1. Extra Radiosonde Observations at 06UTC (2PM) in China Mainland and Their Impact Study on Mesoscale Model /Global Model XU Zhifang 1 CAO Yunchang 2 WANG Ruiwen 1 WANG Dan 1 GONG JianDong 1 ZHANG Lihong 1,3 TIAN Weihong 1 1 Numerical Weather Prediction Center of CMA 2 Meteorological Observation Center of CMA 3 Chengdu Institute of Plateau Meteorology of CMA SIXTH WMO WORKSHOP ON THE IMPACT OF VARIOUS OBSERVING SYSTEMS ON NWP

2. Outline Background Meso-scale model impact study –Observing System Simulation Experiments (OSSEs) –Observing System Experiments (OSEs) Global model impact study –Radiosonde impact diagnose –OSEs Discussion and conclusion

3. 2012.07.21-22 Beijing Rainfall 2012.07.25-26 Tianjing Rainfall 2012.05.13 Shaoguan Rainfall 2012.07.08 Lianyungang Rainfall 2012.08.10 Xiangshui Rainfall 2012.06.02 Shenyang Convective weather 2012.05.29 Wuhan Rainfall 2012.06.09-11 Guizhou Rainfall 2012.08.04-05 Xiangyang rainfall Hazard weather events (strong convective, heavy rainfall etc. ) generally happened in afternoon to mid-night, bring lives and property lost. Met-service demands …, more than “what’s the weather going to be ?

4. Frequency of short-duration heavy rainfall ≥ 20 mm/h (%). (Chen, 2013) SpringSummerAutumn Samples from April-September 1991-2009 Climate background of short-duration heavy rainfall

5. Diurnal variations of frequencies of Short-duration heavy rainfall ≥20 mm/h (%). 02-08BT 08-14BT 14-20BT 20-02BT Diurnal variations of average frequencies of Short-duration heavy rainfall ≥20 mm/h, and temperature of brightness blackbody on cloud top (TBB) ≤ -52 ℃. Short-duration heavy rainfall frequencies are high in the period from afternoon to evening (14BT-20BT) in summer. (Chen, 2013) Diurnal variations of heavy rainfall

6. key questions in meso-scale model How much benefit can be obtained from extra radiosondes at 14BT (Beijing time) ? How many extra stations are needed? Balance the cost & benefit Radiosonde balloon type Expensive balloon to get observations to 10hpa or cheaper one in lower and middle troposphere Could unconventional observations replace extra radiosondes? eg, GPS/PW + AMVs + others

7. Exp1: without 06UTC radiosondes Exp2 : with 06UTC 80 stations radiosondes OSSE experiments Distribution of 80 Radiosonde Stations selected by forecasters Nature run from WRF model NCEP FNL for IC & BC Resolution: 10km, 50level Domain : 55-145E, 10-70N 12 hour spin-up Simulated observations : TEMP(80), synop, ships, AMVs, GPS/PW, airep, wind-profiler Obs errors: real data obs error No obs bias be considered

8. 24h Accumulated Precipitation (Unit:mm) Nature Run (b) observation (c) Truth(WRF) (d) Truth(WRF) (a) Observation 00UTC 20 -00 UTC 21 June 00UTC 21 -00 UTC 22 June

9. Mean RMS error of 06UTC analysis (3 days average ) OSSE results

10. 00-06 06-12 12-18 18-24 Left: Equal Threat Score (ETS); Right: Bias (initial: 06UTC19, 06UTC 20, 06UTC 21, June 2014) 6hour interval accumulated simulated rainfall (init:06UTC) Precipitation threshold (mm)

11. 00-06 06-12 12-18 18-24 Left: Equal Threat Score (ETS);Right: Bias (initial: 12UTC19, 12UTC 20, 12UTC 21) 6hour interval accumulated simulated rainfall (init:12UTC)

12. Synoptic analysis Analysis of 500hpa geopotential height on 06 UTC 19 June 2014 Truth exp1 exp2

13. Truth exp1 exp2 Analysis of 700hpa wind field on 06 UTC 19June 2014 False vortex Convergence line

14. EXP1 EXP2 The 6h Accumulated Precipitation (Unit:mm) Solid line ： Truth ； Shaded ： simulated 00-06 06-12 00-06 06-12

15. Truthexp1 exp2 06UTC19 12UTC19 18UTC19 pressure longitude

16. Extra radio-sonde field experiments Period: 1-30 June of 2013, and 1-30 June of 2014 Stations: 120 stations in 2013, and 113 stations in 2014 of China Organization: China Meteorological Administration (CMA) Observing Time: 06UTC (14PM in Beijing time) (balloon released at 05:15 UTC) Observing height: 28778.3m for P/T/RH, and 27573.5m for U/V Cost : 1130 RMB per time per station (~US$200)

17. Schematic of GRAPES_RAFS configuration DATA ASSIMILATION GRAPES_RAFS （ Rapid Analysis & Forecast System ） obs data in 3h window; Basic configuration

18. OSE Experimenst Design Period:1-15 June 2014 Exp_14 : with 06UTC radiosonde (u,v,p,RH). Exp_no14: without 06UTC radiosonde. Exp_300hPa: with 06UTC radiosonde below 300hPa. Exp_nogps: with 06UTC radiosonde, without unconventional observation ( GPS/PW, AMVs, Radar VAD wind, GNSS/RO retrieval T,q ) Distribution of radiosonde stations Exp_NW: without 06UTC radiosonde at North-West area. Lower frequency for short-duration heavy rainfall Exp_NE: without 06UTC radiosonde at North-East area.

