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Monitoring of IR Clear-Sky Radiances over Oceans for SST Xingming Liang 1,2 , Sasha Ignatov 1 and Korak Saha 1,2 1 NOAA/NESDIS/STAR 2 CSU/CIRA. http://www.star.nesdis.noaa.gov/sod/sst/micros/. SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013.

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  1. Monitoring of IR Clear-Sky Radiances over Oceans for SSTXingming Liang1,2, Sasha Ignatov1 and Korak Saha1,21NOAA/NESDIS/STAR 2CSU/CIRA http://www.star.nesdis.noaa.gov/sod/sst/micros/ SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 1 of 32

  2. Acknowledgments Advanced Clear-Sky Processor for Oceans (ACSPO; NESDIS SST System): Sensor Radiances over Oceans with Clear-Sky Mask and QC J. Sapper, Y. Kihai, B. Petrenko, J. Stroup, P. Dash, F. Xu, M. Bouali, X. Zhou – NESDIS SST Team Community Radiative Transfer Model (CRTM) implemented in ACSPO F. Weng, Y. Chen, P. Van Delst, Q. Liu, D. Groff, E. Borbas, C. Mueller – CRTM Team AVHRR, MODIS, VIIRS Characterization & Cross-platform Consistency, including Double Differences (DD): Global Space-based Inter-Calibration System (GSICS) F. Wu, F. Yu, L. Wang, F. Weng, C. Cao, J. Xiong, M. Goldberg, T. Hewison, X. Hu, T. Chang – GSICS Team Simon Hook – NASA/JPL SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 2 of 32

  3. Outline MICROS System Overview MICROS Applications Satellite Radiances Bias Monitoring Web Sites Conclusion Future Plans SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 3 of 32

  4. MICROS Overview • MICROS Objectives • Sensors Monitored in MICROS • System Set-up & Processing Time • MICROS Functionalities SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 4 of 32

  5. MICROS Objectives Understand & Minimize M-O Biases in BT & SST Minimize the Need for Empirical “Bias Correction” Evaluate Sensor Radiances for Stability Check for Cross-Platform Consistency Monitor clear-sky sensor radiances (BTs) over global ocean in NRT (“OBS”) , against CRTM with first-guess input fields (“Model”) SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 5 of 32

  6. Platforms/Sensors in MICROS • Processing several AVHRRs from Jul’2008-on • Metop-A (FRAC-1km and GAC-4km) – Stable • NOAA19 (GAC) – Stable • NOAA18 (GAC) – Somewhat unstable • NOAA17 (GAC) – Scan Motor Stalled in Feb’2010 • NOAA16 (GAC) – Out of family, likely subject to Cal issues • Added in Jan’2012 • NPP/VIIRS (0.75km) - Stable • Terra/MODIS (1km) - Stable • Aqua/MODIS (1km) - Stable • Added in Sep’ 2012 • Metop-B (FRAC-1km and GAC-4km) – Stable • In pipeline • Geo sensors: MSG/SEVIRI, GOES-R/ABI • Leo sensors: ERS/(A)ATSR SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 6 of 32

  7. SST Bands • Only clear-sky ocean BTs @ 3.7, 11 and 12 µm for AVHRR, MODIS and VIIRS are used in this study • Adding optional bands is underway SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 7 of 32

  8. ACSPO/MICROS Processing • ACSPO: Advanced Clear-Sky Processor for Oceans • Operational at NOAA since May 2008 • Generates clear-sky radiances, SSTs and AODs in AVHRR like bands • Integrated CRTM generates model BTs with first guess fields: • SST: Reynolds 0.25° SST • Upper Air: NCEP GFS 1° fields # of clear-sky Night ocean pixels and Processing Time for 24hrs of L1b data SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 8 of 32

  9. Data Availability (Jun’2012 – on) • Data Availability is used in MICROS to monitor ACSPO real-time data processing status SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 9 of 32

  10. MICROS Highlights MICROS • Statistical analyses performed in global clear-sky ocean domain • End-to-end system • Web-based NRT tool • Both conventional & robust statistics used • Analyses separated by Day/Night • Only Night data used for SDR analyses • Presently, daytime data not used due to sub-optimal treatment of solar reflectance & diurnal cycle • Double-differences used to evaluate sensor radiances for cross-platform consistency • Interactive function are used for flexible cross-platform inter-comparison SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 10 of 32

  11. MICROS Functionalities Maps Four ways to present M-O Biases in MICROS Histograms Time series Dependencies System information menu provides: Real-time data processing status, Product data download, and MICROS version update history SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 11 of 32

  12. Global Daily Maps @ 28 Jan 2013 METOP-B FRAC NPP VIIRS TERRA MODIS AQUA MODIS • The M-O biases: Close to zero; Uniformly distributed SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 12 of 32

  13. Global Histograms AVHRR GAC High Resolution 3.7 µm 3.7 µm • Shapes are close to Gaussian. M-O bias is slightly positive. • More clear-sky pixels generated from high res. sensors, especially VIIRS (~100 Mln/Night) • 4 AVHRRs (Metop-A, NOAA-16, -18 and -19), VIIRS, Terra MODIS consistent to within ~0.1 K • Terra and Aqua inconsistency: ~0.3 K • Metop-A and -B inconsistency: ~0.15 K • Cross-platform inconsistencies may be due to • Overpass times from 9:30pm-5am – M-O Biases subject to Diurnal Effects • Errors in sensor calibrations • Errors due to real spectral response differences, or inconsistent CRTM coefficients SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 13 of 32

  14. Time Series of M-O Bias N16: unstable and out of family N17: Scan motor spiked in Feb’2010 M-O biases systematically differ between Metop-A and -B, and Terra and Aqua • Warm M-O biases are due to: • Missing aerosols; Using bulk SST instead of skin; Using daily mean Reynolds SST to represent nighttime SST; Residual cloud • Temporal variability is consistent for different platforms, and mainly due to unstable Reynolds SST input to CRTM SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 14 of 32

  15. View Zenith Dependencies View Angle dependencies of mean bias: Close to zero; RSD: ~ 0.4 K MICROS provide 11 dependencies of M-O bias, SD, and NOBS for different geographical and environmental parameters SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 15 of 32

  16. MICROS Applications • Diagnostics of ACSPO SST products • Including Check for Ambient Clear-Sky Performance • Monitor sensor radiances • Using Double Differences (DD) to Evaluate Sensor Radiances for Stability and Cross-Sensor Consistency • Validate and improve CRTM • Including Input Fields of SST & Atmospheric Profiles SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 16 of 32

  17. Diagnostics of ACSPO - 1 ACSPO Improvements CRTM r577 CRTM r577 ACSPO V1.0 + weekly SST ACSPO V1.0 + Daily SST ACSPO V1.0 + weekly SST ACSPO V1.0 + Daily SST CRTM V1.1, Daily V.1 SST CRTM V1.1, Daily V.1 SST ACSPO V1.02 ACSPO V1.10 ACSPO V1.02 ACSPO V1.10 Liang, X., and A. Ignatov. Monitoring of IR Clear-sky Radiances over Oceans for SST (MICROS). JAOT 28, 2011 • ACSPO version update gradually reduce SDs and improve VZA dependencies • ACSPO cloud mask is robust with respect to CRTM and its input SST team has released ~10 ACSPO versions since 2008. All versions tested in MICROS before they are released. SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 17 of 32

  18. Diagnostics of ACSPO – 2 Ambient Clear-Sky Check Exponential Fit: IR37 • NCSOP -> ∞, M-O -> A • NCSOP -> 0, M-O -> A+B • B: Amplitude of M-O bias • C: Drop-off rate IR11 • NCSOP in 25 x25 window central at clear-sky pixel is used • M-O bias changes significantly from “cloudy” to “confident clear-sky” • These analyses may be helpful to guide improvement to ACSPO cloud mask, validate CRTM and its input • AC Deps. has been added in MICROS. • A more flexible fitting technique is currently being developed IR12 Center CS pixel Liang, et al., Implementation of the Community Radiative Transfer Model (CRTM) in Advanced Clear-Sky Processor for Oceans (ACSPO) and validation against nighttime AVHRR radiances. JGR,114, 2009 SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 18 of 32

  19. Monitor Sensor Radiances - 1Double Differences (DD) • Day-to-day noise and spurious variability hinder accurate measurement of cross-platform bias • Double-differences (DD) employed to differentiate the “cross-platform bias” signal from “noise” • CRTM (Reynolds SST) is used as a ‘Transfer Standard’ • DDs cancel out/minimize effect of systematic errors & instabilities in BTs and SSTs arising from e.g.: • Errors/Instabilities in reference SST & GFS • Missing aerosol • Possible systemic biases in CRTM • Assuming consistent CRTM are used in both SAT and REF. • Updates to ACSPO algorithm SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 19 of 32

