SeaWiFS transfer-to-orbit experiment

We present the results of an experiment designed to measure the changes in the radiometric calibration of the Sea-viewing Wide Field-of-view Sensor (S eaWiFS) from the time of its manufacture to the time of the start of on-orb it operations. The experiment uses measurements of the Sun at the manufactu rer's facility to predict the instrument outputs during solar measurements immediately after launch. Because an onboard diffuser plate is required for these measurements, the experiment measures changes in the instrument-diff user system. There is no mechanism in this experiment to separate changes i n the diffuser from changes in the instrument. For the eight SeaWiFS bands, the initial instrument outputs on orbit averaged 0.8% higher than predicte d with a standard deviation of 0.9%. The greatest difference was 2.1% (actu al output higher than predicted) for band 3. The estimated uncertainty for the experiment is 3%. Thus the transfer-to-orbit experiment shows no change s in the radiometric sensitivities of the SeaWiFS bands-at the 3% level-fro m the completion of the instrument's manufacture to its insertion into orbi t.