NPL provides calibration services and support for “ground-based” measurements, including the calibration of sources and detectors. The following is an example of our capability for support for vicarious calibration.

GRASS being used during the NCAVEO Field Experiment

In June 2006 the Network for the Calibration and Validation of Earth Observation data (NCAVEO), organised a field experiment that took place at Chilbolton, Hampshire. The Optical Technologies team joined 54 other people, 4 aircraft, and 5 satellites to validate and intercompare data from a range of airborne and satellite sensors. The Gonio Radiometric Spectrometer System (GRASS) instrument was first deployed during the experiment, and although not completely built, performed very well.

All the reflectances panels were calibrated and traceable to NPL's primary standards.

Additional, all of the field instruments used during the field experiment were calibrated against an NPL standard, a Transfer Standard Absolute Radiance Source (TSARS).