We present a method to characterize the emissivity of a spaceborne blackbody and the instrument line-shape (ILS) of a
spectrometer using a quantum cascade laser (QCL) based reflectometer. QCLs allow the realization of on-orbit
reflectometry that directly observes blackbody surface properties. We present experimental data verifying that the QCL
reflected radiance signal can be measured by an Earth-observing spectrometer. The QCL can also be used to realize a
monochromatic, spatially uniform source of infrared radiation to measure the spectrometer's ILS, which can be inverted
to obtain diagnostic information about the integrity of the detector and nonlinearities in the detector signal-chain.
The scientific objectives of the CLimate Absolute Radiance and REfractivity Observatory
(CLARREO) new start recommended by the National Research Council Decadal Survey
prioritize high accuracy measurements of infrared spectra, tested for systematic error, tied
to international measurements standards, and suitable for testing long-term climate
forecasts (of 10 years or more). We present the results from a realistic proof-of-concept
study for this mission concept and examine the prospects of testing and improving long-term
climate forecasts from ensembles of coupled General Circulation Models (GCMs)
such as those participating in the Intergovernmental Panel on Climate Change 4th
Assessment Report (IPCC-4AR).
Incontrovertible evidence of climate change and the underlying causes is necessary to inform public debate and to guide
policy and economic decisions. To affect key societal decisions, this evidence must be obtained from measurements that
are irrefutably tied to recognized international measurement standards. The International System of Units (SI) provides
the appropriate measurement foundation for this application. The feasibility of achieving this objective and the resulting
benefits to long-term climate forecasting are presented. The significant differences between realizing SI-traceability for
space-based measurements and for laboratory measurements are detailed. An overview is presented of technological
innovations in calibration standards and evolution in measurement approaches that define these new infrared standards.
These include calibration blackbodies with built-in temperature standards and redundant sensors that admit new
diagnostic tests of measurement uncertainty. An approach to rapid deployment is discussed, along with its resulting data
product and benefits for long-term climate forecasting.