  20. Monitor Sensor Radiances - 2 Night DD’s @11 µm (Ref=Metop-A GAC) CRTM V2.1 implemented N16: unstable and out of family Metop-B: out of family VIIRS recalibration Liang, Ignatov: Stability & Radiometric Consistency between AVHRR, MODIS, and VIIRS in SST bands. JGR, 2013, submitted • All AVHRRs and NPP/VIIRS are consistent to within ±0.1K • VIIRS Cal change 7 Mar 2012 reset BT@M15 by +0.14K – now better in family • Terra and Aqua/MODIS out of family by 0.6K – due to suboptimal CRTM coefficients in V2.02 • Both were back in family after CRTM V2.1 implemented on Sep. 13, 2012 • Metop-A and –B are inconsistent by ~0.3 K, due to suboptimal CRTM coefficients used in CRTM V2.1. SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 20 of 32

  21. Monitor sensor radiances - 3 Nighttime DD’s SST (Ref=Metop-A GAC) CRTM V2.1 implemented New Reg. Coeff. used VIIRS recalibration N16: unstable and out of family • All AVHRRs, MODISs and NPP/VIIRS SSTs are consistent to within ±0.1K • VIIRS Cal Change 7 Mar 2012: SST +0.10K – Out of family • New SST coefficients implemented 3 May 2012: SST -0.15K – Back in family • CRTM update resulted regression SSTs more noise, and the new coefficients have been implemented since Dec. 2012. More data is needed to understand their performance. SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 21 of 32

  22. Monitor sensor radiances – 4 Understand/Fix Biases not Cancelled out in DDs • Systemic biases should cancel out in DDs for different spectral response function (SRF) • However, DDs can not cancel out systemic biases if Inconsistent CRTM calculations were used (cf. slide 21) • Work is underway between SST, CRTM, and sensor calibration Teams to • Generate uniform CRTM Coefficients • Understand SRF effect on DDs SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 22 of 32

  23. Validate and improve CRTM - 1Sensitivity to input SST Reynolds OSTIA Fewer spurious variations when OSTIA SST is used Smaller STD: OSTIA captures spatial SST variability better than Reynolds Median (M-O) DDs improve only slightly (input SST largely cancels out) Robust STD (M-O) Selection of first guess SST is critical for accurate TOA first-guess radiances Double Differences Liang, X., and A. Ignatov. Monitoring of IR Clear-sky Radiances over Oceans for SST (MICROS). JAOT 28, 2011 SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 23 of 32

  24. Validate and improve CRTM - 2 Selection of First guess SST Saha, Ignatov, Liang, and Dash, Selecting a first-guess SST field as input to forward RTM, JGR, 117, 2012 • Cross-evaluate* eleven L4 SST fields, using ACSPO L2 as a “transfer standard” • μ(μΔε) ~ ±70mK and σ(μΔε)~35mK (except ODYSSEA); μ(σΔε) < 500mK and σ(σΔε) ~ 25mK • The GHRSST Multi-Product Ensemble (GMPE) and Canadian Meteorological Centre analysis (CMC), show better consistency with ACSPO L2 SST • GMPE or CMC will be explored as first-guess SST in next ACSPO Version SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion. 5-7 March 2013 Slide 24 of 32

  25. Validate and Improve CRTM - 3Improve daytime CRTM performance CRTM V1.1 • Quasi-Lambertian surfacemodel used in CRTM v1 caused unrealistic cold M-O bias ~-20 K in sun glint and a smaller warm bias ~+5 K outside glint in 3.7µm band • Using specular reflectance model improves daytime M-O biases. • Based on MICROS analyses, CRTM v2 employs improved solar reflectance model • Cox-Munk empirical will be fine-tuned to minimize the remaining M-O bias CRTM V2.0 Liang, and Ignatov. Validation and Improvements of Daytime CRTM Performance Using AVHRR IR 3.7 um Band. 13th AMS Conf. Atm. Radiation, Portland, OR, 2010 SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 25 of 32

  26. Validate and improve CRTM - 4Fixing CRTM treatment of out of band response in N16 Ch3B CRTM V1.1 out of band leakage CRTM r577 Liu, et al., Effect of out-of-band response in NOAA-16 AVHRR Channel 3B on top-of-atmosphere radiances calculated with the Community Radiative Transfer Model. JAOT, 26, 2009 • NOAA16 Ch3B is 0.3 K was out of family when using CRTM r577 • This anomaly is due to the combination of three effects • Out of band leakage in Ch3B • No data above 10hPa in GFS • In CRTM r577, temp profile above 10hPa extrapolated incorrectly • The extrapolation was fixed in CRTM v1.1 SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 26 of 32

