CLARREO: Radiometric Concept and Requirements

1. CLARREO: Radiometric Concept and Requirements John A. Dykema, P. Jonathan Gero, Stephen S. Leroy, James G. Andeson Harvard University Major contributions: University of Wisconsin (SSEC) National Institutes of Standards and Technology

2. SI traceable standards Technology and strategy for establishing absolute scales Innovation for detection of systematic errors Atomic clocks, phase transition cells, frequency stabilized lasers Accuracy, precision and bias on-orbit Blackbodies, frequency standards, temperature cells Quantum cascade lasers, linear detectors, polarization of optical systems in space Targets for calibration: Moon, stars, etc. Important Sub-fields Related to High Accuracy Long-term Climate Records Optical Systems for High Accuracy Observations from Space Metrology Climate Community and Climate Records • Ground-based observations • Sondes, GEOS • Use of weather data for climate • Intercomparison methods between satellites • In-situ intercomparisons NIST ASIC3 IPCC, GEOSS Dykema et al.: CLARREO Radiometric Concept and ...

3. NIST Standards to Tie On-orbit Measurements to International Standards Source: Sergey Mekhontsev, NIST Dykema et al.: CLARREO Radiometric Concept and ...

4. Keeling curve Monthly mean CO2 concentration at Mauna Loa, HawaiiObservations started by C. D. Keeling in 1958 NOAA Global Monitoring Division

5. Figure 14 The 28-year Total Solar Irradiance record comes from several overlapping instruments. Offsets are due to inconsistent absolute accuracies, although each instrument precisely monitors short-term TSI changes. None of these instruments is calibrated end-to-end for irradiance at the desired absolute accuracy levels, as no such facility currently exists. The error bar shown indicates 0.1 % variation. Dykema et al.: CLARREO Radiometric Concept and ...

6. Current Measurements Inhibit Application of the Scientific Method Dykema et al.: CLARREO Radiometric Concept and ...

7. Dykema et al.: CLARREO Radiometric Concept and ...

8. Requirements • 0.1 K at 750 cm-1 and 250 K target (3-s) • Far-IR to near-IR (100-200 cm-1 to 2500-3300 cm-1) • 1 cm path difference (~0.6 cm-1) resolution Dykema et al.: CLARREO Radiometric Concept and ...

9. Achieving SI traceability • The SI traceability of a radiometric measurement may be determined only when multiple (redundant) SI traceable standards are available: • Pollock, D. B., T. L. Murdock, R. U. Datla, and A. Thompson, Data uncertainty traced to SI units. Results reported in the International System of Units, International Journal of Remote Sensing, 24(2), 225-235, 2003. • Previous SI standards based on well-founded physical principles were subject to irreconcilable drifts; for example, electrochemical cells for the standard volt, revealed only by quantum electrical standards. - Hartland, A., Quantum Standards for Electrical Units, Contemporary Physics, 29(5), 477-498, 1988. Dykema et al.: CLARREO Radiometric Concept and ...

10. Quantifying Systematic Uncertainties On-Orbit The Foundations of the Infrared SI Scale • ASIC-3 report: “If an observation is not initially SI traceable against an absolute scale, it cannot engage in the logic of testing for systematic error. ” • Martin, J. E., and P. R. Haycocks, Design considerations for the construction of an absolute radiation detector at the NPL, Metrologia, 35(4), 229-233, 1998. • Quinn, T. J., and J. E. Martin, A Radiometric Determination of the Stefan-Boltzmann Constant and Thermodynamic Temperatures between -40° C and +100° C, Philosophical Transactions of the Royal Society of London Series A- Mathematical, Physical and Engineering Sciences, 316(1536), 85-160, 1985. Dykema et al.: CLARREO Radiometric Concept and ...

11. NIST Standards to Tie On-orbit Measurements to International Standards Source: Sergey Mekhontsev, NIST Dykema et al.: CLARREO Radiometric Concept and ...

12. Tracing the on-orbit calibration to primary standards 1. 2. Detector based Dykema et al.: CLARREO Radiometric Concept and ...

