Landsat-7 ETM+ Radiometry
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9:00-9:45 AM Tuesday, 28 November 2006 Landsat Calibration Working Group (LCWG) Meeting PowerPoint PPT Presentation


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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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9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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, [email protected], 301-614-6610

LPSO:Land Cover Satellite Project Science Office, NASA/GSFC/614.4 Greenbelt, MD 20771 USA

and

David Landis

SSAI, [email protected], 301-614-6605

LPSO:Land Cover Satellite Project Science Office, NASA/GSFC/614.4 Greenbelt, MD 20771 USA

Jeff Miller

RSIS, [email protected], 301-614-6611

Instrumentation Science Branch, NASA/GSFC/614.6 Greenbelt, MD 20771 USA

Jennifer Sun

SSAI, [email protected], 301-614-6618

LPSO:Land Cover Satellite Project Science Office, NASA/GSFC/614.4 Greenbelt, MD 20771 USA

John Barker:

1)

2)


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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)


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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


9 00 9 45 am tuesday 28 november 2006 landsat calibration working group lcwg meeting

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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