  27. Other Satellite Radiances Bias Monitoring Web Sites ECMWF Satellite Data (GEO radiances) Monitoring Web site http://www.ecmwf.int/products/forecasts/d/charts/monitoring/satellite/ EUMETSAT GSICS Bias web site http://www.eumetsat.int/Home/Main/DataProducts/Calibration/Inter-calibration/GSICSBiasMeteosatIRInter-calibration/index.htm?l=en NESDIS/STAR Satellite Integrated Calibration / Validation System (ICVS) http://www.star.nesdis.noaa.gov/smcd/spb/icvs/ JMA GSICS Bias web site http://mscweb.kishou.go.jp/monitoring/gsics/ir/gsir_mt1r.htm SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 27 of 32

  28. Conclusion • MICROS used to monitor M-O bias • End-To-End, Near-Real Time, Web-Based System • Functional with5 AVHRR, 2 MODIS, and VIIRS • Diagnostics of ACSPO SST products • All ACSPO versions are tested in MICROS before official release • All performance metrics improve from version to version • Monitoring of sensor stability and cross-consistency • Generally, BT and SST biases in-family & stable (except for N16) • Double Differences cancel out most errors/noise in M-O biases • Cross-platform DDs ~several 10-2K (errors in CAL, SRFs or CRTM coefficients) • Validation and improvements to CRTM and its input • Variability in M-O biases due to unstable Reynolds SST, GMPE is selected as first-guess SST in next ACSPO Version • Specular reflectance model significantly improve daytime performances. SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 28 of 32

  29. Future Plans - 1 Improve MICROS M-O Biases and DDs • SST, CRTM, Sensor Cal Teams Work Together to • Generate Uniform CRTM Coefficients to Improve DDs • Understand & Minimize SRF effect on DDs • Improve Accuracy of MICROS DDs • Use More Accurate First Guess Fields (SST, Profiles) • Improve ACSPO Cloud Mask • Improve CRTM Accuracy (in particular, daytime) • Understand and Minimize Cross-Platform Biases • Add Aerosol in CRTM • Model Diurnal Variation (DV) in Global First-Guess SST Input to CRTM • Improve Sensor Radiances (Calibration, Spectral Response Functions) SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 29 of 32

  30. Future Plans - 2 Extend MICROS to Include Visible Bands • Aerosol Quality Monitor (AQUAM) is being set up to prepare for adding aerosol in CRTM • GOCART and NAAPS initially selected as two prospective inputs into CRTM • Initially, use solar reflectance bands to evaluate CRTM/GOCART&NAAPS • First-guess reflectances will improve ACSPO clear-sky mask • Subsequently, extend aerosol analyses into thermal IR bands • M-O bias in thermal bands will become closer to zero & STD reduced SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 30 of 32

  31. Future Plans - 3 Add GEO & New Polar Sensors • MSG SEVIRI: In progress • (A)ATSR: Part of NASA cross-calibration proposal • GOES-R/ABI (~2016) SST from polar orbiters: use of NWP outputs, OSI-SAF WORKSHOP, Lannion 5-7 March 2013 Slide 31 of 32

  32. Thank you! SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 32 of 32

  33. Nighttime DD’s @12 µm (Ref=Metop-A GAC) CRTM V2.1 implemented VIIRS recalibration N16: unstable and out of family • All AVHRRs and NPP/VIIRS are consistent to within ±0.1K • VIIRS Cal Change 7 Mar 2012 reset BT@M16 +0.14K – now better in family • Terra and Aqua/MODIS out of family by 0.3K – due to suboptimal CRTM coefficients in V2.02 • Both were back in family after CRTM V2.1 implemented on Sep. 13, 2012 SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 33 of 22

  34. Quasi-Lambertianvs BRDF CRTM V1.1 AVHRR BT CRTM V2.0 SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 34 of 32

  35. Monitor Sensor Radiances - 2 Night DD’s @3.7 µm (Ref=Metop-A GAC) VIIRS recalibration CRTM V2.1 implemented N16: unstable and out of family • All AVHRRs, Terra/MODIS, and NPP/VIIRS are consistent to within ±0.1K • VIIRS Cal Change 7 Mar 2012 reset BT@M12 by +0.14K; Remains in-family • Terra was in AVHRR/VIIRS family, but Aqua was biased by ~0.3 K when CRTM V2.02 used. • They were shifted by +0.06 and +0.09 K when CRTM V2.1 was implemented on Sep. 13, 2012. • Metop-A and –B are inconsistent by ~0.17 K, partly due to suboptimal CRTM coeffs. in CRTM V2.1. SST from polar orbiters: Use of NWP outputs, OSI-SAF WORKSHOP, Lannion, 5-7 March 2013 Slide 35 of 32

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