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CLUTTER MITIGATION DECISION (CMD) SINGLE/DUAL POLARIZATION

Explore the improvements in clutter mitigation with CMD for NEXRAD enhancements, focusing on SPIN formulation refinements and dual-polarization data collection on CP2 radar.

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CLUTTER MITIGATION DECISION (CMD) SINGLE/DUAL POLARIZATION

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  1. CLUTTER MITIGATION DECISION (CMD)SINGLE/DUAL POLARIZATION Mike Dixon, Scott Ellis, John Hubbert and Greg MeymarisNational Center for Atmospheric ResearchBoulder, Colorado Technical Interchange Meeting for NEXRAD enhancementsROC, NSSL, NCAR Norman, OKNovember 2007

  2. Activities May 2007 – Nov 2007 • Preparation and delivery of AEL version 4 (draft) • Analysis of performance using modified SPIN formulation. • Modifications to SPIN membership function for new SPIN – version 4.1. • Preparation and delivery of AEL for version 4.1. • Collection of further dual-polarization data sets using SPOL. • Generalization of CMD code to run on other radars, e.g. CP2. • Installation of CMD code on CP2 in Australia, and collection of initial dual-polarization data sets from CP2. • Demonstration of CMD in clutter environment with wooded hills and ridges

  3. y x x y y x Improved SPIN formulation For a point at which a gradient sign change occurs, let x be the reflectivity change from the previous gate and y be the reflectivity change to the next gate. Then SPIN CHANGE = (|x| + |y|) / 2 Tests with this new formulation show (minor) improvements over theprevious version.

  4. Change in SPIN membership function fornew formulation -> (30,1) -> (15,0)

  5. Dual pol data collection on CP2 • CP2: previously owned by NCAR, now operated by the Australian Bureau of Meteorology • S-Band, 1 MW, fast-alternating mode dual polarization transmission, single receiver (co-polar) • Ferrite switch for the H/V alternating mode: 25 dB isolation • X-Band, 200KW, transmit H, receive H and V, non-Doppler • Site: on top of a small hill, Redbank Plains, 30 km SW of Brisbane, Queensland, Australia • Topography: wooded hills and ridges, valleys

  6. CP2 antenna: S and X band

  7. CP2 site, Redbank Plains, Australia

  8. CP2 site, Redbank plains

  9. Brisbane region, CP2 site shown 40 km

  10. CP2 dual pol case 2007/11/16 – DBZ unfiltered

  11. CP2 dual pol case 2007/11/16 – DBZ filtered

  12. CP2 dual pol case 2007/11/16 – VEL unfiltered

  13. CP2 dual pol case 2007/11/16 – TDBZ

  14. CP2 dual pol case 2007/11/16 – SPIN

  15. CP2 dual pol case 2007/11/16 – CPA

  16. CP2 dual pol case 2007/11/16 – ZDR SDEV

  17. CP2 dual pol case 2007/11/16 – DBZ unfiltered

  18. CP2 dual pol case 2007/11/16 – CMD

  19. CP2 dual pol case 2007/11/16 – CMD flag

  20. CP2 dual pol case 2007/11/16 – DBZ unfiltered

  21. CP2 dual pol case 2007/11/16 – DBZ filtered

  22. CP2 dual pol case 2007/11/16 – clutter

  23. CP2 dual pol case 2007/11/16 – VEL filtered

  24. Wooded ridges to West of CP2 site 10 km

  25. CP2 ridge – DBZ unfiltered Weather

  26. CP2 ridge – TDBZ Weather

  27. CP2 ridge – SPIN Weather

  28. CP2 ridge – CPA Weather

  29. CP2 ridge – ZDR SDEV Weather

  30. CP2 ridge – DBZ unfiltered Weather

  31. CP2 ridge – CMD Weather

  32. CP2 ridge – CMD flag Weather

  33. CP2 ridge – DBZ unfiltered Weather

  34. CP2 ridge – DBZ filtered Weather Filtered, but some clutter leaks through

  35. CP2 ridge – clutter Weather

  36. CP2 ridge – vertical section Weather

  37. CP2 vert section – DVZ unfiltered Weather

  38. CP2 vert section – TDBZ Weather

  39. CP2 vert section – SPIN Weather

  40. CP2 vert section – CPA Weather

  41. CP2 vert section – ZDR SDEV Weather

  42. CP2 vert section – PHIDP SDEV Weather

  43. CP2 vert section – CMD Weather

  44. CP2 vert section – CMD FLAG Side-lobes Weather

  45. CP2 vert section – DVZ unfiltered Weather

  46. CP2 vert section – DVZ filtered Weather

  47. CP2 vert section – Clutter Weather

  48. Conclusions • The SPIN CHANGE formulation was updated tomake it symmetrical with respect range. • The SPIN membership function was updated to suit the new formulation. • The AEL for CMD version 4.1, which includes this new formulation, was delivered to the ROC. • CMD was successfully ported to run on other radars, e.g. CP2. • CP2 is located in a challenging clutter environment, sitting on top of a hill with a good view of hills and ridges covered with trees. • A CP2 data set was collected, and CMD was run on this data set. • Initial results indicate that CMD performs well in this environment. • A more extensive data set is required.

  49. THANK YOU

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