Robert E. Ryan Innovative Imaging and Research Corp.
Mary Pagnutti Innovative Imaging and Research Corp.
Timothy Ruggles South Dakota State University
Kara Burch Innovative Imaging and Research Corp.
Larry Leigh South Dakota State University
Dennis Helder South Dakota State University
David Aaron South Dakota State University
Changyong Cao NOAA NESDIS STAR

15D

The high sensitivity of the VIIRS Day-Night Band (DNB) High Gain Stage (HGS) on the Suomi NPP and NOAA-20 satellites is enabling unparalleled investigations of nighttime artificial lighting and atmospheric properties. Time series of artificial night lights can be used to monitor changes in human activity and atmospheric conditions if both the instrument and imaged light source are stable. While the VIIRS DNB is calibrated, the large dynamic range of the instrument prevents the direct use of the on-board solar diffusers for the HGS. In this paper, we present the first NIST-traceable point source designed to absolutely radiometrically calibrate the VIIRS DNB HGS and discuss how this active source can be used to improve VIIRS DNB time series analyses. We discuss the design and operation of the novel calibration source and provide early results along with supplementary atmospheric measurements. The active source uses an integrating sphere illuminated with four 1-KW High Pressure Sodium (HPS) lamps; lamp radiance is measured by a NIST-traceable spectroradiometer and monitored with a photodiode. The active calibration source is controlled remotely and automated to operate only during a satellite overpass with relatively clear atmospheric conditions. The source is housed in a moveable trailer and is deployed in South Dakota during the summer and Mississippi during the winter. This new active point source complements current traditional calibration techniques, which are based on radiance-based lunar illumination (extended sources), and helps improve our understanding of the point source radiative transfer needed to develop nighttime artificial light source applications. In the paper we demonstrate how this stable light source can also be used to measure ground-to-space atmospheric transmission, and we show how this new capability can help identify other stable light sources near the calibration source that can also be used for atmospheric monitoring.

16:15 Laying the Foundation for Improved Night Lights Time Series from the VIIRS DNB, Robert E. Ryan