1. Dual-polarimetric and multi-Doppler analysis of a High Plains supercell Darren Clabo Nick Guy Nathan Hitchens

2. Outline Introduction Background Dual-polarimetric Doppler analysis Multi-Doppler analysis Summary

3. Introduction

6. Soundings DNR LBF RIW

9. Surface Observations

10. Storm Information Initiation: 2337 UTC on 4 June 2009 –First reflectivity seen aloft (8.81 km) at 2326 UTC on 4 June 2009 Last radar scan by CSU-CHILL at 0112 UTC on 5 June 2009

11. 1km Visible Satellite Storm initiation

12. CSU-CHILL Reflectivity

14. CoCoRaHS Reports

15. SHAVE Reports

16. Background

17. Supercell Model Klemp (1987)

18. Polarimetric Radar Signatures in Supercell Thunderstorms Kumjian and Ryzhkov (2008)

19. Polarimetric Radar Signatures in Supercell Thunderstorms Z DR arc signature –Usually found on the right southern edge of the forward flank downdraft –Shallow (1-2 km in depth) –Effect of size sorting of raindrops resulting from vertical increase in speed and veering of storm-relative winds Kumjian and Ryzhkov (2008)

20. Polarimetric Radar Signatures in Supercell Thunderstorms Hail signature –Low Z DR value (near 0) due to chaotic orientation of tumbling hailstones Kumjian and Ryzhkov (2008)

21. Polarimetric Radar Signatures in Supercell Thunderstorms Inflow signature –Vigorous low-level inflow into supercells may contain nonmeteorological scatterers (e.g. grass, leaves, dust) –Results in lower values of ρ HV Kumjian and Ryzhkov (2008)

22. Polarimetric Radar Signatures in Supercell Thunderstorms Updraft signature –Light debris may be ingested into updraft from inflow and a lack of hydrometeors may exist –Results in low ρ HV aloft

23. Polarimetric Radar Signatures in Supercell Thunderstorms Z DR columns –High values associated with updrafts indicative of large raindrops or water-coated hailstones –Narrow (4-8 km wide) –Increasing values associated with updraft intensification, and thus storm intensification Kumjian and Ryzhkov (2008)

24. Radar Coverage Dual-polarized, S-band –CSU-CHILL Single-polarized, S-band –CSU-PAWNEE –Denver NEXRAD (KFTG) –Cheyenne NEXRAD (KCYS)

25. Vorticity calculated using the tangential shear between two points corresponding to the maximum inbound and outbound velocities not more than 10 km apart in an area thought to contain the updraft –Updraft denoted by bounded weak echo region aloft Red line denotes minimum vertical vorticity for a mesocyclone as described by the synthesis of Bunkers et al. (2009) Storm undergoing new updraft growth

26. Dual-Polarimetric Doppler Analysis

27. 2352 UTC - Base

28. 2352 UTC – Sweep 4

29. 0013 UTC - Base

30. 0013 UTC – Sweep 4

31. 0020 UTC - Base

32. 0020 UTC – Sweep 4

33. 0046 UTC – Sweep 4

34. 0049 UTC - Base

35. 0049 UTC – Left Split

36. 0053 UTC - Base

37. 0053 UTC – Sweep 4

38. 0106 UTC - Base

39. 0106 UTC – Sweep 4

40. 0109 UTC – Base Updraft

41. 0109 UTC – Sweep 4 Updraft

42. Multi-Doppler Analysis

43. Multi-Doppler Analyses Radar data edited in SOLOII –Removal of egregious data Interpolated to Cartesian grid via REORDER software package Dual- and Multi-Doppler analyses performed with CEDRIC software package –Extremely finicky!

44. Radar Ranges

45. Multi-Doppler Analyses Quad Dual Triple

46. Vertical Wind Calculation Downward integration Upward integration Variable Integration

47. Continuity 090605_0106Z 090605_0109Z

48. Vertical Structure 1.50 km 3.0 km

49. Vertical Structure 4.50 km 6.5 km

50. Vertical Structure 8.0 km 10.0 km

51. Vertical Wind / ρ HV relationship ρHV ZDR

52. Summary

53. Dual-Polarimetric Analysis Storm consisted of three distinct right-moving updrafts, though possibly more –Cyclonic rotation –New cells formed on flanking line Two distinct left moving updrafts –Anticyclonic Storm exhibited supercellular characteristics through most of its lifetime –Persistence and depth of significant (> 0.3 x 10 -2 s -1 ) vertical vorticity Exhibited: –Cyclic updrafts –Velocity couplets aloft and at lowest scan elevations –Storm splitting Right and left movers Shedding updrafts –Z dr arcs –Lowering of ρ hv in mesocyclone center

54. Multi-Doppler Analysis Continuity with previous scan time suggests results are robust for instantaneous analysis Tri-Doppler analysis produces “best” results due to beam propagation characteristics and over-determined solutions Variable integration technique produced best results Vertical structure shows –Poor agreement at extreme lower upper and levels –Reasonable results when compared to radar analysis Unclear whether ρ HV is possibly correlated to calculated vertical wind

55. Acknowledgements Special thanks to our mentors: –Wen Chau Lee –Pat Kennedy –Tammy Weckwerth Also thanks to…. –NCAR, ASP, and the colloquium organizers –Mike Bell –Tracy Emerson –Group 10b

56. “This is indicative of a deep psychological problem.” – Pat Kennedy

57. 0011 UTC – TBSS

58. 0011 UTC – TBSS2

59. 0008 UTC – Sweep 5

60. 0017 UTC - TBSS

61. 0037 UTC - TBSS

62. 0031 UTC – Sweep 2

63. Velocity Fields