Global 20+ Site Validation System (G20)
Although VIIRS has onboard calibration for all channels, it is important that the calibrated SDR are independently validated. A major effort towards this end is the development of the world-wide validation site radiometric time series. The goal is to construct the time series for the entire period of the mission over about 20 vicarious sites to monitor the stability of the VIIRS calibration. Many of these sites are endorsed by the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration/Validation (WGCV). Legacy sites such as MOBY are also included. The time series has already been used for diagnoses for the recent H and F factor trend changes. In addition to the ground based sites, the time series also includes the Deep Convective Cloud time series, and the Lunar Band Ratio Time Series.