doppler Reflectivity with Second Trip Echoes Doppler Reflectivity with Processed Second Trip Echoes

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 74 Second Trip Processing Note that the geography is wrong... Conventional Radar Cappi Doppler Radar PPI RAW 2nd Trip Echoes Doppler Radar PPI Processed for 2nd Trip Echoes

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 75 Second Trip Processing Conventional CAPPI Doppler Reflectivity Doppler Reflectivity with Second Trip Echoes Doppler Radial Velocity with Processed Second Trip Echoes

Radar Palet e Home Radar Artifacts Analysis & Diagnosis 76 Bistatic Doppler Radar Radar ARadar B GPS …. Radar A and Radar B location GPS …. Point X location Solve for the Real wind knowing the geometry and the Radar A and Radar B radial components.. Real Wind X

Radar Palet e Home Radar Artifacts Sunrise-Sunset April Sunrise