1. CLARREO FTS Design: Achieving Robust On-Orbit SI Traceability for IR - Principles Distilled from NIST John A. Dykema, Joe Demusz, Chris Tuozzolo, Norton Allen, James G. Anderson, Harvard Hank Revercomb, Fred Best, P. Jonathan Gero, Joe Taylor, Bob Knuteson, Dave Tobin, Bob Holz, UW Jerry Fraser, Eric Shirley Sergey Mekhontsev, Leonard Hanssen, Vladimir Khromchenko NIST

2. NRC DS and CLARREO “a long-term global benchmark record of critical climate variables that are accurate over very long time periods, can be tested for systematic errors by future generations, are unaffected by interruption, and are pinned to international standards” CLARREO science team: -High information content -High accuracy, proven on-orbit -Sampling errors in time, angle, space lower than climate noise

3. What is SI Traceability? SI traceability is conferred by a chain of comparisons, each of stated uncertainty, back to a recognized SI standard CLARREO needs to: –have uncertainty low enough for decadal science and –needs to prove that biases (systematic error) that specify this uncertainty are within tolerances

4. SI Traceability and CLARREO Jerry Fraser (NIST) has introduced the idea of strength of SI traceability claim NIST would recognize that CLARREO requires robust traceability to achieve its ambitious science goals

5. The National Measurement Institute (NMI) Model for Traceability Measurements are Based on Well-Defined Physical Quantities Measurements are Compared among NMIs Measurements are Compare to Independent Approaches Uncertainty Claims are Rigorous and Validated Methods are Documented in Quality Systems and Peer-Reviewed Publications Research is Undertaken to Lower Uncertainties Fundamental Scales are Realized Periodically From Jerry Fraser, NIST

7. Plan for suggested CLARREO IR Evaluation at NIST Metrology activityNIST facilityBias source Measurement of surface BRDFFTISBlackbody emissivity Computation of blackbody emissivity from measured BRDFSTEEP-3Blackbody emissivity Modeling of blackbody cavity emissivity monitorSTEEP-3Blackbody emissivity Measurement of blackbody emissivity (1)CHILRBlackbody emissivity Measurement of blackbody emissivity (2)AIRI scene plateBlackbody emissivity Evaluation of on-orbit emissivity monitorAIRI, CHILRBlackbody emissivity Measurement of blackbody radianceAIRIBlackbody emissivity, temperature Measurement of blackbody radiance over wide temperature range (~190 to ~320 K)OARS (UW): tested as aboveNonlinearity Measurement of uniform, monochromatic sourceOSRM (Harvard)Spectral calibration (ILS) Viewing tested blackbodies with controlled, varied backgroundCBSStray light Viewing tested blackbodies with controlled, varied background at different positionsCBSPolarization Viewing primary BB sourcesNIST primary BB sourcesSystem-level

8. Envisioned NIST Infrared Metrology Support The case study involved elements in red

9. Case Study: Goals 1Characterize Blackbody Spectral Emissivity using AIRI Facility -Infrared spectral radiance measurements compared to Reference Blackbodies -Use controlled background “scene plate”; also characterize spectral radiance uniformity 2Characterize Blackbody Cavity Emissivity using Sphere Reflectometer (CHILR) -Lasers used for low divergence, small spot, high power, 1.32 µm & 10.6 µm -Custom sphere for complete measurement of cavity reflected light 3Model Blackbody Cavity Emissivity using characterized cavity coating properties: A.Spectral directional hemispherical reflectance (FTIS Facility) -Near-normal - Reference Integrating Sphere with Fourier Transform IR Spectrometer -Variable angle - Center Mount Sphere with FTIR B. Cavity Coating BRDF, Bi-directional reflectance distribution function (IR SIRCUS / BRDF) -Laser-based system, 1.55 µm & 10.6 µm C.Monte Carlo Raytrace Modeling of Blackbody Cavity -Custom Cavity Modeling Software Suite, “STEEP3” and upgraded / modified versions -Requires cavity coating properties data

10. - ArtifactsCase Study - Involved Facilities Complete Hemispherical Laser-based Reflectometer (CHILR) Fourier Transform Spectrophotometry (FTS) and IR BRDF Facilities Advanced Infrared Radiometry and Imaging Facility (AIRI)

11. Case Study: Results of Cavity Emissivity from Reflectance, Radiance, and Modeling Blackbody Cavity Laser Reflecto- metry (CHILR) Thermal Reflecto- metry (AIRI) Absolute Radiance (AIRI) Modeling (STEEP-3) SSEC-AERI0.99940.99900.99960.9993 HU Cone0.99820.9983n/a0.9964 HU 1 Section0.99960>0.9996n/a0.99942 HU 2 Section0.99985n/a 0.99978 HU 3 Section0.99991>0.9998n/a0.99989

12. On-orbit Traceability for Blackbody 1 NIST: CBS-3  : reflectometry, scene plate  T: contact, fixed point On-orbit diagnostics:  : Reflectometer (QCL 2, halo)  T: phase change cells 3,4 1.Dykema and Anderson, Metrologia 43 287-293 (2006). 2.Gero, et al., in press, J.TECH. (2009). 3.Gero, et al., J.TECH. 25 (2008). 4.Best et al., GC23A- 0753.

13. Emissivity / QC Power Evaluation dT/dt = 5 x 10 -5 K/sec Lab result: C(dT/dt)=35 mW P QC (measured)=33mW

14. Primary Demonstration of SI Traceability (used in combination with space view for instrument calibration) (used for blackbody reflectivity and Spectral Response Module) (Includes Multiple Phase Change Cells for absolute temperature calibration and Heated Halo for spectral reflectance measurement ) Heated Halo (Measures instrument line shape) QCL Laser

15. How to prove uncertainty is consistent with what is claimed? (NIST perspective) From Joe Rice, NIST

16. 1 st Sensor 2 nd Sensor 1 st Sensor 2 nd Sensor CLARREO solution: two complete, independent test sensors with independent Test/Validation modules

17. Advantages to Dual Interferometers Testing uncertainty on cold scenes that can’t reliably produced in laboratory High duty cycle available for systematic error testing without disturbing benchmark Testing systematic error by perturbing thermal or stray light environment Optimization of radiometric performance for far- and mid- IR Testing blackbody knowledge through thermal gradient perturbation Agreement between two instruments invaluable in proving uncertainty is consistent with claims

18. Lessons Learned QCL reflectometer paper to peer review: improve laser power normalization NIST demonstration study: demands different blackbody control design Iteration/communication between science and engineering: getting dual interferometers into trade space, looking for realistic path

19. The National Measurement Institute (NMI) Model for Traceability Measurements are Based on Well-Defined Physical Quantities Measurements are Compared among NMIs Measurements are Compare to Independent Approaches Uncertainty Claims are Rigorous and Validated Methods are Documented in Quality Systems and Peer-Reviewed Publications Research is Undertaken to Lower Uncertainties Fundamental Scales are Realized Periodically CLARREO flight designs must be evaluated against the logic of these principles