1. The Tokyo First snow observed by MRR Tomoki Koshida Research fellow of OKI/KANAE lab 1/11’05

2. Today’s topics What defines a hydrometer? Synoptic condition Surface condition Observation results Discussion

3. Specification of MRR Transmit frequency24.1GHz Transmit power50mW Receive-transmitter antennaOffset parabolic,0.6m diameter Beam width2degree(35m at 1km) ModulationFMCW Height resolution10 – 200m Averaging time10 – 3600s Height range29range gate (e.g..50-1500m at 50m-res) Observation location 35 39’38”N 139 41’6”E

4. Snow falling scene 2004/12/29 rain => snow 2004/12/31 snow => rain

5. What defines a hydrometer? *hydrometer is a particle of water in the air. For example, cloud particle, rain, snow, hail and so on. Ice melts to water at the degree of 0.

6. Example of threshold snowflake Rain snow diagram sleet rain Relative humidity Temperature02-3

7. Example

8. Weather map surface

9. Weather map upper level

10. Surface condition Time series of T and RH Wet sleet period Dry sleet period

11. Vertical profile of T 2004/ 12/29 9JST

12. MRR observation Z(2004 12/29) TH cross section

13. MRR observation W(2004 12/29)

14. Bright band

15. Reflectivity index

16. Image of Snow observation

17. Vertical profile of MRR Wet sleetdry sleet

18. Doppler spectrum 2004/12/29 wet Spectrum graph Formation ice phase Accrete phase Shrink phase

19. Doppler spectrum 2004/12/29 dry Formation ice phase melting phase Shrink phase

20. Limit of MRR observation TH of failure time

21. Picture of accumulating snow

22. Micro wave absorption A Chinese bean-jam bun will be hotter in contents than shells.

23. Conclusion 1 MRR observed snow & melting snow The result is consistent in previous study And more, precise structure of bright band given Too much snow and melting water prevents us from snow observation.

24. Weather map surface 2004/ 12/31 15JST Synoptic situation

25. Weather map upper level 2004 12/31 21JST

26. Surface condition 2004/12/31 Dry snow Rain

27. TH diagram of Z 2004/12/31 TH Vertical profile Z spectrum Speculation

28. TH diagram of W 2004/12/31

29. Vertical profile of Z,W 2004/12/31 snow rain

30. Vertical profile of T 2004/ 12/31 15JST GPV initial

31. Vertical profile of T,RH 2004/ 12/31 15JST GPV initial 0%50%

32. Doppler spectrum 2004/12/31 snow snow Formation ice phase Shrink ice phase

33. Doppler spectrum 2004/12/31 rain rain Formation ice phase Melting ice Shrink but growth Rain

34. Z spectrum 2004/12/31

35. conclusion MRR observed Doppler spectrum The spectrum will consist in qualitative analysis MRR could investigate precipitation system