1. Differential phase Experience to date on the Bolton link

2. Some definitions Differential phase is the difference in phase between the horizontally and vertically polarised components of the electric field. We are measuring the total (one-way) differential phase along the path. The Thurnham radar measures the aggregate of the two-way differential phase to, and the differential backscatter phase from, the radar volume being sensed

3. Differential Phase v Rainrate for several gamma dsds

4. Terrain for Hameldon Link

5. Cross-section along the link

6. Hameldon Hill to Clarke’s Hill Distance is 23.2km There follows a sample set of link traces and rainfall comparisons illustrating variety of data collected

7. A quiet day: 27 Oct 2005

8. Phase more stable than attenuation: 01 Mar 2006

9. Attenuation more stable than phase: 12 Mar 2006

10. Was it snow? Temp & Tip plots

11. A Dry hot day : 04 Jun 2006 Multipath?

12. The next day: not quite so hot

13. Extreme Multipath: 17 Jul 2006

14. 170706 Edgworth Wunderground Data No wind in the evening

15. And now some rain events All temperature plots come from Edgworth Wunderground website

16. Phase and attenuation similar:11 Nov 2005

17. 11 Nov 2005 Rainrate analysis I

18. 11 Nov 2005 Rainrate analysis II

19. 11 Nov 2005 Rainrate analysis III

20. A second example: 14 Sep 2006

21. Rainrates 14 Sep 2006: I

22. Rainrates 14 Sep 2006 : II

23. Not so good agreement:01 Dec 2005

24. 01Dec 2005; other data GAUGESGAUGES TEMPTEMP

25. 01 Dec 2005 : rainrate analysis

26. Possible explanation Very small drops? If the drops were almost spherical, there would still be attenuation, but no differential phase of note

27. In the next slide, look at what happens to the phase at the end of the peak at 12noon Notice also at the same moment what happens to the two attenuations The following slide shows all gauges near the link with rain around 12noon

28. 16 Jan 2006

29. GAUGESGAUGES TEMPTEMP

30. And now for some sleet events

31. 30 Dec 2005

32. 30 Dec 2005: Temp. & Gauge plots

33. 11 Apr 2006

34. 11 Apr 2006: Temp. & Tip plots

35. 11 Apr 2006: Event analysis

36. Some comments Differential phase seems to do much better than I would expect in the rain (it is not linear with rainrate) Its behaviour in sleet looks to be variable It may have identified snow It seems to be quite dependent on the atmospheric conditions