JMA Japan Meteorological Agency QPE/QPF of JMA Application of Radar Data Masashi KUNITSUGU Head, National Typhoon Center Japan Meteorological Agency TYPHOON COMMITTEE Integrated Workshop on Urban Flood Risk Management in a Changing Climate: Sustainable and Adaptation Challenges Macao, China September 2010

JMA Japan Meteorological Agency Purpose of QPE/QPF JMA Weather Information Products of QPE/QPF High resolution data (spatial, time, intensity) Observation data

Products of QPE/QPF of JMA *Composite of echo intensity (every 30 min) *Composite of echo top height (every 30 min) * Radar/Raingauge-Analyzed Precipitation (every 30 min) *Very-Short-Range-Forecast(VSRF) of precipitation (every 30 min) （ Application ） *Analyzed 10-min precipitation (every 5 min) *Precipitation Nowcasts (every 10 min) * Soil Water Index * Runoff Index

JMA Japan Meteorological Agency Digitalized radar (automatic rejection of ground clutter) Raingauge network Communication network with rapid transmission High performance computer NWP model with high resolution NWP model with high resolution Technical base of QPE/QPF

JMA Japan Meteorological Agency Precipitation observation equipment Raingauges Radar RaingaugesRadar Advantages Can measure actual amounts of precipitation. Can observe large areas with higher spatial resolution than the raingauge network. Dis- advantages Can observe precipitation at single points only. May produce readings different from precipitation observed on the ground, as it measures the amount of rain overhead.

JMA Japan Meteorological Agency ○ Calibrate ‘radar estimate’ with raingauge data precipitation Raingauge data Radar estimate Radar/Raingauge-Analyzed Precipitation

JMA Japan Meteorological Agency Analyzed precipitation Calibration factor × ○ Calibrated ‘radar estimate’ with raingauge data are more accurate precipitation Raingauge data Radar estimate Radar/Raingauge-Analyzed Precipitation

JMA Japan Meteorological Agency JMA Japan Meteorological Agency Qualification of radar data *remove ‘false echo’ like ground clutter process Calibration over the entire radar detection range Calibration over land *modification of calibration factor Composition *using maximum value method *replace with raingauge data Radar/Raingauge-Analyzed precipitation Radar/Raingauge-Analyzed Precipitation

JMA Japan Meteorological Agency ○ Conditions in calibration （ 1 ） （ 1 ） calibration factor is a function of beam height and is calculated for each radar every time （ 2 ） （ 2 ） analyzed precipitation estimates of each radar in the area where multiple radars overlap should be equal （ 3 ） （ 3 ） analyzed precipitation estimates should be equal to the raingauge precipitation Calibration over the entire radar detection range

Calibration over the entire radar detection range (1) F1(x,y)= Fa(x,y) ｛ 1+Fx(x,y) ・ H(x,y) 2 ｝ E1(x,y)=F1(x,y)E0( x,y) calculation of Fx

Calibration over the entire radar detection range (2) calculation of Fa F1(x,y)= Fa(x,y) ｛ 1+Fx(x,y) ・ H(x,y) 2 ｝ E1(x,y)=F1(x,y)E0( x,y)

JMA Japan Meteorological Agency ① modify calibrated estimates on raingauge grids R(i) = C2(i)×E1(i) Raingauge precipitation Calibrated estimates R(i) ： raingauge precip. E1(i) ： calibrated estimates C2(i) ： factor to modify estimates raingauge grid ＊ for all the raingauge grids of the radar Calibration over land (modification)

② Determine factors of all grids over land Interpolate factors of raingauge grids to a target grid with weights. ＊ weight ＊ W 1 (i) ： for distance W 2 (i) ： for rain intensity and beam attenuation W(i)=W 1 (i)×W 2 (i) Radar precipitation ・ raingauge grids ■ factor of a target grid ＝ ∑W(i)C2(i) i : raingauge number ■ target grid Calibration over land (modification)

raingauge precipitation1-hour radar precipitation Radar/Raingauge-Analyzed Precipitation

