HY Ultraviolet Imaging and Calibration Sensor

The HY Ultraviolet Imaging and Calibration Sensor (UVI) is a passive UV-A instrument flown on the HY-1D ocean colour satellite.^[1] It carries two UV-A spectral bands centred at approximately 355 nm (345-365 nm range) and 385 nm (375-395 nm range), each with approximately 20 nm bandwidth.^[1] Spatial resolution and swath parameters are not publicly disclosed by the operator.^[1][2] The UVI serves two documented functions in the HY-1D payload complement: providing atmospheric correction inputs for turbid coastal water colour retrieval, and supporting vicarious calibration of the co-flown Chinese Ocean Colour and Temperature Scanner (COCTS).^[3][1] Vicarious calibration using the UVI has been validated against in-situ measurements for ocean colour retrieval on the HY-1C mission.^[3]