In-flight absolute calibration of the CCD/CBERS-2 sensor data

The success of any remote sensing program is directly related to the knowledge of both spectral and radiometric characteristics of the sensors involved. The Brazilian remote sensing user’s community has explored the relationship between orbital radiometric data and biophysical data since the beginning of the nineties using the Thematic Mapper (TM) sensor as the main source of data. Since the first images of the sensors onboard CBERS-2 were made available by INPE, users have asked information about the conversion of image digital numbers to physical data as radiance or reflectance. This paper describes the main steps that were carried out to calculate the in-flight absolute calibration coefficients for CCD images at level 2 (radiometric and geometrical corrections included) considering the reflectancebased method. It was also included some remarks about the preliminary evaluation of these coefficients application from a user point of view.