13. K Spectral Infrared Measurements Achieve Traceability via Planck’s Law Dykema et al.: CLARREO Radiometric Concept and ...

14. The Kelvin: 1/273.16 of the triple point of water ITS-90: fixed points define scale relevant to thermal infrared Hg (T.P.) 234.3156 K H2O (T.P.) 273.16 K Ga (M.P.) 302.9146 K Temperature (K) GaIn (M.P.) 288.5 K GaSn (M.P.) 293.5 K GaZn (M.P.) 298.5 K Temperature calibration: thermodynamic, practical Dykema et al.: CLARREO Radiometric Concept and ...

15. Measurement of emissivity – experimental setup Integrating sphere Measurement of EmissivityExperimental setup • Blackbody surfaces characterized with reflectometer • Light source: 8um quantum cascade laser with integrating sphere (Labsphere) • Measurements calibrated with a traceable reference standard

16. Far IR Properties of Coatings From Persky and Blue 1992 Dykema et al.: CLARREO Radiometric Concept and ...

17. Uncertainty (Error) Budget for Infrared Dykema et al.: CLARREO Radiometric Concept and ...

18. SI Temperature On-Orbit: Integration of Phase Transition Cell with Blackbody Dykema et al.: CLARREO Radiometric Concept and ...

19. Determination ofEmissivity On Orbit: Quantum Cascade Laser Dykema et al.: CLARREO Radiometric Concept and ...

20. Determination of Emissivity On Orbit: Heated Scene Tube Dykema et al.: CLARREO Radiometric Concept and ...

21. NIST Standards to Tie On-orbit Measurements to International Standards Source: Sergey Mekhontsev, NIST Dykema et al.: CLARREO Radiometric Concept and ...

22. End-to-End Sensor Evaluation Dykema et al.: CLARREO Radiometric Concept and ...

23. The Multiple Interferometer Dykema et al.: CLARREO Radiometric Concept and ...

24. Conclusions • NIST involvement at every step: • Intellectual Framework • Materials Characterization • Subsystem Testing Full Sensor Evaluation Dykema et al.: CLARREO Radiometric Concept and ...

25. Supporting Materials Dykema et al.: CLARREO Radiometric Concept and ...

26. Diurnal and Semidiurnal Cycles Dykema et al.: CLARREO Radiometric Concept and ...

27. Diurnal Cycle, Window (909 cm-1) GFDL CM2.0, fully coupled Dykema et al.: CLARREO Radiometric Concept and ...

28. Semidiurnal Cycle, Window (909 cm-1) GFDL CM2.0, fully coupled Dykema et al.: CLARREO Radiometric Concept and ...

29. Semidiurnal Cycle (909 cm-1) GOES & TOVS, 3-hourly analysis Salby et al. (1991) Dykema et al.: CLARREO Radiometric Concept and ...

30. Comparison of 90º Polar Orbit, Sun-Synchronous Orbit, Low-Latitude Precessing Orbit Dykema et al.: CLARREO Radiometric Concept and ...

31. Spectral Diurnal Cycle Dykema et al.: CLARREO Radiometric Concept and ...

32. Spectral Semidiurnal Cycle Dykema et al.: CLARREO Radiometric Concept and ...

33. Instrument Line Shape and Spectral Response Function On Orbit: Quantum Cascade Laser and Atmospheric Rotation-Vibration Lines Dykema et al.: CLARREO Radiometric Concept and ...

34. Historical CO2 data 3 Historical CO2 Data Slocum, 1955 NOAA Global Monitoring Division

35. GPS RO: a climate index tied to the atomic clock Dykema et al.: CLARREO Radiometric Concept and ...

36. Calibration: Double Differencing Hardy, K.R., G.A. Hajj, and E.R. Kursinski, 1994: Accuracies of atmospheric profiles obtained from GPS occultations. Int. J. Sat. Comm.,12, 463-473. Dykema et al.: CLARREO Radiometric Concept and ...