19. With & W/o 06UTC radiosonde experiment Verification: 12 UTC background VS radiosonde observation The Vertical profiles of RMSE (Red) and Bias(Blue) for background field verified against radiosonde observation at 12UTC P RH U V Solid: Exp_14 Dash: Exp_no14 Exp_14 worse Exp_14 better worse better

20. 6h rainfall verification (against 2400 AWS station) Initialization ： 06UTC Initialization ： 12UTC ETS 00-06 06-12 12-18 18-24 ETS

21. EXP_no14 Exp_14 3h (09UTC-12UTC) accumulated precipitation (Unit:mm) Solid line :observation shaded: simulated Forecast field on 12 UTC 1 June 2014; Shaded: Water vapor content at 850hPa; Solid line: geopotential height at 500hPa ; Wind barb: wind direction and speed at 850hPa Observation EXP_no14 Exp_14

22. With 06UTC radiosonde & with unconventional obs Verification: 12 UTC background VS radiosonde observation The Vertical profiles of RMSE (Red) and Bias(Blue) for background field verified against radiosonde observation at 12UTC Solid: Exp_nogps Dash: Exp_no14 P RH U V Exp_nogps worse Exp_nogps better Exp_nogps worse

23. 6h rainfall verification Initialization ： 06UTC Initialization ： 12UTC ETS 00-06 06-12 12-18 18-24

24. P U V 00-0606-12 ETS Initialization ： 06UTC Accumulated 6h simulated rainfall verification Solid: Exp_14 Dash: Exp_300hpa With 06UTC radiosonde (top to 10hpa, or 300hpa) Verification: 12 UTC background VS radiosonde observation Exp-300hpa better Exp-300hpa better

25. With & W/o 06UTC radiosonde at NW/NE of China Verification: 12 UTC background VS RS observation U U V V P P Solid: Exp_14 Dash: Exp_NW Solid: Exp_14 Dash: Exp_NE The Vertical profiles of RMSE (Red) and Bias(Blue) for background field verified against radiosonde observation at 12UTC

26. 00-06 06-12 ETS Accumulated 6h simulated rainfall verification Initialization ： 06UTC

27. ~14 stations ~81 stations ~16 stations Solar radiation bias estimate O-A (ERA) June-August, 2014, 00/06/12UTC Sippican MK2 (USA) China

28. GRAPES forecast model Non-hydrostatic equations Terrain-following coordinate Arakawa-C(horizontal) and Charney Phillips(vertical) grid 60levels, model top at 32.5km Resolution 0.5°x 0.5 °. GRAPES-3DVar Observations assimilated : conventional data (radiosondes, synops, ships, AMV and aircraft), GNSS RO, radiances(NOAA15,16,18,19,METOP-A AMSU-A) Incremental digital filter initialization GRAPES (Global/Regional Assimilation PrEdiction System) Experiment Setup Experiment 0012: Control run, with all observations Experiment 000612: Control run + 06UTCC radiosonde Experiment 0006 : 00UTC+06UTC radiosonde Cycling time: 1 st - 30 th, June, 2014 Verified against ERA-Interim and Radiosonde observation

29. Observation impact on analysis

30. 500hPa 850hPa 700hPa Observations contribution Water vapor content 6h(00-06UTC) observing precipitation

31. 850hPa 500hPa 200hPa 700hPa Observations contribution Wind

32. 850hPa 500hPa 200hPa 700hPa Observations contribution Temperature

33. GRAPES ANA-ERA in East Asia at 06UTC Temp Heigh

34. GRAPES ANA-ERA at 500hpa in East Asia at 06UTC 000612 0006 0012

35. Verificiation: GRAPES ANA-ERA in East Asia at 12 UTC

36. GRAPES ANA-ERA in East Asia at 18 UTC

37. B-O Pressure Bias and STD (against GRAPFS Ana) 06UTC 12UTC 18UTC00UTC pressure

38. GRAPES forecast in East Asia at 12 UTC

39. Verification CARD (Ref: FNL)

40. Discussion and conclusions RS data quality is the most important issues. Solar radiation bias is very likely the key reason for weakness of 6UTC radiosonde observation impact. Solar radiation bias correction scheme should rechecked for different RS type, black namelist isneeded. For troposphere, assimilating 06UTC radiosonde observations can improve forecast (eg. higher precipitation score and smaller RMSEs), especially for forecast initial from 06UTC. RS below 300hpa has similar impact for precipitation forecast. Unconventional observation data are not similar as 06UTC radiosonde observations. 06UTC RS need more research on their impact on meso-scale model and global model.

41. THANKS FOR YOUR ATTENTION!