PAYNE INSTITUTE COMMENTARY SERIES: COMMENTARY

By Tilottama Ghosh

July 29, 2026

VIIRS Nightfire satellite observations from July 27^th, 2026, effectively identify active combustion sources over large geographic areas, enabling the simultaneous monitoring of multiple wildfire events. The largest and most intense cluster of fire detections is located in Ávila Province, west of Madrid, while another major concentration occurs in Guadalajara Province, northeast of Madrid. Additional wildfire activity is observed farther east in the mountainous areas of the Valencian Community near Castellón, approximately 300 km east of Madrid, indicating multiple active wildfire complexes across central and eastern Spain. The majority of detections correspond to temperatures between 400 and 1000 K (purple markers), with fewer hotspots exhibiting temperatures between 1000 and 1400 K (blue and green markers), indicating that most fires were of moderate thermal intensity.

Overall, spatial distribution shows that wildfire activity is concentrated in the mountainous terrain surrounding Madrid rather than within the city center, with Valencia similarly situated outside primary fire zones. While urban cores remain structurally protected, the surrounding wildland-urban interface (WUI) faces severe vulnerability, directly driving mass emergency evacuations and infrastructure damage in adjacent towns.

This graph shows a VIIRS Nightfire (VNF) analysis (one of the purple placemarks from the cluster in Avila Province), which is unique because it fits a Planck curve to multi-spectral nighttime data to simultaneously calculate a fire’s temperature, area, and radiative heat. By separating thermal wavelengths into two distinct Planck curves—a background temperature of 297 K (black curve) and a heat source temperature of 955 K (red curve)—the algorithm aligns with actual satellite sensor measurements (the stars). This curve fitting allows VNF to isolate an active fire source with a footprint area of 1143.44 m2 emitting a massive 53.92 MW of radiative heat.

VIIRS Nightfire (VNF) satellite detections are revealing active thermal anomalies advancing through the pine forests west of Bordeaux in France. Positioned directly along the forest-urban interface in the Gironde region, these fire fronts pose a direct threat to the outer edges of the metropolitan area, triggering local evacuations and forcing emergency crews to work continuously to hold the perimeter.

These regional perspectives highlight the operational value of VIIRS Nightfire observations for emergency responders managing real-time evacuation zones, establishing situational awareness, and evaluating active fire perimeters.

ABOUT THE AUTHOR

Tilottama Ghosh
Research Associate, Earth Observation Group

Tilottama (Tilo) completed her PhD in geography from the University of Denver. Her training and educational background in geography, demography, economics, remote sensing, and Geographic Information Systems (GIS) helped to shape-up her interests, career and passion. Her research interests include nighttime lights, remote sensing, sustainable science, human geography, and spatio-temporal research using remote sensing, and Geographic Information Systems (GIS). She has about fourteen years of experience working with low light imaging data from the U.S. Air Force Defense Meteorological Satellite Program (DMSP), and Visible Infrared Imaging Radiometer Suite (VIIRS) data, from 2013 onwards. She is responsible for creating the nightly, monthly, and annual, VIIRS nighttime lights products, and the other two flagship products, VIIRS Boat Detection (VBD), and VIIRS Nightfire(VNF), as well as the processing of the DMSP monthly and annual cloud-free composites. Along with her team members she is responsible for conceptualizing, and testing of the processing algorithms, creating metadata documenting generated data products, fulfilling data requests related to the nighttime lights products and the DMSP archive, providing training in the use and implementation of nighttime lights software to scientists and researchers, documenting DMSP and VIIRS algorithms and accomplishments through manuals, conference proceedings, and journal submissions. She conducts socio-economic research using nighttime Earth Observation Group (EOG) products and official socio-economic data at local and global scales. She publishes such work in peer -reviewed journals, conference proceedings, and book chapters.

ABOUT THE PAYNE INSTITUTE

The mission of the Payne Institute at Colorado School of Mines is to provide world-class scientific insights, helping to inform and shape public policy on earth resources, energy, and environment. The Institute was established with an endowment from Jim and Arlene Payne and seeks to link the strong scientific and engineering research and expertise at Mines with issues related to public policy and national security.

The Payne Institute Commentary Series offers independent insights and research on a wide range of topics related to energy, natural resources, and environmental policy. The series accommodates three categories namely: Viewpoints, Essays, and Working Papers.

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DISCLAIMER: The opinions, beliefs, and viewpoints expressed in this article are solely those of the author and do not reflect the opinions, beliefs, viewpoints, or official policies of the Payne Institute or the Colorado School of Mines.