1. Observation of MRR Tomoki Koshida Research fellow of OKI/KANAE lab 9/22’04 (Micro Rain Radar)

2. Today’s topic The sample of MRR observation - what we can observe? The basic of radar observation - how we can observe? The object of MRR observation - my interest

3. Schematic graph of radar 小倉義光「一般気象学」より

4. MRR observation

7. Observation sample Time height cross section of radar reflectivity

8. Observation sample2 Time height cross section of Doppler speed

9. Vertical profile(2004/4/2) Vertical axis height(m) Horizontal axis rain rate(mm/h) or speed(m/s) Black –rain rate red – Doppler speed Layer 1 Layer 2 Layer 3

10. How to analyze Radar reflectivity Doppler speed 小倉義光「一般気象学」よ り

11. Property of Radar reflectivity Radar reflectivity Z is proportional to the diameter D of raindrop to the sixth power. Radar reflectivity of Water(rain) is the larger than that of Ice(snow)

12. Summary one MRR observe radar reflectivity of rain vertically. MRR observe Doppler speed of falling rain vertically.

13. The observing parameters What is observed?

14. The number concentration

15. Rain fall rate If you want to know rain rate,

16. Summary one-prime MRR observes the back scattering cross section per unit per Doppler speed Doppler speed is converted to the diameter of rain drop : D The back scattering cross section is converted to the number concentration :N(D) Rain fall rate can be calculated above two parameters

17. MRR physical Basis Basis of Radar observation –History of Radar observation to rain –Radar equation –scattering Difference of MRR and standard radar system –Pulse radar vs. CW (continuous wave) radar –Doppler radar vs. (ordinary) radar

18. The history of radar observation Radar = radio detection and ranging To find the enemy airplane or battleship rain as noise –but if heavy rain cause strong echo then you can measure the rain fall rate

19. Radar equation(1) Transmitting power : Pt Pt/4πR 2 R

20. Radar equation(2) – antenna gain If you use antenna, you can concentrate energy : G transmitting power per unit area is Pt*G/4πR 2 R

21. Radar equation(3) – effective cross section If target area is At and effective cross section is Ae, you can receive the power : Pr R

22. Radar equation(4) – effective cross section2 From antenna theory G and Ae have following relation R

23. Radar equation(5)- back scattering cross section if energy is reflected equally(ideally), back scattering cross section is At. The energy of incidenceThe energy of reflection area At(m 2 ) The energy of reflection area σ(m 2 ) ideal area At(m 2 ) Unknown material σ(m 2 )

24. Radar equation(6) – single target Radar equation – multi target

25. Scattering cross section per volume Now introduce new parameter

26. Physical property of η Radar reflectivity for raindrop Rain drops are scattering equally in observing volume => the back scattering cross section of each drop

27. Radar equation(7) typical

28. Radar observation schematics

29. Calculate distance Pulse radar calculate distance from time

30. Pulse radar and CW radar Pulse radar CW radar (continuous wave) time Transmit power time Transmit power 2 μs4ms Receiving time tells distance

31. FMCW radar(1)

33. FMCW radar(2)

34. Stationary target

35. Moving target(1)

36. Moving target(2)

37. Summary two FMCW radar basically use the same radar equation of other radar MRR observes 29 levels of height by using frequency modulation Observing range are limited Doppler speed

38. Example of analysis My interest is to know the rain drop size distribution in the air Radar system calculate rain fall rate using Z-R relation

39. Z-R relation Z:radar reflectivity index(mm6/m3), almost the same η the radar reflectivity R:rain fall rate, the depth of rain per one hour (mm/h) B,β ： conversion parameters which differs rain by rain

40. Drop size distribution averaged over rain type Frontal : cyclone : typhoon

41. The first task Comparison between MRR and disdrometer at the ground And to know MRR character of observation about rain drop size distribution

42. Comparison between MRR and rain gauge (TE525)

43. Comparison between MRR and disdrometer(RD80)

44. Comparison between RD80 and TE525

45. Summary of accuracy comparisonTotal rain ratiocorrelation RD80 & MRR MRR/RD80 1.54 0.97 TE525 & MRR MRR/TE525 1.54 0.96 TE525 & RD80 RD80/TE525 0.99 0.97

46. Comparison of rain drop size distribution MRR and RD80 observe the rain drop size distribution We can calculate of radar reflectivity of rain drop size spectrum

47. Reflectivity of rain drops

48. Marshall & Palmer

49. Rayleigh approximation Scattering We assume the rain drop size smaller than 1/10 of wave length MRR use 12.4mm wave length Calculate the difference of Rayleigh and Mie

50. Difference between Rayleigh and Mie

51. Summary three MRR tends to overestimate Overestimate occurred at large drop size area My task is half way…..

52. Than you for your attention