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STAR CrIS SDR CalVal Task Performance

STAR CrIS SDR CalVal Task Performance. Yong Han, Denis Tremblay, Xin Jin, Likun Wang and Yong Chen October 23-24, 2012, CrIS Review Meeting Provisional Maturity Level. Tasks Performed at STAR. Task 2 Web-based Trending and Monitoring System.

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STAR CrIS SDR CalVal Task Performance

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  1. STAR CrIS SDR CalVal Task Performance Yong Han, Denis Tremblay, Xin Jin, Likun Wang and Yong Chen October 23-24, 2012, CrIS Review Meeting Provisional Maturity Level

  2. Tasks Performed at STAR

  3. Task 2 Web-based Trending and Monitoring System Spacecraft reset into Earth point safe mode on June 21; the measured laser wavelength slowly moved back to normal after June 25. Measured laser wavelength shows downward trend since 09/2012 ; the CMO will be re-calculate when wavelength drift exceeds the threshold. The upload of EngPkt v34 on June 27 fixed the pixel-level quality flag bug: the percentage of degraded pixels decrease to nearly zero. More than 60 parameters are automatically monitored: http://www.star.nesdis.noaa.gov/smcd/spb/xjin

  4. Task 3: Inter-Sensor Comparison CrISvs. IASI at SNOs IASI CrIS Total of 852 SNO Pairs 411 North Pole 441 South Pole CrIS - IASI CrIS and IASI have an agreement of 0.2K or better for all 3 bands.

  5. Task 3: Inter-Sensor Comparison CrISvs. AIRS at SNOs CrIS AIRS CrIS - AIRS CrIS and AIRS have an agreement of 0.3K or better over SNO locations at North Pole for 1253 pairs.

  6. Task 3: Inter-Sensor Comparison CrISvs. VIIRS NEdT large at low temperature CrIS-VIIRS CrIS-VIIRS Scene-temperature dependence can be seen at Band M15 CrIS is warmer than VIIRS at M15 and M16 but is colder at M13 CrIS-VIIRS BT difference for SNO cases are consistent with the whole orbital data. CrIS-VIIRS CrIS and VIIRS have a general agreement of 0.4K or better.

  7. Task 3: Inter-Sensor Comparison CrISvs. GOES AIRS/CrIS Under the GSICS framework, CrIS, AIRS, and IASI are routinely compared with GOES imager, which will help for GOES imager calibration. Courtesy of Fangfang Yu, STAR/GSICS Inter-calibration results among CrIS-GOES, AIRS-GOES, and IASI-GOES agree well.

  8. Task 4: Measurement Assessment by CRTMCrIS and IASI double difference Over 400,000 data points Double Difference Clear Sky over Ocean Double difference of CrIS and IASI relative to CRTM calculated radiance are within ±0.2 K for most of channels.

  9. Task 4: Measurement Assessment by CRTMInter-FOV difference CrIS Inter-FOV Consistency Over 100,000 data points FOV-2-FOV variability is small, within ±0.2 K for all the channels

  10. Task 5: Spectral Calibration Spectral Uncertainties characterized by CRTM Cross-correlation Method under Clear Sky between Observation and CRTM Simulation MWIR LWIR - FOV spectral calibration is consistent within 1ppm - Spectral calibration has 3ppm offset wrt CRTM for LWIR, and 4ppm offset for MWIR (both meet requirement)

  11. Spectral Shift Caused by Earth-rotation Doppler Effect • Task 5: Spectral Calibration • Doppler Effects in CrIS SDR data Doppler shift: ν :channel frequency; Ω: Earth angular velocity Rs: Distance of the satellite from the center of the Earth i : Inclination of the orbit; λ: Latitude Ф: Scan angle FOR15 relative to FOR16 FOR1 frequency shift relative to FOR30 FOR1 relative to FOR30 The Earth-rotation Doppler effect can cause a channel frequency bias up to 1.3 ppm Very stable CrIS performance allowing detection of very small frequency shifts

  12. Task 6: Geolocation AssessmentUsing VIIRS as a reference Original Collocation at (0, 0) Collocation after shift at minimum of cost function - 3.5 Km cross track and -2.7 Km along track are found in CrIS SDR data - Root cause was found to be a coding error.

  13. Task 6: Geolocation AssessmentBefore and After correction • Software bug was discovered in the operational code. • Code fix was engineered by STAR and delivered to IDPS for implementation. Without correction With correction CrIS CrIS-VIIRS CrIS-VIIRS • Geolocation code has been fixed and implemented in MX6.3 (10/16/2012) • Geolocation accuracy is estimated to be 1.0 km within 30° scan angles.

