Lighting types of China's coastal zone

Nighttime Light (NTL) is highly concentrated in China's coastal zone, leading to negative health impacts on both humans and wildlife. Particularly, in recent years, the widespread adoption of broad-spectrum Light-Emitting Diode (LED) light, a low-carbon technology providing substantial increases in luminosity, has led to certain ecological consequences. Thus, information regarding spatial distribution and composition of different NTL types is essential for formulating sustainable strategies that balance nighttime public security, energy consumption, and ecosystem conservation. However, the availability of such information remains limited. To address this challenge and meet the demand, we developed two new light indices, namely the Ratio Red Light Index (RRLI) and Ratio Blue Light Index (RBLI), based on SDGSAT-1 Glimmer Imager (GLI) multispectral NTL data. We then proposed a threshold method and applied it to the entire coastal zone of China to identify White LED (WLED), Red LED (RLED), and Other lights (Other). Results showed the following. (1) In the coastal zone of China, the total lighting area was 20,517 km2, including 20,257 km2 of terrestrial lights and 260 km2 of offshore lights; (2) WLED light covered 67% (13,727 km2) of all lighting areas, while RLED lights accounted for only 1% (220 km2); (3) Guangdong had the largest lighting area (5221 km2), with the proportion of WLEDs being the highest among all coastal provinces (almost 90%); (4) The proportions of lighting areas were relatively low in Guangxi, Liaoning, and Hebei. This study represents the first attempt to identify NTL types over large regions at a finer spatial resolution. The approach proposed, including the light indices of RRLI and RBLI, as well as the defined thresholds, is universal and robust for use in NTL type classification. The developed lighting type map, containing comprehensive information on the spatial distribution and composition of NTL, could facilitate the sustainable management of China's coastal zones.夜间灯光（Nighttime Light, NTL）高度集聚于中国沿海区域，对人类与野生生物均会产生负面健康影响。近年来，广谱发光二极管（Light-Emitting Diode, LED）作为一种可显著提升亮度的低碳技术被广泛普及，由此引发了一系列生态后果。因此，掌握不同类型夜间灯光的空间分布与组成信息，对于制定兼顾夜间公共安全、能源消耗与生态保护的可持续发展策略至关重要。但目前此类信息的可获取性仍较为有限。为应对这一挑战并满足相关需求，本研究基于SDGSAT-1微光成像仪（Glimmer Imager, GLI）的多光谱夜间灯光数据，构建了红光比值指数（Ratio Red Light Index, RRLI）与蓝光比值指数（Ratio Blue Light Index, RBLI）两种新型灯光指数。随后我们提出了一种阈值分割方法，并将其应用于中国全沿海区域，以识别白光LED（White LED, WLED）、红光LED（Red LED, RLED）以及其他灯光（Other）。研究结果如下：（1）中国沿海区域总灯光面积达20517平方千米，其中陆地灯光面积20257平方千米，近海灯光面积260平方千米；（2）白光LED灯光占所有灯光面积的67%（13727平方千米），而红光LED灯光仅占1%（220平方千米）；（3）广东省灯光面积最大，达5221平方千米，且其白光LED占比在所有沿海省份中最高（近90%）；（4）广西、辽宁与河北省的灯光面积占比相对较低。本研究首次实现了大区域范围内更高空间分辨率的夜间灯光类型识别。本研究提出的方法（包括RRLI与RBLI灯光指数以及所设定的阈值）在夜间灯光类型分类中具备通用性与鲁棒性。本研究构建的包含夜间灯光空间分布与组成信息的灯光类型分布图，可为中国沿海区域的可持续管理提供支撑。