The recent interagency Achieving Satellite Calibration for Climate Change (ASIC-3) report highlighted the importance of benchmark measurements with highly accurate calibration for climate and weather applications. Similarly, the National Research Council (NRC) report entitled “Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond” addressed the need for new benchmark measurements, tied to international standards and tested for systematic errors on-orbit. The NRC Decadal Survey explicitly addressed the critical need for benchmark measurements in addressing societal objectives. The Executive Summary of the Decadal Survey delineated the CLimate Absolute Radiance and Refractivity Earth Observatory (CLARREO) mission, which includes a constellation of three small satellites flying benchmark infrared interferometers. CLARREO is designed to provide robust documentation of future climate suitable for quantifying human influence and test and improving climate models. The interferometers include novel technology to tie the instrument calibration to the International System of Units (SI) and test for systematic error on-orbit, and cover the far infrared (to at least 200 cm^{-1}) with a spectral resolution better than 1.0 cm^{-1}. This constellation provides measurements at six local times per day, providing very accurate sampling of the diurnal and semidiurnal cycles. Recent work shows that this constellation is capable of accurate intercalibration (to 0.1 K) of a weather sounder in sun-synchronous orbit on time periods of months using methods envisioned for the Global Space-based Inter-Calibration System (GSICS). In this way, the calibration of the future operational sounder network can be improved, while CLARREO can take advantage of the dense spatial sampling of the sounder network for a wide variety of process studies. The modest weight and power envelope of a CLARREO interferometer with its calibration hardware also allows its inclusion on a future sounder satellite as an option for improved sounder accuracy.