Documentation for the VIIRS Plus DMSP Change in Lights(VIIRS+DMSP dLight)

The VIIRS Plus DMSP Change in Lights (VIIRS+DMSP dLIGHT) data set fuses nighttime lights imagery from the U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) with a stable night light composite from the next generation Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band to map the spatial distribution and temporal evolution of global nighttime lights between 1992 and 2015.The product visualizes changes in both brightness and extent of nocturnal low lights over two decades while minimizing the spatial overextent (overglow) and bright saturation that compromise the DMSP-OLS composites. The map product utilizes annual DMSPOLS stable lights composites, produced by the NOAA Earth Observation Group and archived at the NOAA National Geophysical Data Center (NGDC), in a tri-temporal global change map. To achieve greater spatial resolution and radiometric accuracy, the DMSP-OLS composites are co-registered and fused with the 2015 VIIRS annual composite from NGDC. The final product therefore retains the spatial detail and dynamic range of the VIIRS product, and the decadal change information from DMSP-OLS images.In the image, warmer colors represent brightening of nighttime lights post-1992, while cooler colors reflect dimming. As with all pan-sharpening approaches, projecting the 1992 to 2013 changes onto the 2015 lighted extent does not necessarily show the true spatial structure pre-2015, but rather shows the temporal evolution of brightness of lighted areas circa 2015, without the effects of overglow or saturation.