On-orbit absolute calibration of temperature with application to the CLARREO mission

Best, Fred A.; Adler, Douglas P.; Ellington, Scott D.; Thielman, Donald J.; Revercomb, Henry E.

doi:10.1117/12.795457

Cited by 22 publications

(25 citation statements)

References 11 publications

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“…Figure 2a demonstrates how this is achieved for the thermal infrared interferometer, including independent deep cavity blackbodies with multiple phase change cells for temperature accuracy; an infrared quantum cascade laser to monitor blackbody emissivity as well as spectral response; multiple deep space views to verify polarization sensitivity; and a heated halo on the blackbody to independently verify blackbody emissivity (Anderson et al 2004;Dykema and Anderson 2006;Gero et al 2008Gero et al , 2012Best et al 2008). Figure 2b demonstrates the approach for the refl ected solar spectrometer and its use of the moon as a reference for stability in orbit, the sun with multiple attenuators to verify instrument nonlinearity of gain across the Earth viewing dynamic range, and the ability to directly scan deep space to verify instrument offsets (Espejo et al 2011;Fox et al 2011).…”

Section: Mission and Instrument Designmentioning

confidence: 99%

Achieving Climate Change Absolute Accuracy in Orbit

Wielicki

Young

Mlynczak

et al. 2013

Bulletin of the American Meteorological Society

257

210

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The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5–50 μm), the spectrum of solar radiation reflected by the Earth and its atmosphere (320–2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a “NIST [National Institute of Standards and Technology] in orbit.” CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations

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Section: Mission and Instrument Designmentioning

confidence: 99%

Achieving Climate Change Absolute Accuracy in Orbit

Wielicki

Young

Mlynczak

et al. 2013

Bulletin of the American Meteorological Society

257

210

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“…The concept for using miniature phase transition cells to calibrate imbedded blackbody cavity thermistors is illustrated in Figure 3, which shows a typical transient temperature response (signature) from one of the blackbody cavity thermistors during a gallium (<1 gram) melt event. 10,11 At the start of the melt process the blackbody cavity is brought to thermal stability in the constant temperature mode about 50 mK under the expected phase change temperature. Then the blackbody controller is switched into constant power mode using a power level that would bring the cavity to about 100 mK above the expected phase change temperature.…”

Section: Key Features Of the Oars And Phase Transition Cell Operationmentioning

confidence: 99%

Results from recent vacuum testing of an on-orbit absolute radiance standard (OARS) intended for the next generation of infrared remote sensing instruments

et al. 2014

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Future NASA infrared remote sensing missions will require better absolute measurement accuracies than now available, and will most certainly rely on the emerging capability to fly SI traceable standards that provide irrefutable absolute measurement accuracy. To establish a CLARRREO-type climate benchmark, instrumentation will need to measure spectrally resolved infrared radiances with an absolute brightness temperature error of better than 0.1 K, verified onorbit. This will require an independent high-emissivity (>0.999) verification blackbody with an emissivity uncertainty of better than 0.06%, an absolute temperature uncertainty of better than 0.045K (3 sigma), and the capability of operation over a wide range of (Earth scene) temperatures. Key elements of an On-Orbit Absolute Radiance Standard (OARS) meeting these stringent requirements have been demonstrated in the laboratory at the University of Wisconsin and have undergone further refinement under funding from NASA's Earth Science and Technology Office, culminating in an endto-end demonstration under vacuum with a prototype climate benchmark instrument. We present the new technologies that underlie the OARS, and the results of testing that demonstrate the required accuracy is being met in a vacuum environment. The underlying technologies include: on-orbit absolute temperature calibration using the transient melt signatures of small quantities (<1g) of reference materials (gallium, water, and mercury) imbedded in the blackbody cavity; and on-orbit cavity spectral emissivity measurement using a carefully baffled heated halo placed in front of the OARS blackbody viewed by the infrared spectrometer system. Emissivity is calculated from the radiance measured from the blackbody combined with the knowledge of key temperatures and radiometric view factors.

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“…The OARS uses transient temperature melt signatures from three (or more) different phase change materials to provide absolute calibration for the blackbody thermistor sensors covering a wide, continuous range of temperatures [7][8][9]. The system uses very small masses of phase change material (<1 g), making it well suited for spaceflight application.…”

Section: The Absolute Radiance Interferometer (Ari)mentioning

confidence: 99%

“…The OARS is a source that will be used to maintain SI traceability of the radiance spectra measured by the calibrated interferometer sensor [7][8][9]; (2) On-orbit Cavity Emissivity Modules (OCEMs), providing a source (quantum cascade laser (QCL) or "Heated Halo") to measure any change in the cavity emissivity of the OARS and calibration reference sources [10][11][12][13];…”

Section: The Absolute Radiance Interferometer (Ari)mentioning

confidence: 99%