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Dual Polarization Technology: Coming Soon To a Radar Near You

Dual Polarization Technology: Coming Soon To a Radar Near You. Paul Schlatter Warning Decision Training Branch. Outline. Overview Base and Derived Products What to expect Training During Upgrade. WSR-88D with Dual-Pol. Transmitted at 45 o Polarization.

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Dual Polarization Technology: Coming Soon To a Radar Near You

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  1. Dual Polarization Technology:Coming Soon To a Radar Near You Paul Schlatter Warning Decision Training Branch

  2. Outline • Overview • Base and Derived Products • What to expect • Training • During Upgrade

  3. WSR-88D with Dual-Pol • Transmitted at 45o Polarization

  4. Compare to Current WSR-88D (NEXRAD) Policy of “Do no harm” Retrofit on existing dish, tower, etc. Same scanning strategies Same data resolution Velocity, SW, Reflectivity, Algorithms: Unchanged

  5. List of New Products via Dual-Pol • Differential Reflectivity (ZDR) • Correlation Coefficient (CC) • Specific Differential Phase (KDP) • Algorithms • Melting Layer • Hydrometeor Classification • 9 NEW Precipitation Estimation Products

  6. The Dual-Pol Base Products

  7. Differential Reflectivity (ZDR)

  8. Physical Interpretation Zv Zv Zv Zh Zh Zh Zh ~ Zv Zh > Zv Zh < Zv

  9. KOUN 0.5 deg Z

  10. KOUN 0.5 deg ZDR

  11. KOUN 0.5 deg Z

  12. KOUN 0.5 deg ZDR

  13. Correlation Coefficient (CC) N

  14. Physical Interpretation

  15. KOUN 0.5 deg Z

  16. KOUN 0.5 deg CC

  17. Differential Phase Shift (ΦDP “PhiDP”) • Horizontal and vertical pulses slow down through medium • Causes phase shifts in both pulses • Phase shifts are different depending on target shape and concentration • Immune to partial beam blockage, attenuation, hail • Difference in phase shifts = ΦDP

  18. Physical Interpretation • Similar to ZDR • Particle Concentration FDP = 0 FDP = Decreases FDP = Increases FDP = 10o FDP = 25o

  19. Differential Phase Shift (ΦDP)

  20. KDP is what you will be interpreting (unless you have GR analyst and love loads of pretty colors) From PhiDP to KDP Gradients Most Important

  21. Specific Differential Phase (KDP)

  22. Running Review of the DP Products ZDR: Indicator of hail and median rain drop size CC: Distinguish precip vs. non precip and homogeneous vs widely varying precip type KDP: Identify heavy rain; immune to blockage and hail

  23. Base Data Summary • Need to integrate at a minimum Z, ZDR, and CC to analyze the situation to determine precip type • AWIPS is ready • How realistic is that during the crunch of a warning decision? • Richard Dreyfuss as Dr. Leo Marvin

  24. Dual-Pol Algorithms

  25. 1. Melting Layer Detection Algorithm 4.3o CC • Melting hydrometeors easy to detect • CC decreases to ~0.90

  26. 2. Hydrometeor Classification Algorithm • Algorithm makes best guess of dominant radar echo type • For every radar elevation angle Lgt/mod rain Heavy rain Hail “Big drops” Graupel Ice crystals Dry snow Wet snow Unknown AP or Clutter Biological Current Classification Options

  27. KOUN 0.5 deg Z6.6 kft MSL in hail KOUN 0.5 Deg Z 1.5” hail reports

  28. KOUN 0.5 deg HC6.6 kft MSL in hail KOUN 0.5 Deg Z AP Tagged Fairly Well 1.5” hail reports

  29. 3. Dual-Pol QPE • Research in C. Oklahoma has shown DP QPE superior to traditional Z(R), reducing error by 50% within ~80 nm

  30. Dual-Pol Training Plans

  31. When/What is the Impact? • All WSR-88Ds upgraded 2010-2012 • 10-14 days radar downtime during upgrade

  32. Target Two Critical Stakeholders

  33. Current Dual-Pol Schedule

  34. Questions? Paul.T.Schlatter@noaa.gov www.wdtb.noaa.gov/modules/dualpol

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