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9:00-9:45 AM Tuesday, 28 November 2006 Landsat Calibration Working Group (LCWG) Meeting

Landsat-7 ETM+ Radiometry Instrument-Based Stability/Calibration for Level-OR Characterization & Correction. The Art and Precision of ETM+ Radiometry Requirements for and Approach to Characterizing ETM+ Radiometry.

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9:00-9:45 AM Tuesday, 28 November 2006 Landsat Calibration Working Group (LCWG) Meeting

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  1. Landsat-7 ETM+ Radiometry Instrument-Based Stability/Calibrationfor Level-OR Characterization & Correction The Art and Precision of ETM+ Radiometry Requirements for and Approach to Characterizing ETM+ Radiometry 9:00-9:45 AM Tuesday, 28 November 2006 Landsat Calibration Working Group (LCWG) Meeting At NASA Goddard Space Flight Center (GSFC, Bldg 33, Rm A128) Greenbelt, MD 20771 USA by John L. Barker, Ph. D. Landsat Associate Project Scientist, John.L.Barker@nasa.gov, 301-614-6610 LPSO:Land Cover Satellite Project Science Office, NASA/GSFC/614.4 Greenbelt, MD 20771 USA and David Landis SSAI, David.R.Landis.1@gsfc.nasa.gov, 301-614-6605 LPSO:Land Cover Satellite Project Science Office, NASA/GSFC/614.4 Greenbelt, MD 20771 USA Jeff Miller RSIS, Jeffrey.A.Miller.1@gsfc.nasa.gov, 301-614-6611 Instrumentation Science Branch, NASA/GSFC/614.6 Greenbelt, MD 20771 USA Jennifer Sun SSAI, Jennifer.B.Sun@gsfc.nasa.gov, 301-614-6618 LPSO:Land Cover Satellite Project Science Office, NASA/GSFC/614.4 Greenbelt, MD 20771 USA John Barker: 1) 2)

  2. Workshop Objectives The Art and Precision of ETM+ Radiometry The primary objective of this workshop is to provide a technical overview for transferring the radiometric research effort on improved algorithms for characterizing Landsat-7 ETM+ radiometry to Professor Dennis Helder at South Dakota State University (SDSU). This work has been done by NASA’s Landsat Project Science Office (LPSO) at Goddard Space Flight Center (GSFC) under the supervision of Dr. John Barker, who is retiring on January 3, 2007. It is anticipated that version 1.0 software will be passed from GSFC to SDSU during December, 2006. John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  3. Thanks for Multi-Year SupportLamp-Based ETM+ Radiometry NASA support for LPSO Analysis, modeling & algorithm development Landsat Project Scientist Recognizing need for team & continuity USGS EDC Image Assessment System (IAS) Creating , filling and maintaining the Landsat-7 IAS Oricle Database Mission Operation Center (MOC) Delta-I imaging collects & on-line telemetry access Contract personnel Jennifer Sun, Jeff Miller and Dave Landis John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  4. Agenda of Workshop on The Art and Precision ofLandsat-7 ETM+ Radiometry • 9:00 1. Approach to On-Board Characterization of ETM+ • 10:00 2. Landsat-7 ETM+ MOC and PCD Telemetry • 11:00 3. IAS-Based IC Lamp Characterization • 12:00 Lunch • 13:30 4. Path-Processing (PP) of ETM+ Background • 14:30 5. PP-Based IC Lamp Characterization John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  5. Overview of Talk 1. On-Board Calibration MethodsThe Art & Precision of ETM+ Radiometry Stability, precision and accuracy Radiometric requirements for satellite remote sensing of changes on the Earth’s surface Current reflective band knowledge of ETM+ radiometry “Invariant” Desert Sites (±2% single site precision) Ground Observations (±3-5% absolute accuracy) Between-Sensor Cross-Calibration (±5% relative) On-Board Calibrators (±0.1% uncertainty in trends) Why instrument-based lamp & solar panel calibration? Scene & path-processing instrument-based approaches John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  6. Outline LPSO Radiometric Talks Review lamp-2 IC IAS scene-based results Justification for studying on-board calibrators Review lamp-1 IC IAS scene-based results Temperature Sensitivity Current Sensitivity Temperature Normalization Current Equilibration Current Normalization Review lamp-1 and lamp-2 path processing results John Barker: 1) Tim and Emily and Dennis, 9:35 2)

