ASSIST, Atmospheric Sounder Spectrometer for Infrared Spectral Technology: latest development and improvement in the atmospheric sounding technology

In July 2006, the Department of Energy (DOE) National Nuclear Security Administration (NNSA) initiated a new project in their remote sensing test and evaluation program. Upwelling and downwelling radiance ground truth measurements have been advanced as a result of this project. Upwelling radiance measurements are used for the spectral characterization of calibration targets, and downwelling measurements are used to profile the temperature and moisture within the atmospheric column above these targets. These measurements will be used for the development and improvement of atmosphere compensations algorithms, as well as for the evaluation of the radiometric accuracy of other remote sensing systems. In order to meet stringent wavelength and radiometric calibration requirements, the selected technology is based on a Michelson interferometer spectrometer equipped with an internal calibration unit. The proposed configuration facilitates precise radiometric accuracy for target measurements, as well as concurrent temperature and moisture profiling of the atmosphere's Planetary Boundary Layer (PBL) above the target. In this paper we describe the instrument approach and its configuration. We also present results demonstrating the instrument performance. Atmospheric sounding results are compared to measurements made with other sounding systems at the ARM site in Oklahoma.