1. The MIAMI-2001 Radiometer Intercomparison Peter J. Minnett Rosenstiel School of Marine and Atmospheric Science, University of Miami, Florida, USA Ian J. Barton CSIRO Marine Labs Hobart, Australia Joe P. Rice Optical Technology Division National Institute of Standards and Technology Gaithersburg, Maryland, USA ENVISAT Validation Workshop Frascati, Italy 12 December 2002

2. Overview Objectives Radiometers Laboratory results Shipboard results Conclusions

3. Miami-2001Radiometer Intercalibration Workshop. To calibrate and compare infrared radiometers used in the validation of the different surface temperature products derived from earth observation satellites. These aims included an assessment of the relative performance of each instrument as well as ensuring that surface measurements used in satellite product validation are traceable to SI standard units.

4. Participants Dr. Ali AbtahiNASA Jet Propulsion Laboratory, Pasadena, CA, USA Dr. Ian BartonCSIRO Marine Research, Hobart, Australia Dr. Jim ButlerNASA GSFC, Greenbelt, MD, USA Dr. Craig DonlonEEC Joint Research Centre, Ispra, Italy Dr. Marianne EdwardsLeicester University, UK Ms. Ruth FogelbergApplied Physics Laboratory, U. Washington, Seattle, WA,USA Ms. Jenny HanafinRSMAS-MPO, University of Miami, FL, USA Dr. Simon Hook NASA Jet Propulsion Laboratory, Pasadena, Ca., USA Dr. Andy Jessup Applied Physics Laboratory, U. Washington, Seattle, WA, USA Dr. Carol JohnsonNIST, Gaithersburg, MD, USA Ms. Erica KeyRSMAS-MPO, University of Miami, FL, USA Ms. Trina LichtendorfApplied Physics Laboratory, U. Washington, Seattle, WA, USA Mr. Kevin MailletRSMAS-MPO, University of Miami, FL, USA Dr. Peter MinnettRSMAS-MPO, University of Miami, FL, USA Dr. Tim NightingaleRutherford Appleton Laboratory, Chilton, UK. Dr. Mike ReynoldsBrookhaven National Laboratory, USA Dr. Joe RiceNIST, Gaithersburg, MD,USA Dr. Goshka SzczodrakRSMAS-MPO, University of Miami, FL, USA Dr. Brian WardNOAA, AOML, Miami, FL, USA Dr. Gary WickNOAA, ETL, Boulder, CO., USA

5. Instruments Infrared radiometers that participated in the campaign InstrumentInstitutionLab.SeaP.I. EOS TXR (Transfer radiometer)NIST, USAYesNoJ. Rice M-AERIRSMAS, U. Miami.NoYesP. Minnett SISTeRRAL,UK.Yes T. Nightingale DAR011CSIRO, Australia.Yes I. Barton CIRIMSAPL, U. Washington.NoYesA. Jessup ISAR-5JRC, EEC.Yes C. Donlon Nulling radiometersNASA JPLYes S. Hook Tasco (off-the-shelf)CSIRO, AustraliaYes I. Barton Black bodies used for laboratory calibration. InstrumentInstitutionP.I. NIST-Certified & Designed Black Body TargetRSMAS, U. MiamiP. Minnett NIST Standard Black Body TargetNIST, USAC. Johnston CASOTS black bodyJRC, EECC. Donlon Hart Scientific Portable Black Body TargetAPL, U. WashingtonA. Jessup JPL Black Body CalibratorNASA-JPLS. Hook

6. Radiometers RadiometerFull name M-AERIMarine-Atmospheric Emitted Radiance Interferometer CIRIMSCalibrated InfraRed In situ Measurement System SISTeRScanning Infrared Sea Surface Temperature Radiometer ISAR-5Infrared SST Autonomous Radiometer -5 DAR011CSIRO Division of Atmospheric Research 011 JPLJet Propulsion Laboratory Near-Nulling Radiometer Tasco“Lunchbox”

7. Radiometer Characteristics RadiometerPass-band µm DetectorsBlack-bodiesSky correction Notes M-AERI3-18HgCdTe – In Sb Cooled to 78K Two large cavities – SSEC design Scan mirrorSST derived at 7.7µm CIRIMS9.6 - 11.5Heitronics KT-11.85* Hart Scientific mini- water bath black body Dedicated radiometer Mismatch of pass- bands of two radiometers during the workshop SISTeR10.8PyroelectricTwo small cavities.Scan mirror ISAR9.6-11.5Heitronics KT-11.85D * # Two small cavitiesScan mirror DAR01110.5-11.5PyroelectricTwo small cavitiesScan mirrorSky view in opposite quadrant JPL7.8 -13.6ThermopileOne cavity, actively controlled ModelledUses ‘nulling’ of signal to internal black body Tasco?? ExternalNoneHand-held *The Heitronics uses a chopped pyroelectric detector. # The ISAR Heitronics is modified to allow the measurement of temperatures down to –100 o C.

8. Objectives of laboratory measurements To characterize all black-body calibration targets by NIST EOS TXR, leading to an estimate of emissivity of black body cavities as a function of temperature, wavelength (5 and 10µm) and, aperture.

9. The NIST EOS TXR See:Rice, J. P. and B. C. Johnson, 1998. The NIST EOS Thermal- Infrared Transfer Radiometer., Metrologia, 35, 505-509 EOS Standard Cryogenic detectors (liquid N 2 ) λ= 5 & 10µm

10. NIST water-bath black-body calibration target See: Fowler, J. B., 1995. A third generation water bath based blackbody source., J. Res. Natl.Inst. Stand. Technol., 100, 591-599

11. CASOTS black-body calibrator See: Donlon, C. J., T. Nightingale, L. Fiedler, G. Fisher, D. Baldwin and I. S. Robinson, 1999. The Calibration and Intercalibration of Sea-Going Infrared Radiometer Systems Using a Low Cost Blackbody Cavity, Journal of Atmospheric and Oceanic Technology, 16, 1183–1197

12. Temperature plateaus

13. Black-body calibrators

14. Black – body calibration errors

15. CSIRO DAR011 at the RSMAS WB-BB target

16. Radiometer calibration errors

17. And so to sea…….

18. On the R/V F.G. Walton-Smith

19. The SST radiometers

20. The radiometers

21. Cruise track

22. Time series of measurements

23. Results of at-sea comparisons

24. Miami-2001Radiometer Intercalibration Workshop. Following the radiometer calibration, intercomparison, and testing under field conditions, the international community has increased confidence in the results to be provided for validation of satellite-derived SSTs from the participating instruments. Radiometers work to ~0.1K uncertainty levels in the field Black body calibrators have been characterized with reference to NIST standard

25. Publications, in review Rice, J. P., J. J. Butler, B. C. Johnson, P. J. Minnett, K. A. Maillet, T. J. Nightingale, S. J. Hook, A. Abtahi, C. J. Donlon and I. J. Barton. The Miami2001 Infrared Radiometer Calibration and Intercomparison: 1. Laboratory Characterization of Blackbody Targets, Journal of Atmospheric and Oceanic Technology. Barton, I. J., P. J. Minnett, C. J. Donlon, S. J. Hook, A. T. Jessup, K. A. Maillet and T. J. Nightingale. The Miami2001 infrared radiometer calibration and inter-comparison: 2. Ship comparisons, Journal of Atmospheric and Oceanic Technology.

26. Acknowledgements Acknowledge funding from –NOAA-NESDIS –ESA –Eumetsat –Participant’s home institutes and funding agencies pminnett@rsmas.miami.edu