Spectral and Radiometric calibration of the Advanced Land Imager

Calibration of spectral and radiometric measurements of the Advanced Land Imager (ALI) is a critical element of its land-sensing mission. Without initial ground-based and subsequent on-orbit standardization, the data cannot be reliably used for the intricate analysis of atmospheric conditions and complex surface regions. Daily, weekly, and monthly recertification steps are taken to recalibrate the instrument for any spectral or radiometric fluctuations or drift. Ground calibration of the ALI occurred from September 1998 through January 1999 at Lincoln Laboratory [1–4]. In this article, we outline the techniques adopted during the ground-based spectral and radiometric calibration of the ALI and present results derived from subsystemand system-level measurements. Results from on-orbit calibration and testing are also presented and compared with the ground-based data.