  14. Task 7: Algorithm/software Improvement Time Stamp Error in SDR codes Incorrect radiance of all bands, all FOVs and all scenes caused by the time stamp coding error with respect to the change of month. LW radiance before fix LW radiance after fix Code fix (in red) in /ADL/SDR/CrIS/src/SystemTimeUtilities.cpp UInt16 leftDays = CcsdsSecondaryHeader::numDaysSinceJanuary1_1958(&leftOperand); UInt16 rightDays = CcsdsSecondaryHeader::numDaysSinceJanuary1_1958(&rightOperand); UInt32 leftMils = (((((((leftDays * HOURS_PER_DAY) + … UInt32 rightMils =(((((((rightDays * HOURS_PER_DAY) + … • STAR fixed the code error and delivered it to IDPS. • It will be implemented in MX7.0 (April 2013).

  15. Task 7: Algorithm/software Improvement: Processing Full Spectra • “Truncation” code to process high resolution RDR and produce low resolution SDR developed at STAR using ADL4.0. Two files were modified: ProSdrCris.cpp and ProSdrCris.h • One step processing (changes are done in memory) • Code given to IDPS for future implementation. Hi-Res RDR Read RDR Modify Processing Parameters Truncate IFGM Low-Res SDR Replace truncated IFGM into CCSDS Pkt Continue SDR processing at Low-Res CrIS AIRS

  16. Task 7: Algorithm/software Improvement: New Quality Flag based on Imaginary Parts - New DQF based on the imaginary part of the spectrum is an excellent indicator of the quality of the real part. - This DQF is now implemented as part of MX 6.3 (October 16th 2012). September 25th 2012 (Ascending) The abnormal imaginary part radiance will be used as a basis for a new pixel-level quality flag, available on October 16th, 2012 With contributions from other team members

  17. Task 7: Algorithm and Software/Improvement Overall Data Quality Flag Improvement • The Beta product has 60% of the SDRs labeled Degraded • CrIS Overall DQF fixed with threshold parameters tuning and code changes. • Last change is related to the new Stage cooler 2 temperature drift limit (4.0K instead of 1.0K). This change will be part of EngPkt V35 tentatively effective on October 22nd. June 13th 2012 (Beta), EngPkt V33 October 13th 2012, MX6.2, EngPkt V34 With contributions from other team members

  18. Discrepancy Report (DR) StatusClosed • These DRs were identified as major and prioritized accordingly. • - Since April 2012 (BETA), all high priority DRs have been closed allowing to achieve the Provisional status.

  19. Discrepancy Report (DR) StatusOn-going or Open

  20. Discrepancy Report (DR) StatusOn-going or Open • The remaining open DRs are minor. • - DPE/DPA and NOAA-STAR agree that these remaining • DRs are not needed for provisional status.

  21. Issues and Challenges • SW cold scene FOV-to-FOV difference. • Spectral (un-apodized) ringing. • Operational ground data system instability causing one week of bad radiance product (May 30th to June 7th). Problem was not replicated and root cause is unknown. • FCE detection/correction module was turned off • Although, currently missing the component in the Ops code does not pose a significant problem as the FCE is a rare event up to now, but there is no guarantee that it will not be a problem in the future. • Software bug fixes and possibly some algorithm redesign are needed, which require a large team effort. • Inefficient and ineffective code changing process, causing delays and uncertainties of algorithm and software fixes and updates. • Augment the code with diagnostic products that allows extraction of key internal values such as raw spectra, temperatures, and many others.

  22. FY-13 Schedule and Milestones • STAR’s responsibility for changing EngPkt parameters and its upload, v35 Oct. 20, 2012 • CrIS SDR user guide, December 2012 • Tools for trending and monitoring radiance differences between CrIS and IASI/AIRS/VIIRS, March 2013 • Geolocation uncertainty trending and monitoring tool, March 2013 • STAR CrIS SDR processor (IDL code): CrISInterferometry Transformation System (CITS), March 2013 • Spectral uncertainty trending and monitoring tool, June 2013 • RDR generator, September 2013

  23. Summary of SDR Uncertainty

  24. Summary • CrIS and IASI have excellent radiometric agreement. • CrIS data and CRTM have a 3ppm spectral calibration offset in LW. • NOAA-STAR fixed the geolocation calculations. • The high priority DRs have been addressed, now focusing on lower priority DRs. • NOAA-STAR assessment is that the CrIS SDR product is ready to be declared provisional.

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