NOAA-20 VIIRS Level-3 Global Mapped Diffuse Attenuation Coefficient of Downwelling Irradiance (KD) - Near Real-time (NRT) Data, version 2022.0

As such, the inputs and the calibration used are less than optimal. Near real-time products provide a snapshot of the data during a short time period within a single orbit.

The KD data suite provides diffuse attenuation coefficient of downwelling irradiance at 490 nm, Kd_490, which quantifies how quickly blue-green light diminishes with depth—an indicator of water clarity and the depth to which sunlight penetrates. Kd_490 is generated from ocean-color reflectance using the KD2 algorithm. Lower values indicate clearer water (deeper light penetration); users commonly apply Kd_490 to estimate euphotic depth, track coastal water quality and turbidity, interpret bloom/light environments, and supply inputs to biogeochemical and ecosystem models.