The University of Wisconsin Space Science and Engineering Center Absolute Radiance Interferometer (ARI): instrument overview and radiometric performance

Spectrally resolved infrared (IR) and far infrared (FIR) radiances measured from orbit with extremely high absolute accuracy (< 0.1 K, k = 3, brightness temperature at scene temperature) constitute a critical observation for future climate benchmark missions. The challenge in the IR/FIR Fourier Transform Spectrometer (FTS) sensor development for a climate benchmark measurement mission is to achieve the required ultra-high accuracy with a design that can be flight qualified, has long design life, and is reasonably small, simple, and affordable. In this area, our approach is to make use of components with strong spaceflight heritage (direct analogs with high TRL) combined into a functional package for detailed performance testing. The required simplicity is achievable due to the large differences in the sampling and noise requirements for the benchmark climate measurement from those of the typical remote sensing infrared sounders for weather research or operations. A summary of the instrument design and development, and the radiometric performance of the Absolute Radiance Interferometer (ARI) at the University of Wisconsin Space Science and Engineering Center (UW-SSEC) will be presented.