2. 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

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

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

5. Radar Palet e Home Radar Artifacts Radar System Limitations

6. Radar Palet e Home Radar Artifacts Non-meteorological effects

7. Radar Palet e Home Radar Artifacts Meteorological Effects

8. 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

9. 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

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

11. Radar Palet e Home Radar Artifacts Analysis & Diagnosis 10 2 Day Precip Accum CAPPI 1.0 km Feb 16-17 2008 Nrn Ontario

12. Radar Palet e Home Radar Artifacts Analysis & Diagnosis 11 2 Day Precip Accum CAPPI 1.0 km Mar 8-9 2008 Srn Ontario

13. Radar Palet e Home Radar Artifacts Analysis & Diagnosis 12 2 Day Precip Accum CAPPI 1.0 km Mar 8-9 2008 Srn Quebec N

14. Radar Palet e Home Radar Artifacts Analysis & Diagnosis 13 2 Day Precip Accum CAPPI 1.0 km Jan 28-30 2008 Atlantic

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

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

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

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

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

20. Radar Palet e Home Radar Artifacts 60 dbZ core

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

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

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

24. Radar Palet e Home Radar Artifacts Attenuation Warm Frontal Supercell

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

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

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

28. 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?

29. 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

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

31. 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

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

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

34. 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?)

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

36. Radar Palet e Home Radar Artifacts Multi-path Echoes

37. Radar Palet e Home Radar Artifacts Spot the AP

38. Radar Palet e Home Radar Artifacts Corresponding Radial Velocity Image

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

40. 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

41. 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

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

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

44. 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

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

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

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

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

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

50. 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

51. 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

52. 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

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

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

55. 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?

56. Radar Palet e Home Radar Artifacts Analysis & Diagnosis 55 3.5 Degree Doppler Z PPI scan Echoes at higher altitude precede precipitation at low Levels – virga?

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

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

59. 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

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

61. 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

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

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

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

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

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

67. 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

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

69. 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

70. Radar Palet e Home Radar Artifacts Multi-trip Echoes

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

72. 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

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

74. 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

75. 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

76. 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

77. 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

78. Radar Palet e Home Radar Artifacts Sunrise-Sunset April Sunrise