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

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

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 m at 50m-res) Observation location 35 39’38”N ’6”E

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

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.

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

Example

Weather map surface

Weather map upper level

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

Vertical profile of T 2004/ 12/29 9JST

MRR observation Z( /29) TH cross section

MRR observation W( /29)

Bright band

Reflectivity index

Image of Snow observation

Vertical profile of MRR Wet sleetdry sleet

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

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

Limit of MRR observation TH of failure time

Picture of accumulating snow

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

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.

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

Weather map upper level /31 21JST

Surface condition 2004/12/31 Dry snow Rain

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

TH diagram of W 2004/12/31

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

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

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

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

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

Z spectrum 2004/12/31

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