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

Contents Background Russia Radiosonde quality assessment Impact study Summary

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

Thank you for attention!