Recently, radiant flux has been proved as a more accurate measure of nighttime light (NTL) compared to radiance. To estimate radiant flux of NTL from nighttime light images accurately, we propose a practical methodology that considers the anisotropy of NTL using the viewing zenith angle (VZA)-radiance quadratic model and the VZA-intensity quadratic model. Our methodology is derived from rigorous physical derivations. To verify the validity and superiority of our proposed methodology, we generated radiant flux products across eight U.S. states using NASA’s Black Marble product. And comparative analysis based on radiant flux calculated using different methods demonstrates that radiant flux calculated using our method provides a more appropriate physical metric for assessing NTL intensity than that derived from previous isotropic models. We conclude that radiant flux considering the anisotropy of NTL is more suitable for quantifying NTL energy and ecological impacts.

Since the outbreak of the Gaza conflict in October 2023, a severe humanitarian crisis has occurred across the entire Gaza Strip. Owing to the challenges of conducting traditional ground-based surveys in the region, satellite images have become critically important as an objective source of information. In response to the demands of humanitarian relief, this study utilized VIIRS, SDGSAT-1, and Yangwang-1 nighttime light (NTL) satellite images to provide a multi-scale assessment of the spatiotemporal dynamics of power supply in the Gaza Strip during the conflict. To reduce errors in quantitatively estimating power supply based on nighttime light, the quality of daily VIIRS NTL images was enhanced and radiometric intercalibrations were conducted between SDGSAT-1 and Yangwang-1 NTL images. The result indicates a severe disruption of power supply in the Gaza Strip as a consequence of the conflict. Specifically, the overall power supply had a sharp decline shortly after the outbreak of the conflict on 7 October 2023 and persisted in a downtrend during the conflict, culminating in a reduction of around 94% as of 1 March 2024. In contrast, the power supply in areas surrounding the Gaza Strip remained relatively stable during the conflict. On 2 December 2023, 24 municipalities were found to have significant reductions in power supply exceeding 90%, and around 95% of buildings had power losses of more than 75%. Furthermore, approximately 70% of hospitals and UNRWA schools in the Gaza Strip were identified to have power outages on 1 January 2024. Among the five governorates of the Gaza Strip, Rafah was the most resilient in terms of power supply during the conflict. This study could make a positive contribution to the timely assessments of the Gaza conflict and support the implementation of humanitarian relief efforts.