Calibrated precipitationRadar precipitation Radar/Raingauge-Analyzed Precipitation

Composite calibrated radar data

JMA Japan Meteorological Agency JMA Japan Meteorological Agency Extrapolation of precipitation with orographic effect(EX6) process Merge EX6 and MSM(MRG) VSRF of precipitation up to 6 hours, spatial resolution 1km Flowchart of VSRF

JMA Japan Meteorological Agency Extrapolation method （ EX6 ） ･ Extrapolation method is effective up to ~ 3 forecast hours before 1 hour now after 1 hour after 1 hour 「 extrapolation 」 Move it with the same speed and the same direction as it moved. Non-linear extrapolation was introduced in 2006.

JMA Japan Meteorological Agency Outputs of Numerical Weather Prediction Data used for making VSRF *MSM(mesoscale model) operation:8 times a day *wind （ 700 ･ 900hPa ） *temperature(900hPa) *relative humidity(900hPa) *precipitation(surface) Topography data

JMA Japan Meteorological Agency JMA Japan Meteorological Agency Precipitation enhanced by orographic effect ○ Estimate precipitation due to updraft along a mountain seeder-feeder model （ Browning and Hill ， 1981 ） ･ MSM(900hPa ） temperature, wind ･ Analyzed precipitation Stationary part of precipitation over mountains caused by *cold air outbreak across the sea *low pressure Feeder cloud Pre-existing seeder cloud Moist low- level flow

JMA Japan Meteorological Agency JMA Japan Meteorological Agency Enhancement and dissipation of precipitation by orographic effect Low level wind Mountain (Pobability of the) Orographic precipitation Orographic enhancement Low level wind Movement of a echo ○ enhancement ○ dissipation

Enhancement and dissipation of precipitation by orographic effect (1) Enhancement Precipitable amount by orographic effect Without orographic effect With orographic effect Difference caused by orographic effect

Without orographic effect With orographic effect Difference caused by orographic effect Enhancement and dissipation of precipitation by orographic effect (2) Dissipation

MRG Compare the accuracy of EX6/MSM ○ using pattern distance Merging ratio considering time Merge ○ every 10 minute up to 6 hours JMA Japan Meteorological Agency Merging method Merging method Merging ratio considering space Increase the ratio of MSM as forecast time goes

Calculate the reliability “r” of MSM ○ indicate the merging ratio MRG Compare the accuracy of EX6/MSM ○ using pattern distance Calculate the merging ratio R(t) ○ using reliability r and weight function C(t) Merge ○ every 10 minute up to 6 hours JMA Japan Meteorological Agency Merging method Merging method

RA MSM EX6 Radar/raingauge precipitaion analysis at initial time （ upper left ） ・ EX6 FT=3 of the initial time 3 hours before （ lower right ） ・ latest MSM （ lower left ） calculate the reliability of MSM comparing the similarity

ratio of merge considering time ratio of EX6 at forecast time the larger the r of MSM, the smaller the ratio of EX6 red line : lower limit of the ratio of EX6 : C(t) Ratio of MSM = r ･ {1 － C(t)} reliability of MSM ＝１ reliability of MSM ＝ 0.5 FT

JMA Japan Meteorological Agency JMA Japan Meteorological Agency Examples of VSRF(Merging method) Top left R-A, top right MSM, bottom left EX6, and bottom right MRG at 11JST 31 May 2000 (6-hour forecast). MRG could predict the extending western rain systems. Same as the left figure, at 15JST 31 May 2000(6-hour forecast). MRG could predict isolated convective rain systems.

initial = 0730JST 06 June 2004 Disseminate within 3 minutes of observation time 1)Previous calibration factors (10 min before) are used. 2)Use the movement derived by VSRF 3)Only dissipation by orographic effect is introduced. 10minutes rainfall Precipitation Nowcasts 1km res.=1km, forecast every 10min Forecast 10 minute precipitation amount up to 60 minutes every 10 minute ※ with extrapolation method

JMA Japan Meteorological Agency Thank you for your attention!