the impact of the reduced radiosonde observation in russia on grapes global model weihong tian,...
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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 2015.• 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 2014
00UTC. 12UTC.
00UTC. 12UTC.
The location of reduced radiosonde coverage
Blue dots for 12UTC(51) Red dots for 00UTC(28).
RS92/III Reduced stationHeight
Temperature
O-A (ERA) statistic: Reduced observations at 00UTC compared with Vaisala RS92/Digicora III (Finland)
RS92/III Reduced station
negative bias
Temperature observation bias (10hpa)
Vaisala RS92/Digicora III (Finland) AVK-MRZ (Russian Federation)
Summer Winter
Kelvin
RS92/III
U-Wind
Reduced station
RS92/III Reduced 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
00UTCu-wind analysis bias compare with FNL (700hpa)
All data
Reduce RAOB
Reduce RAOB at 00UTC increase the wind analysis bias
12UTCu-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 AsiaRussia
( 40-90N, 0-180E)
Russia
East Asia
BiasBias
RMSE 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
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
00UTCHeight analysis bias compare with ERA (700hpa)
Reduce RAOB at 00UTC has neutral impact
00UTCu-wind analysis bias compare with ERA (250hpa)
Reduce RAOB at 00UTC increase the wind analysis bias
GRAPES Height analysis Bias & RMSE (Unit:m)
East AsiaRussia
( 40-90N, 0-180E)
Russia
East Asia
BiasBias
RMSE 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!
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