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 1

Tasks Performed at STAR Task NameDescriptionStatus 1.ManagementManagerial and technical leadContinuous activity 2. Trending and MonitoringMonitor the instrument, RDR and SDR data quality Functional, continuous activity 3. Inter-sensor comparisonCrIS with IASI, AIRS, and VIIRS; CrIS/IASI/AIRS with GOES Provisional status 4. Measurement assessment by CRTM Double Difference of CrIS vs. IASI; CrIS inter-FOV consistency Provisional status. 5. Spectral UncertaintyCross correlation methodOn-going 6. Geolocation AssessmentUsing VIIRS as baseline.Bug fixed; Continue monitoring 7. Algorithm and software improvement DR investigation and bug fix. High resolution RDR Processing. On-going 2

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. 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: Measured laser wavelength shows downward trend since 09/2012 ; the CMO will be re-calculate when wavelength drift exceeds the threshold.

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

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

Task 3: Inter-Sensor Comparison CrIS vs. VIIRS 6 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 and VIIRS have a general agreement of 0.4K or better. NEdT large at low temperature CrIS-VIIRS

Task 3: Inter-Sensor Comparison CrIS vs. GOES Inter-calibration results among CrIS-GOES, AIRS-GOES, and IASI-GOES agree well. 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

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

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

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

Spectral Shift Caused by Earth-rotation Doppler Effect 11 Doppler shift: ν : channel frequency; Ω: Earth angular velocity R s : Distance of the satellite from the center of the Earth i : Inclination of the orbit; λ: Latitude Ф: Scan angle 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 FOR1 frequency shift relative to FOR30 FOR1 relative to FOR30 FOR15 relative to FOR16 Task 5: Spectral Calibration Doppler Effects in CrIS SDR data

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

Software bug was discovered in the operational code. Code fix was engineered by STAR and delivered to IDPS for implementation 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. Task 6: Geolocation Assessment Before and After correction Without correction With correction CrIS CrIS-VIIRS

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

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. CrIS AIRS Hi-Res RDR Low-Res SDR Read RDR Modify Processing Parameters Truncate IFGM Replace truncated IFGM into CCSDS Pkt Continue SDR processing at Low-Res

Task 7: Algorithm/software Improvement: New Quality Flag based on Imaginary Parts 16 September 25 th 2012 (Ascending) The abnormal imaginary part radiance will be used as a basis for a new pixel-level quality flag, available on October 16th, 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 16 th 2012). With contributions from other team members

Task 7: Algorithm and Software/Improvement Overall Data Quality Flag Improvement 17 June 13 th 2012 (Beta), EngPkt V33October 13 th 2012, MX6.2, EngPkt V34 With contributions from other team members 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 22 nd.

Discrepancy Report (DR) Status Closed DR Number DescriptionDateStatus 4821Incorrect geolocation calculation07/03/12Closed 4794Make the CMO-EngPkt available to end user06/21/12Closed 4680CrIS Overall DQF set to degraded04/13/12Closed 4661CrIS Overall DQF set to value 304/10/12Closed 4557CrIS IFGM Packets with “Fill” release to RDR/SDR02/06/12Closed 4478CrIS Overall DQF set to invalid for cold Earth scenes12/02/11Closed 18 -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.

Discrepancy Report (DR) Status On-going or Open DR Number DescriptionDateStatus 4941Action for CLASS to distribute the CMO-EngPkt file10/03/12On-going 4909Scan anomaly (time stamp issue)09/21/12On-going 4812Add a flag indicating the CMO values have changed06/28/12On-going 4774Corrupted CMO matrix leading with radiance with zero values (May 30 th –June 7 th radiance anomaly 06/11/12Approved for future evaluation 4508Earth spectra quality flag set to degraded when FCE detected 12/22/11Approved for future evaluation 4481FCE correction algorithm does not work for cold Earth scenes. (substantial level of effort). 12/06/11On-going 4407Inconsistency with serialization (related to CMO archiving) 10/19/11open 19

DR Number DescriptionDateStatus 4391Some Interferogram.cpp operators need to be updated10/13/11Open 4389Earth scene ZPD magnitude data type field inconsistencies 10/13/11Open 20 Discrepancy Report (DR) Status On-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.

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 30 th to June 7 th ). 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. 21

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): CrIS Interferometry Transformation System (CITS), March 2013 Spectral uncertainty trending and monitoring tool, June 2013 RDR generator, September

Summary of SDR Uncertainty MethodResultRequirement Radiometric Assessment -SNO CrIS vs AIRS/IASI -Double difference -GEO SNO match 0.4K or better DD match 0.2K or better 0.3K or better 0.45% LW 0.58% MW 0.77% SW at 287K BB. Radiometric Assessment -Double Difference 0.2K or betterSame as above Radiometric Assessment -GEO vs LEO0.3K or betterSame as above Spectral Calibration Using CRTM3 ppm LW 4-5 ppm MW < 10 ppm Geolocation Accuracy CrIS vs VIIRS1.0Km accuracy at nadir 1.5 Km 23

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. 24