Estimating municipal contributions to cross-border light pollution using VIIRS satellite data: A case study of a national park in Northwest Mexico

• The "zenith sky brightness simulation" application from " www.lightpollutionmap.info " can be used to quickly estimate zenith radiance from VIIRS images. • Zenith radiance contribution to the studied protected area is 75 % from Mexico and 25 % from the USA. • Municipalities with the highest average zenith radiance emitted are two in Mexico and two transboundary (USA). • For the year 2021, the total radiant intensity emitted at the zenith from municipalities adjacent to the Constitution 1857 National Park is 62 % from the USA and 38 % from México. • Population growth trend is more significant on the Mexican border and is closer to the National Park. Light pollution is a form of environmental pollution caused by artificial nighttime illumination that reaches and affects areas often distant from major emission sources, such as protected natural areas for species conservation, ecosystems, and landscapes. These areas typically lack regulations addressing this type of pollution and have few studies on the subject. This study estimates, for the first time, transboundary light pollution from Mexico and the United States of America impacting the Constitution 1857 National Park in Baja California, Mexico. This park represents an area of interest for preserving its landscapes, water sources, and transit zone for migratory birds along the Pacific Flyway. Using VIIRS satellite imagery and considering a 200 km radius around the National Park, light pollution at the zenith of the fourteen municipalities adjacent to the protected area was calculated. Three indicators of light pollution status for the period 2012–2021 were obtained: zenith radiance, radiant intensity, and percentage contribution by municipalities in the border context. The municipalities with the highest zenith radiance values for the period 2012–2021 are Mexicali, Ensenada, San Diego, and Imperial, with the highest radiance contribution being 75 % from Mexico and 25 % from the United States. Such contributions provide crucial data for assessing the transboundary environmental impacts of light pollution and aid in managing the protected area and revising light pollution regulations in these municipalities and counties.