37. Achieving SI traceability • The SI traceability of a radiometric measurement may be determined only when multiple (redundant) SI traceable standards are available: • Pollock, D. B., T. L. Murdock, R. U. Datla, and A. Thompson, Data uncertainty traced to SI units. Results reported in the International System of Units, International Journal of Remote Sensing, 24(2), 225-235, 2003. • Previous SI standards based on well-founded physical principles were subject to irreconcilable drifts; for example, electrochemical cells for the standard volt, revealed only by quantum electrical standards. - Hartland, A., Quantum Standards for Electrical Units, Contemporary Physics, 29(5), 477-498, 1988. Dykema et al.: CLARREO Radiometric Concept and ...

38. NIST’s Josephson voltage standard NPL’s cell voltage transfer standard Dykema et al.: CLARREO Radiometric Concept and ...

39. HgCdTe Dykema et al.: CLARREO Radiometric Concept and ...

40. Dykema et al.: CLARREO Radiometric Concept and ...

41. V- V+ Thermistor Lead I- I+ NbTi (superconducting) Heater Leads Copper Mount Gold-Black Coating (Heater and Absorber) Sapphire Layer & Aluminum Film Si Chip Thermistor (Bolometer) Dykema et al.: CLARREO Radiometric Concept and ...

42. The Kelvin: 1/273.16 of the triple point of water ITS-90: fixed points define scale relevant to thermal infrared Hg (T.P.) 234.3156 K H2O (T.P.) 273.16 K Ga (M.P.) 302.9146 K Temperature (K) GaIn (M.P.) 288.5 K GaSn (M.P.) 293.5 K GaZn (M.P.) 298.5 K Temperature calibration: thermodynamic, practical Standard Platinum Resistance Thermometer (SPRT): interpolates between fixed points Dykema et al.: CLARREO Radiometric Concept and ...

43. Why SI traceability? NRC DS: • high accuracy, • tested for systematic errors on-orbit, • and tied to irrefutable standards Dykema et al.: CLARREO Radiometric Concept and ...

44. What is the SI? • Units defined by fundamental properties of matter • Well-established uncertainty estimates • Well-explored relationships to fundamental constants Dykema et al.: CLARREO Radiometric Concept and ...

45. FIG. 10. Results of the satellite merging calculation analogous for the NOAA-11–NOAA-12 overlap period. The gray dots are the NOAA-11–NOAA-12 differences. The black dots represent the fit to the differences using the ocean-only target multipliers. The black crosses are the after-the-fit residuals, offset so that the horizontal line is zero. (a) Merger performed without the diurnal correction. Note the overall slope of the residuals in the 1992–95 time period due to the drift in local crossing time of NOAA-11. (b) Merger performed using the diurnal correction. Note the marked reduction in the slope and the seasonal cycle in the residuals. This provides another check on the validity of the CCM3-based diurnal correction. Dykema et al.: CLARREO Radiometric Concept and ...

46. What is traceability? • Standard definition: “the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties.“ • Easy enough: what constitutes unbroken? Dykema et al.: CLARREO Radiometric Concept and ...

47. Dykema et al.: CLARREO Radiometric Concept and ...

48. Quantifying the SI traceability of an infrared remote sensing measurement • Rice, J. P., and B. C. Johnson, NIST activities in support of space-based radiometric remote sensing, Proceedings of the SPIE - The International Society for Optical Engineering, 4450, 2001. • Tsai, B. K., and B. C. Johnson, Evaluation of uncertainties in fundamental radiometric measurements, Metrologia, 35(4), 587-593, 1998. Step 1: Start with Calibration Equation Dykema et al.: CLARREO Radiometric Concept and ...

49. Calibration equation includes complex phase (Revercomb et al. 1988) information: The measured signal is a vector sum of the two input ports plus beamsplitter emission: The input radiance includes scene radiance plus self-emission from the optics: These equations allow for completely general phase relationships appropriate to an absorbing, single-layered beamsplitter (Weddigen, Thériault). Dykema et al.: CLARREO Radiometric Concept and ...

50. Stray light effects cannot be ignored: Nor can polarization effects: Note that nonlinearity aliases spectral information and is best expressed in the interfogram (temporal) domain: Dykema et al.: CLARREO Radiometric Concept and ...