1. The Impact of the Reduced Radiosonde Observation in Russia on GRAPES Global Model Weihong Tian, Ruichun Wang, Shiwei Tao, Xiaomin Wan Numerical Prediction Center of CMA

2. Contents Background Russia Radiosonde quality assessment Impact study Summary

3. Background Russia reduced & adjusted radiosonde observation from January 2015. The impact caused by reduced data on GRAPES global model need to assess.

4. RAOB data coverage in 1 Jan 2015 RAOB data coverage in 1 Jan 2014 00UTC. 12UTC. 00UTC. 12UTC.

5. The location of reduced radiosonde coverage Blue dots for 12UTC(51) Red dots for 00UTC(28).

6. RAOB – ERAIntrim (O-A) Height Bias depend on solar angle ( Samples from Dec 2014 to Feb 2015) Vaisala RS92/Digicora III (Finland) Russia Radiosonde Region 3 in Russia Russia Radiosonde Region 2 Russia Solar angle

7. RS92/III Reduced station Height Temperature O-A (ERA) statistic: Reduced observations at 00UTC compared with Vaisala RS92/Digicora III (Finland) RS92/IIIReduced station negative bias

8. Temperature observation bias (10hpa) Vaisala RS92/Digicora III (Finland) AVK-MRZ (Russian Federation) SummerWinter Kelvin

9. RS92/III U-Wind Reduced station RS92/IIIReduced station O-A (ERA) statistic: Reduced observations at 00UTC compared with Vaisala RS92/Digicora III (Finland) V-Wind

10. Impact Study I Experiments: Use RAOB Pressure observation – GRAPES 3DVar global data assimilation system – Resolution :0.5*0.5 *62 – Observations: GTS conventional data, AMV, NOAA-15 /16/18/19 AMSUA METOP-A AMSUA – No temperature bias correction for all RAOB – Experimental Period : 1-31 January 2014 – Test 1 : use all the data (control) – Test 2 : reduced radiosonde observation

11. GRAPES Height analysis bias compare with FNL at 00UTC Reduce RAOB at 00UTC decrease the height analysis bias All data Reduce RAOB

12. GRAPES Height analysis bias compare with FNL at 12UTC Reduce RAOB at 12UTC has neutral impact on height All data Reduce RAOB

13. 00UTC u-wind analysis bias compare with FNL (700hpa) All data Reduce RAOB Reduce RAOB at 00UTC increase the wind analysis bias

14. 12UTC u-wind analysis bias compare with FNL (700hpa) All data Reduce RAOB Reduce RAOB at 12UTC has neutral impact on wind

15. GRAPES Height analysis Bias & RMSE (Unit:m) East Asia Russia （ 40-90N, 0-180E ） Russia East Asia Bias RMSE

16. GRAPES U-wind analysis RMSE (Unit:m/s) Russia East Asia （ 40-90N,0-180E ）

17. 00UTC Anomaly correlation coefficient 00/12UTC East Asia 12UTC East Asia NH

18. Impact Study II Experiments: Use RAOB Temperature observation – GRAPES 3DVar global data assimilation system – Resolution :0.5*0.5 *60 (new model version) – Observations: No AMDAR Temp obs (Temp bias), use wind observation GTS conventional data, AMV, NOAA-15 /16/18/19 AMSUA METOP-A AMSUA, GPS/RO Refractivity – No temperature bias correction for all RAOB – Experimental Period : 1-31 May 2013 – Test 1 : use all the data (control) – Test 2 : reduced radiosonde observation

19. 00UTC Height analysis bias compare with ERA (700hpa) Reduce RAOB at 00UTC has neutral impact

20. 00UTC u-wind analysis bias compare with ERA (250hpa) Reduce RAOB at 00UTC increase the wind analysis bias

21. GRAPES Height analysis Bias & RMSE (Unit:m) East Asia Russia （ 40-90N, 0-180E ） Russia East Asia Bias RMSE

22. Wind analysis error Russia （ 40-90N, 0-180E ） East Asia

23. Summary RAOBs in Russia have large negative temperature bias. bias correction is needed. The reduced RAOB in Russia has clear negative impact on wind analysis but with neutral impact on geopotential height analysis.

24. Thank you for attention!