大连市四个季节典型晴朗夜晚的亮度变化数据

"本数据库使用定点式监测方法，将天空质量仪SQM-LU-DL放置在辽宁省大连市甘井子区大连理工大学建筑与艺术学院屋顶，每隔五分钟记录一次星等亮度数据，获得2017-2018年全年长时间序列的大连市夜间灯光亮度值，从而得到稳定人工照明作用下的城市夜间灯光亮度值，探索监测年份内亮度周期性变化规律。
月亮、空气质量、云层明显对城市夜空亮度有影响，因此为获得稳定人工照明影响的亮度值数据，获取空气质量数据和气象数据，并采用以下步骤将受自然因素影响的数据剔除：（1）剔除满月前后七天的测量值；（2）剔除接近日出和日落时间的数据；（3）剔除云量值不为零的数据。
在稳定人工照明影响的亮度值数据基础上选择每个季节中的典型夜晚作为研究对象，研究时间段为从自然光到人工光，人工光再过渡到自然光的全过程，包含了黄昏、傍晚、夜晚、午夜、凌晨、清晨五个阶段，尽量排除其它自然因素影响，按照控制变量原则，保证研究对象诸多自然因素的一致性。以此绘制2017~2018年大连市四个季节典型晴朗夜晚的亮度变化图。"

This database adopts the fixed-point monitoring approach, with the sky quality meter SQM-LU-DL deployed on the roof of the School of Architecture and Fine Arts, Dalian University of Technology, located in Ganjingzi District, Dalian City, Liaoning Province. It records magnitude brightness data every five minutes, acquiring annual long-time series of nighttime light brightness values in Dalian from 2017 to 2018. This allows us to obtain urban nighttime light brightness values under stable artificial illumination and explore the periodic variation patterns of brightness during the monitoring period.

The moon, air quality and cloud cover exert obvious impacts on urban nighttime sky brightness. To isolate brightness data solely affected by stable artificial lighting, air quality and meteorological data were collected, and natural-factor-corrupted data were excluded through the following steps: (1) Exclude measurements taken seven days around the full moon; (2) Exclude data collected near sunrise and sunset times; (3) Exclude data with non-zero cloud cover.

Based on the brightness dataset filtered to reflect only stable artificial lighting impacts, typical nights from each season were selected as research subjects. The selected research time spans the full transition cycle from natural light to artificial light and back to natural light, encompassing five phases: dusk, evening, nighttime, midnight, early morning, and dawn. Other natural confounding factors are minimized as far as possible, adhering to the controlled variable principle to ensure consistency of natural conditions across all research objects. Accordingly, brightness variation charts for typical clear nights across the four seasons of Dalian from 2017 to 2018 were plotted.