First Global Analysis of Saturation Artifacts in the VIIRS Infrared Channels and the Effects of Sample Aggregation

Abstract

Unlike previous spaceborne Earth observing sensors, the Visible Infrared Imaging Radiometer Suite (VIIRS) employs onboard sample aggregation to reduce downlink bandwidth requirements and preserve spatial resolution across the scan. To examine the potentially deleterious impacts of onboard sample aggregation when encountering detector saturation, nearly four months of the National Oceanic and Atmospheric Administration's Nightfire product are analyzed, which contains a subset of the hottest observed nighttime pixels. An empirical method for identifying saturation is devised. The M12 band (3.69 μm) is the most frequently saturating band with 0.15% of the Nightfire pixels at or near the ~359-K detector saturation limit; some saturation is also found in M14, M15, and M16 (8.58, 10.74, and 11.86 μm). Artifacts consistent with detector saturation are seen with M12 temperatures as low as 330 K in the scene center. This partial saturation and aggregation influence must be considered when using VIIRS radiances for quantitative characterization of hot emission sources such as fires and gas flaring.