THE MISR CALIBRATION PROGRAM

The Multiangle Imaging SpectroRadiometer (MISR) is currently under dev elopment for NASA's Earth Observing System. The instrument consists of nine pushbroom cameras, each with four spectral bands in the visible and near-infrared. The cameras point in different view directions to p rovide measurements from nadir to highly oblique view angles in the al ong-track plane. Multiple view-angle observations provide a unique res ource for studies of clouds, aerosols, and the surface. MISR is built to challenging radiometric and geometric performance specifications. R adiometric accuracy, for example, must be within +/-3%/1 sigma, and po larization insensitivity must be better than +/-1%. An onboard calibra tor (OBC) provides monthly updates to the instrument gain coefficients . Spectralon diffuse panels are used within the OBC to provide a unifo rm target for the cameras to view. The absolute radiometric scale is e stablished both preflight and in orbit through the use of detector sta ndards. During the mission, ground data processing to accomplish radio metric calibration, geometric rectification and registration of the ni ne view-angle imagery, and geophysical retrievals will proceed in an a utomated fashion. A global dataset is produced every 9 days. This pape r details the preflight characterization of the MISR instrument, the d esign of the OBC, and the radiance product processing.