A1260098114XEYQq

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Measurement Science for Climate Dr. Katharine
Gebbie, Director Physics Laboratory National
Institute of Standards and Technology http//physi
cs.nist.gov/
ASIC3 Workshop Achieving Satellite Instrument
Calibration for Climate Change 16-18 May 2006
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The 1st Workshop Articulated Challenging
Measurement Requirements for Climate.
Examples
Variable Accuracy Stability (Decadal)
TOA Incoming Solar Irradiance 1 W m-2 0.3 W m-2
TOA Outgoing Long-wave Radiance 1 W m-2 0.2 W m-2
Surface Albedo 0.01 0.002
Sea-Surface Temperature 0.1 K 0.04
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Requirements are still not being met!
Example Total Solar Irradiance
Total Solar Irradiance W/m2
Year
Target Precision 0.3 W m-2
Target Accuracy 1 W m-2
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Meeting the Requirements
Adherence to Global Climate Observing System
(GCOS) Ten Climate Monitoring Principles
...

1. Rigorous pre-launch calibration
2. Adequate on-board calibration

...
Endorsed by the National Research Council
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New Satellite Program Policies are Increasing the
Importance of Pre-Launch Calibration

• Weather satellites will be required to provide
  climate quality data.
• Satellites will only be replaced upon failure.
• Budgets will limit expensive field validation
  measurements.

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Calibrations/Measurements Must be Tied to
National and International Standards
Observing and Monitoring System Goal 3 Provide
Stewardship of the Observing System   Objective
3.1. Follow climate monitoring principles.
Instrument calibration, characterization, and
stability become paramount considerations.
Instruments must be tied to national and
international standards such as those provided by
the National Institute of Standards and
Technology (NIST)...
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Standards Should be SI Traceable
that those responsible for studies of Earth
resources, the environment and related issues
ensure that measurements made within their
programs are in terms of well-characterized SI
units so that they are reliable in the long term,
be comparable world-wide and be linked to other
areas of science and technology through the
worlds measurement system established and
maintained under the Convention of the Meter.
Resolution adopted by the 20th Conference
Generale des Poids et Measures (1995)
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The Success of GEOSS Depends Upon SI Traceability
Global Earth Observation System of
Systems Requires that instruments be
interoperable and measurements be comparable
across nations, places, and time.
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WMO-CIPM Partnership to Facilitate SI Traceability
World Meteorological Organization (WMO)
International Committee for Weights and Measures
(CIPM)
...have agreed to work together to ensure that
data related in particular to measurements of
state and composition of atmosphere and water
resources, coming from the programmes organized
under the auspices of the WMO, are properly based
on units traceable to the SI through the
procedures of the CIPM MRA and the Technical
Regulations of the WMO.
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NISTs Radiometric Measurements are Traceable to
the SI Watt through the Cryogenic Radiometer...
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...and Validated Through International
Comparisons
Comparison of Spectral Irradiance Scale
Uncertainties

• Lowest uncertainties in the world
• Many NMIs use NIST irradiance standards,
  including Singapore, S. Korea, New Zealand,
  Poland, Austria, Sweden, Hungary, Canada, Mexico,
  Netherlands, South Africa

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The Value of Intercomparisons Recognized by the
Climate Community
From the Climate Change Science Program Strategic
Plan Experience from previous scientific
assessments, the NIST, and other national
standards laboratories have shown that actual
accuracy is only known after comparison of
independent measurements and analysis from
multiple laboratories...
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The National Metrology Intercomparison Model
Suggests an Additional Monitoring Principle
Independent methods of observations and analysis
of data are required
Bruce Wielicki, NASA
Use of multiple observing systems and multiple
analysis teams (for the same variable)
Tom Karl, NOAA
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Agencies Partner with NIST to Help Meet
Measurement/Traceability Requirements

• NASA
• NOAA
• USGS
• EPA
• USDA
• DoD
• DoE

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NIST is Working to Improve Climate Measurements

• Strengthened strategic partnership with NOAA
• New MOU with Space Dynamics Laboratory
• New optical radiation sources and detectors

POWR
LED Sources
SIRCUS
SURF
Absolute Radiometers
HIP
FASCAL2
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NIST Response to Recommendations of the Previous
Workshop - Calibration Support for CrIS

Recommendation Calibrate laboratory blackbody
target radiances using NIST Portable Calibrated
Radiometer (TXR)

• Response The NPP/NPOESS Cross-track Infrared
  Sounder (CrIS) blackbody will be characterized at
  the NIST Medium Background Infrared (MBIR)
  Facility.
• Preparations are in progress
• CrIS ECT blackbody testing planned in FY07.
• CrIS ICT blackbody testing planned in FY08

TXR in the MBIR Chamber
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NIST Response to Recommendations of the Previous
Workshop Multiple Calibration References

Recommendation Implement multiple calibration
referenceslunar measurements, calibration lamps,
and solar diffusersfor monitoring the in-orbit
stability of VIS radiometers.
Response See Session 4 talk, Refinement of Moon
as Transfer Standard for Climate Change, by
Steven Lorentz
Lunar Spectral Irradiance (LUSI) Telescope
Concept
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NIST Response to Recommendations of the Previous
Workshop Spectral Sources

Recommendation Enhance NIST spectral sources and
transfer radiometers to cover the full reflected
solar and emitted thermal IR spectra of the earth.
Response Development of Hyperspectral Image
Projectors (HIPs) based on micromirror arrays
Recombine the Light
Dispersing element
Spatial Light Modulator (SLM)
Light Guide
SLM
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NISTs Commitment to Climate Measurement Science
NIST is committed to providing the measurement
science for ensuring the accuracy of climate
measurements critical for sound policy
decisions.
Dr. William Jeffrey NIST Director