1. Satellite Bias Correction for CFSRR Haixia Liu, Russ Treadon, Robert Kistler, John Derber, Suru Saha and Hua-lu Pan Nov. 7, 2007 with input from Jack Woollen, Quanhua Liu, Moorthi Shrinivas, Cathy Thiaw and others

2. radiance used radiance NOT used …… (Reference)

3. What’s needed to assimilate radiance? CRTM model, CRTM coeff files satinfo which contains the usage flag, obs error and Instrument/observation characteristics (microwave/IR, etc.) Radiance obs bias correction is needed.

4. Why bias correction (BC)? RTM are subject to systematic errors. Radiance obs contain systematic errors. Magnitudes of these errors are comparable with radiance changes corresponding to typical errors in the T from short-range forecast model. Try to use radiance to improve the accuracy of the T field during DA process.

5. Satellite Bias Correction in GSI Observation bias Scan bias (slowly evolve) Air mass bias (dependent on atmospheric state) is the coefficients of predictors Constant Zenith angle Cloud liquid water Square of T lapse rate T lapse rate etc.

6. Adaptive BC in GSI Allow temporal variation of the coefficients using data assimilation Variational bias correction Find the optimal  to minimize the cost function J through the variational procedure. VS

7. 2 BC files are required to run gsi 1)Coefficients for predictor part of BC (biascr.gdas.*) Updated within inner loop of analysis 2)Slowly evolving angle dependent part of BC (satang.gdas.*) Updated in separate job step following analysis using T b innovation file Method: Start from guess values and run a training period. Experiments were conducted to see if this procedure can lead to convergence to the operational values (‘truth’) after the training period.

8. AMSU Blue: EXP Red: CNTL Preliminary Results

9. Blue: EXP Red: CNTL HIRS

10. Scan bias and air mass mean bias compensate to each other. Combine the scan bias and mean term together to avoid the compensation between them. Remove predictor zenith angle.

11. The coefficients for predictor cloud liquid water should not start from 0 since this term evolves very slowly. Only applied to amsua data available after 199810. Will start from average value used in operation.

12. GSI codes and scripts ready for CFSRR Modify GSI code and analysis script to handle pre- NOAA-14 satellites/sensors. Modification made in GSI and link to new CRTM which considers co2 leaking in cell pressure modulator which ssu data suffers. GSI is basically frozen for CFSRR now.

13. Generating satinfo historical files The satinfo historical files are generated every 6 hours from 1979 to present. The satellite/sensor/channel use flag is turned on/off in satinfo files based on the GMAO blacklist and data availability at NCEP. Amsua_aqua channel 4 is going to be used as QC purpose rather than assimilated. Amsua_n16 chn4 is in monitor mode. Questions: hirs2_n11 in 2 nd period is extended to 20000426 and ssu_n11 is extended to 20040616 (GMAO ends using them at Feb 1999 and ERA40 ends using them in Sep 1998); ssu-n12 data is going to be used extending from 19970530 to the end of 1998.

14. Bias correction exp list For sensors/satellites before NOAA 15, the bias correction spin up must be done ahead of CFSRR production. combine all the spun up BC for all channels/sensors/satellites together to formulate a huge biascr.gdas.* and satang.gdas.* file which will be used in CFSRR production.

15. satellitesensorStart dateEnd date tirosnHirs21979010119800121 Msu1979010119790626 ssu19790101 19800129 19800121 19810205 N06Hirs21979071319830418 Msu19790701 19851015 19830418 19861118 ssuSame as msu N07Hirs21981082419850205 Msu1981080119850219 ssuSame as msu N08Hirs21983050119840621 MsuSame as hirs2 ssu N09Hirs21985022519881102 Msu1985022519870308 ssu1985022519881102 N10Hirs21986112619910902 msuSame as hirs2 N11Hirs21988110819941231 MsuSame as hirs2 ssu

16. N11 2 nd period Hirs21997071519990226 MsuSame as hirs2 ssu N12Hirs21991091619911225 1992030819930610 1993061919970530 Msu1991091619970524 N14Hirs21995050120060925 MsuSame as hirs2 ssu1995011920060505 N15Hirs319981026 [hl1] [hl1] 20000607 amsua1998102621001231 amsubSame as amsua N16Hirs3200101 [hl2] 26 [hl2]20040521 amsua2001012420021121 2002112821001231 amsub2001012421001231 N17Hirs32002071521001231 amsua20020715 [hl3] [hl3] 20031028 amsubSame as hirs3 [hl1] Hirs3_n15 are not used any more by GDAS in operation.[hl1] [hl2] Hirs3_n16 are not used any more by GDAS in operation.[hl2] [hl3] Amsua_n17 are not used any more by GDAS in operation.[hl3]

17. N18Hirs4Not use amsua2005110121001231 mhsSame as amsua Metop-aHirs42007052121001231 amsuaSame as hirs4 mhs aquaairs2002101221001231 amsuaSame as hirs4 G08sndr1994041320030401 G10sndr1997042520060621 G11sndr20060621 [hl1] [hl1] 20070529 sndrD12007052921001231 sndrD2 sndrD3 sndrD4 G12sndr2003040120070529 sndrD12007052921001231 sndrD2 sndrD3 sndrD4 [hl1] Sndr_g11 are not used any more by GDAS in operation.[hl1]

18. 4 Simultaneous Streams Jan 1979 – Sep 19868 years Apr 1986– Oct 19937 1/2 years Apr 1993 – Oct 20007 1/2 years Apr 2000 – Feb 201010 years 6 month overlap for ocean and land spin ups Total of 33 years of Reanalysis

19. The first priority (the beginning of the 4 streams): 1979010100 1986040100 1993040100 2000040100 The 2nd priority (closest to the beginning of the 4 streams): 1979070100 1986112500 The bias correction must be done first for the beginning of these 4 streams. Thus we have 4 more exps to spin up BC. The 3rd priority (2nd closest to the beginning of the 4 streams): 1981080100 1988110800 1994041300(goes08) 1995011900 1995050100 2001012400(n16) 2002071500(n17)...... The first 4 spin up exps start from the beginning of each stream. Subsequently, we consider to spin up BC for other sensors/satellites according to their usage timing.

20. Future work 21 satellite bias correction spin up experiments should be done by the end of 2007. Sensitivity of bias to the atmospheric IC. Start from r2 or gdas of the previous cycle? Tests on amsua_n15 indicate that the bias correction is not very sensitive to the IC (the current predictors chosen can identify obs bias from NWP model error.) Possible issues related to SSU bias correction and assimilation.