||Since 1994, NGDC has had an active program focused on global mapping of nighttime lights using the data collected by the Defense Meteorological Satellite Programâs Operational Linescan System (DMSP-OLS) sensors. The basic product is a global annual cloud-free composite, which averages the OLS visible band data for one satellite from the cloud-free segments of individual orbits. Over the years, NGDC has developed automatic algorithms for screening the quality of the nighttime visible band observations to remove areas contaminated by sunlight, moonlight, and the presence of clouds. In the Stable Lights product generation, fires and other ephemeral lights are removed based on their high brightness and short duration. Background noise is removed by setting thresholds based on visible band values found in areas known to be free of detectable lights. In 2010, NGDC released the version 4 time series of Stable Lights, spanning the years 1992-2009. These are available online at <http://www.ngdc.noaa.gov/dmsp/downloadV4composites.html>.