Because of the unique viewpoint of Triana, all Earth orbiting satellites are in view throughout the day. In particular, the near-noon polar orbiting satellites TOMS, SeaWifs, MODIS, and AVHRR will view the same scenes whenever Triana is obtaining global data from sunrise to sunset. Since the EPIC wavelength channels were selected to match closely with TOMS in the UV and with MODIS in the visible, the data products will be very similar and can be directly compared. These comparisons will validate both the calibration and data reduction algorithms. Other near-noon observing satellite instruments have similar wavelength channels and data products that can also be included in validation studies (e.g., SeaWifs, AVHRR, and CERES). In addition to validation, the greater temporal coverage of EPIC will be used to extend their observations to both morning and afternoon hours.
There are numerous ground-based measurements made of ozone (e.g., Dobson network), aerosols (e.g., Aeronet), and UV irradiance (e.g., Brewer network) throughout the day at many locations on the Earth¹s surface. Triana-EPIC can be directly compared with these data throughout the sunlit portion of the day. The most powerful test of the Triana-EPIC data will be for those locations that have instruments from all three networks at the same location as well as an aerosol lidar. Cloud properties will also be validated using other ground sites maintained by the DOE ARM Program. Unlike the satellite comparisons, the ground-based validation will provide high temporal resolution, but at a fixed location.
The combination of satellite and ground-based validations will allow the Triana data to be used with confidence to extend both the satellite and ground-based observations into regions where neither can reach.