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Adaptive Estimation and Tuning of Satellite Observation Error in Assimilation Cycle with GRAPES

Adaptive Estimation and Tuning of Satellite Observation Error in Assimilation Cycle with GRAPES. Hua ZHANG, Dehui CHEN, Xueshun SHEN, Jishan XUE, Wei HAN China Meteorological Administration (CMA). OUTLINE. Introduction of GRAPES-3DVar Tuning of obervation error in data assimilation

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Adaptive Estimation and Tuning of Satellite Observation Error in Assimilation Cycle with GRAPES

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  1. Adaptive Estimation and Tuning of Satellite Observation Error in Assimilation Cycle with GRAPES Hua ZHANG, Dehui CHEN, Xueshun SHEN, Jishan XUE, Wei HAN China Meteorological Administration (CMA)

  2. OUTLINE • Introduction of GRAPES-3DVar • Tuning of obervation error in data assimilation • Latest development in the global assimilation/prediction experiment：2008 • Summary

  3. 1. Introduction of GRAPES-3DVarMain features of GRAPES_GAS

  4. GRAPES_GFS Raw ATOVS DATA analysis：1.875 ° forecast：1 ° Preprocessing GRAPES GLOBAL 3D-VAR Quality Control cycle INCREMENTAL SI DIGITAL FILTER INITIALIZATION Conventional DATA Preprocessing GRAPES GLOBAL MODEL 10D Forecast At 00/12Z Quality Control 6h Forecast

  5. 2. Tuning of background and observation error in data assimilation (Wei HAN and Jishan XUE,2007) • Cost function Bacground error: Observation error: • Basic hypothesis: ?? ?? • Optimality criterion (Bennet 1992;Talagrand,1999)

  6. innovation covariance: Desrosies et al.,2005 (1) Iterative fixed-point method: (2)

  7. only Sonde RH observation assimilation in GRAPES regional 3DVAR 20070601-0614 Only RH obs. are assimilated to test the approach, since it is thus a univariate analysis Blue dot: initial obs. error of rh Blue dash dot: initial background error of rh

  8. NOAA16,AMSUA20070601-0614 diagnosis Obs erro Bak. erro

  9. ITWG NWP WG list of assumed observation errors

  10. Against Radiosonde：humididy information of AMSUB has a proper response in GRAPES-3DVAR 59948,Sanya 58238,Nanjing Red : xb Blue : xa(amsub) Black : Sounde

  11. Independent verification: RH[xa(amsub)]-Y(sonde) Before Tuning After Tuning Black:Before Tuning; Red:After tuning 10 cases statistics 2007060900,500hPa

  12. Tuning of observation error improve GRAPES(30km) QPF

  13. 3.Latest development in the global assimilation/prediction experiment：2008 (Xueshun SHEN et al,2008) • Re-estimate the obs. error of sonde and radiances • SEMI-Bias Correction in background • Modify the QC of satellite radiances • Introduce NOAA-15 • Improve the surface albedo • Introduce the diagnostic cloud ref. ECMWF • Introduce the new O3 data • Daily SST

  14. Data application of GRAPES-3DVAR • ATOVS microwave (NOAA15 16 17) radiances • Sondes geop/ humidity / wind • Synops geop/ humidity/ wind • Ships geop/ humidity/ wind • Airep temp/ wind • Satob wind

  15. 500hPa ACC against NCEP • 考虑模式偏差的卫星资料偏差订正 • 模式偏差订正参数调整(0.9,0.3) • 背景误差(循环同化预报结果统计) • 探空资料质量控制 • 卫星资料背景场误差和观测误差的估计 • 卫星资料质量控制新方案(Background Check) • 海温资料更新 • 湿度分析（水物质相态） • 采用增量插值标准初始化方案 • 针对南极探空的质量控制 冬春夏秋 走过四季

  16. 北半球，10天预报的500hPa ACC检验(.vs. NCEP ANA.)(2006120112－2007013112, 62cases)

  17. 南半球，10天预报的500hPa ACC检验(.vs. NCEP ANA.)(2006120112－2007013112, 62cases)

  18. 南半球预报检验，31cases(200612), against NCEP ANA. NOAA-15资料的影响试验

  19. Summary • It is promising for the new implementation of the tuning observation error. • GRAPES is progressing ,which improve its performance. • Sondes are important in southern pole region. • more satellite data application

  20. Thanks!

  21. Suggestions? • Assimilation: more satellite data application, especially in SH and ocean  any possible data (real-time) & experiences? • Model • Weak subtropical high • Excessive precipitation over the maritime continent • Large cooling bias at top (~10hPa) • Coupling of SISL dynamics & physics • Hybrid vertical coordinate in non-hydrostatic model

  22. 考虑了背景偏差的卫星资料观测偏差订正方案：“半偏订正”考虑了背景偏差的卫星资料观测偏差订正方案：“半偏订正” It is obvious that the systematic departure : H(xb)-Yo , Is due to model bias, So we make a “Semi-Bias” correction As a regularization term in VarBC

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