  7. Lamp-Based ETM+ RadiometryWhy Instrument-Based Lamps? Temperature-Correction (within-band) up to 0.3 % Current-Equilibration (within-band) up to 2 % Current-Normalization (within-band) -1 to +7 % IC Between-Bands Normalization up to 6 % John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  8. Lamp-Based ETM+ RadiometryWhy Instrument-Based Calibration? During launch and over the on-orbit life-time of the instrument, detector sensitivities, which are necessary for calibrating the sensor imagery, will change from pre-launch measurements due to factors such as: vibration, contamination and degradation of the optics, as well as changes in filter, detector and electronics characteristics. Therefore, imagers must be re-calibrated on orbit. On-orbit cross-calibration to other sensors and to ground observations are limited to absolute band-average accuracies of ± 1-5 % every month or so. On-board lamp calibrators are capable of detector-specific precision of ± 0.1 % during any acquisition. John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  9. StrengthsLamp-Based ETM+ Radiometry Lamps monitor every scan (0.072 seconds/scan) only way to characterize radiometric stability within orbit primary monitor for times less than a month Smoothly varying trends of equilibrated IC pulses are potentially correctable for systematic errors Trending precision possible to better than ± 0.1 % John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  10. Limitations & AmeliorationsLamp-Based ETM+ Radiometry Lamps need to equilibrate (use only equilibrated data) Lamp filaments degrade (source of most of IC change) limit degradation by limiting use (Lamp-2) normalize for: 1) lamp current, 2) temperature (IC vs Detectors), 3) point discontinuities, 4) lamp flares (between-band constancy) and 5) vacuum and/or zero-g on-orbit changes cross-calibrate normalized lamps Does not monitor fore-optics of ETM+ compare trends in sensitivity to solar panel John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  11. Conclusions (1 of 2)Lamp-Based ETM+ Radiometry Lamps equilibrate to 0.1 % within ten minutes Lamp-2 current is constant over mission lifetime Lamp-2 trends less than any other calibrator Lamp-1 shows linear current sensitivity, Observed change in lamp current correctable Lamp-1 shows linear temperature sensitivity John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  12. Conclusions (2 of 2)Lamp-Based ETM+ Radiometry DC Restore (DCR) noise spikes in current IAS background Shutter backgrounds have sensitivities and trends Standard Deviations of IAS Backgrounds show outliers Forward scan pulses are moving into image Forward and reverse scan pulses are nearly the same Low to high gain conversions have an offset also not exactly 1.5000x slope (gain) factor IC and FASC both show B5 & B7 on-orbit equilibration John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  13. Operational RecommendationsBased on IC Reference Detectors Populate IAS Database with Separate forward and reverse scan IC pulses Populate IAS Database with daily scene-based collects 50 % random 50 % (at on-time = 10 minutes, and max on-time) John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  14. Research Recommendations Lamp-Based ETM+ RadiometryShutter Background (1 of 2) Aggregate along-track within-scan background spectra and their variability in order to select background collect windows on the shutter that are constant. Recommend new background collect windows for IAS to avoid DC Restore (DCR) on/off spikes Develop linear gain conversion equations for calibration parameter file (CPF) with detector-specific offsets Test H0: slope identical for each A/D converter Test for time-dependence of offset and gain John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  15. Research Recommendations Lamp-Based ETM+ RadiometryShutter Background (2 of 2) Develop filters & corrections for backgrounds so that scan values can be replaced with averages for the purpose of developing a path-processing alternative to current scene-based background (bkgd) characterization. Cross-validate path-processing with scene-based bkgd John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  16. Research Recommendations Lamp-Based ETM+ RadiometryIC Processing Algorithms (1 of 2) Characterize, normalize and cross-calibrate lamps for 1) lamp current, 2) temperature (IC vs Detectors), use smoothed multi-date path-processing fits vs of t_on>10’ for MOC temperatues and IC for multiple linear regression of temperature sensitivity. 3) point discontinuities, 4) lamp flares (between-band constancy) and 5) vacuum and/or zero-g on-orbit changes, after other dependencies have been normalized out. John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  17. Research Recommendations Lamp-Based ETM+ RadiometryIC Processing Algorithms (2 of 2) Develop minor-frame “super-spectra” (SS) IC integration Compare & select between P2, P4 and SS IC integration Develop within-band models for IC normalization to account changes in IC radiance patterns Develop between-band models for IC normalization to account for changes in IC optics and lamps Develop path-processing alternative to current scene-based radiometric characterization. John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  18. Research Recommendations Lamp-Based ETM+ RadiometryOther Phenomena Quantify early on-orbit B5 and B7 equilibrations for re-calibration of archived imagery Quantify time-dependence of FWD, REV and AVE IC Cross-validate fitted MOC and PCD telemetry recommend IAS use of MOC telemetry Cross-validate path-processing with scene-based IC Cross-validate path-processing with scene-based FASC Characterize possible reflective band memory effects using before, during and after DCR backgrounds for both forward and reverse scans with FASC collects John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  19. Lamp-Based Radiometry Future Imagers Yes, lamps are potentially usable on future missions Pre-select lamps for stability during burn-in Design needs as much of optics as possible; ideally all Provide selectable on/off constant-radiance mode Include temperature, voltage and current monitors Pre-launch multi-year in-vac testing of lamp & IC optics current, voltage, resistance & T dependences spectral “graying” for between-band use Design sensitivity tests for on-orbit use for corrections Provide dynamic range for testing lamps together Use at least 4 lamps for logarithmically different use John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  20. LPSO Calibration Research Lessons Learned Transparency is needed at all levels of management There is no substitute for transparency at all levels in the government and with contractors when addressing technical problems. Continuity of funding of scientific personnel is essential Only the scientific users can be counted on to maintain the multi-decade expertize and interest in designing, characterizing and calibrating current and future satellite remote sensing imagers because of their inherent need for and understanding of calibrated imagery for monitoring the Earth. John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

  21. Agenda of Workshop on The Art and Precision ofLandsat-7 ETM+ Radiometry • 9:00 1. Approach to On-Board Characterization of ETM+ • 10:00 2. Landsat-7 ETM+ MOC and PCD Telemetry • 11:00 3. IAS-Based IC Lamp Characterization • 12:00 Lunch • 13:30 4. Path-Processing (PP) of ETM+ Background • 14:30 5. PP-Based IC Lamp Characterization John Barker: 1) IC trend is relatively linear/stable after 2.6 y, after 4.2y 2) Principle components, graying of all bands, internal IC optics ( Dichroics or ND filters) needs to be done to agree to Lamp-2 3_need sensitivity curves on orbit

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