Monitoring Nighttime Light Change from Daily NASA's Black Marble Product Suite

NASA's operational atmospheric- and Lunar-BRDF-corrected daily Black Marble nighttime light (NTL) product (VNP46), generated from Suomi-NPP and NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) observations, enables the quantitative analysis of human activity and human behavior dynamics with reduced uncertainties. Timely and continuous change detection algorithm fully utilizing the rich daily DNB observations is lacking. In this study, we developed a Viewing Zenith Angle (VZA) stratified COntinuous monitoring of Land Disturbance (COLD) algorithm (VZA-COLD) to continuously detect NTL change at 15-arc-second spatial resolution. The change detection algorithm maps the global NTL changes with daily updating capability to provide knowledge regarding sustainable human-environment systems, inequalities, and management of energy and natural resources relevance to the United Nations Sustainable Development Goals (SDGs). Specifically, we divided the NTL observations into four VZA intervals (0-20°, 20°-40°, 40°-60°, and 0-60°) to mitigate the combined impacts of viewing geometry and surface conditions (e.g., building heights, vegetation canopy covers, etc.). Unified sets of NTL changes were detected continuously based on the actual observations and model predictions of each VZA interval. The final NTL change maps were generated by assembling the changes detected from the four VZA intervals and excluding consistent dark pixels. Results showed that the VZA-COLD algorithm reduced the DNB data temporal variations caused by disparities among different viewing angles and surface conditions and successfully detected NTL changes with an overall accuracy of 99.71%, a user's accuracy of 87.18%, and a producer's accuracy of 68.88% at six globally distributed test sites.