HR: 16:40h
AN: A54D-04    [Abstracts]
TI: Experimental and Metrological Basis for SI-Traceable Infrared Radiance Measurements From Space
AU: * Gero, P J
EM: gero@huarp.harvard.edu
AF: Harvard School of Engineering and Applied Sciences, 12 Oxford St., Cambridge, MA 02138, United States
AU: Dykema, J A
EM: dykema@fas.harvard.edu
AF: Harvard School of Engineering and Applied Sciences, 12 Oxford St., Cambridge, MA 02138, United States
AU: Anderson, J G
EM: anderson@huarp.harvard.edu
AF: Harvard School of Engineering and Applied Sciences, 12 Oxford St., Cambridge, MA 02138, United States
AU: Leroy, S S
EM: leroy@huarp.harvard.edu
AF: Harvard School of Engineering and Applied Sciences, 12 Oxford St., Cambridge, MA 02138, United States
AB: In order to establish a climate benchmark record and to be useful in interdecadal climate forecast testing, satellite measurements of high spectral resolution infrared radiance must have uncertainty estimates that can be proven beyond a doubt. An uncertainty in radiance of about 1 part in 1000 is required for climate applications. This can be accomplished by appealing to the best measurement practices of the metrology community. The International System of Units (SI) are linked to fundamental physical properties of matter, and can be realized anywhere in the world without bias. By doing so, one can make an accurate observation to within a specified uncertainty. Achieving SI-traceable radiance measurements from space is a novel requirement, and requires specialized sensor design and a disciplined experimental approach. Infrared remote sensing satellite instruments typically employ blackbody calibration targets, which are tied to the SI through Planck's law and the definition of the Kelvin. The blackbody temperature and emissivity, however, must be determined accurately on- orbit, in order for the blackbody emission scale to be SI-traceable. We outline a methodology of instrument design, pre-flight calibration and on-orbit diagnostics for realizing SI- traceable infrared radiance measurements. This instrument is intended as a component of the Climate Absolute Radiance and Refractivity Earth Observatory (CLARREO), a high priority recommendation of the National Research Council decadal survey. Calibration blackbodies for remote sensing differ from a perfect Planckian blackbody; thus the component uncertainties must be evaluated in order to confer traceability. We have performed traceability experiments in the laboratory to verify blackbody temperature, emissivity and the end-to-end radiance scale. We discuss the design of the Harvard standard blackbody and an intercomparison campaign that will be conducted with the GIFTS blackbody (University of Wisconsin, Madison) and radiometric calibration facilities at NIST. The GIFTS blackbody is a high-performance space-qualified design with a new generation of on-orbit thermometer calibration via miniaturized fixed point cells. NIST facilities allow the step-by-step measurement of blackbody surface properties, thermal properties, on-axis emissivity, and end-to-end radiometric performance. These activities will lay the experimental groundwork for achieving SI-traceable infrared radiance measurements on a satellite instrument.
DE: 1610 Atmosphere (0315, 0325)
DE: 1640 Remote sensing (1855)
DE: 1694 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting