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Day 2: WSR-88D Data Quality and Impacts on Interpretation

Day 2: WSR-88D Data Quality and Impacts on Interpretation. Paul Schlatter (CIMMS/WDTB) Jami Boettcher (WDTB) Metr 4803 April 14, 2005. Overview. Data Quality Product characteristics Operator intervention Non-Meteorological Returns Data Quality and the NWS Warning Process.

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Day 2: WSR-88D Data Quality and Impacts on Interpretation

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  1. Day 2: WSR-88D Data Quality and Impacts on Interpretation Paul Schlatter (CIMMS/WDTB) Jami Boettcher (WDTB) Metr 4803 April 14, 2005

  2. Overview • Data Quality • Product characteristics • Operator intervention • Non-Meteorological Returns • Data Quality and the NWS Warning Process

  3. Where’s the Weather?

  4. WSR-88D Data Quality • Ground Clutter and Anomalous Propagation • Range Folding • Velocity Folding => Improperly Dealiased Velocities

  5. Ground Clutter(Normal) • Reflectivity: high power, lacking smooth gradients

  6. Ground Clutter(Normal) • Velocity: generally near zero

  7. Anomalous Propagation (AP) • Transient form of clutter contamination • Beam is refracting more than standard • Nocturnal cooling in valleys • Behind cold fronts, dry lines

  8. Anomalous Propagation(Transient) • Reflectivity: high power, lacking smooth gradients, radially oriented

  9. Anomalous Propagation(Transient) • Velocity: generally near zero

  10. Anomalous Propagation(Transient) • Spectrum Width: generally low

  11. Clutter SuppressionOperator Defined

  12. Clutter SuppressionOperator Defined • Geographic regions defined • Type of suppression • Bypass Map for normal clutter • All Bins for transient clutter (AP) • Level of suppression

  13. AP Removal ExampleReflectivity

  14. AP Removal ExampleVelocity

  15. AP Removal ExampleReflectivity

  16. AP Removal ExampleVelocity

  17. Data Quality Improvement

  18. Data Quality Improvement

  19. AP and Normal Clutter RemovalReflectivity • No suppression applied

  20. AP and Normal Clutter RemovalVelocity • No suppressionapplied

  21. AP and Normal Clutter RemovalReflectivity • Normal clutter suppression applied

  22. AP and Normal Clutter RemovalVelocity • Normal clutter suppression applied

  23. AP and Normal Clutter RemovalReflectivity • AP and Normal clutter suppression applied

  24. AP and Normal Clutter RemovalVelocity • AP and Normal clutter suppression applied

  25. Data Quality Improvement

  26. Data Quality Improvement

  27. Inappropriate Suppression Applied • All Bins, High suppression in Batch tilts

  28. Inappropriate Suppression Applied • All Bins, High suppression in Batch tilts

  29. Inappropriate Suppression Applied • All Bins, High suppression in Batch tilts

  30. Inappropriate Suppression Corrected • Bypass Map suppression in Batch tilts

  31. Range Folding • Result of multiple trip echoes • For velocity data, high PRFs needed to minimize velocity folding • Doppler Dilemma: high PRFs mean short Rmax • Purple typically used to denote velocity data unavailable due to range folding

  32. Range Folding

  33. Range FoldingWarning Forecaster’s Nightmare

  34. Range FoldingWarning Forecaster’s Nightmare

  35. Range FoldingOperator Intervention • Doppler PRFs can be manually selected • Will shift Rmaxanddistribution of purple

  36. PRF Selection BWER

  37. PRF Selection PRF #8 Rmax ~ 63 nm

  38. PRF Selection PRF #4 Rmax ~ 95 nm

  39. Velocity Folding • WSR-88D uses a Velocity Dealiasing Algorithm • Sometimes velocities are improperly dealiased

  40. Improperly Dealiased Velocities • Most likely on “leading” edge of storms

  41. Improperly Dealiased Velocities • Most likely on “leading” edge of storms

  42. Improperly Dealiased Velocities • Next higher elevation

  43. Improperly Dealiased Velocities • Next volume scan

  44. Improperly Dealiased VelocitiesOperator Intervention • Environmental Winds Table

  45. Non-Meteorological Returns • Chaff • Dust Storm • Sunspikes • Interference • Biological Targets

  46. Chaff • Lightweight, highly reflective targets

  47. Dust Storm • West Texas: 2 fatalities

  48. Sunspikes • Sun is CW emitter • Contiguous returns along radials at sunrise and sunset

  49. Interference • Internet transmitter at Huntington Beach

  50. Interference • Privately owned ATC radar 2 mi from ILN

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