都市夜空亮度地圖建置與解析：以台中市為例

Night Sky Brightness in Urban Areas: Brightness Mapping and Analysis in Taichung City

「天空輝光」為夜間照明的溢散光導致夜空亮度增加的光害現象，除了意味著不必要的照明能源浪費與CO2排放，對自然生態與人類天文活動也會造成影響。本研究為了瞭解都市尺度的夜空亮度光害問題，針對原台中市18條主要道路與重要商圈等地標共計133個測點以手持式夜空亮度計SQM進行實測，並利用Surfer軟體進一步繪製台中市夜空亮度地圖，輔以各測點的人口密度、土地使用分區、平均路面照度、平均沿街立面輝度等資訊，解析都市夜空亮度之成因與關係。調查結果顯示，原台中市平均夜空亮度為15.62 mag/arcsec2，並大致以環中路及鐵路為界，所測得之夜空亮度最亮值為13.41 mag/arcsec2，最暗值為18 mag/arcsec2。此外，人口密度越高，夜空亮度越亮；在各個土地使用分區中，以商業區的夜空亮度最亮，住宅區次之，工業區與綠地農業區較無光害影響，顯示夜空亮度與人類活動及土地使用分區有較顯著的關聯性。尤其夜空亮度較亮的區域，同時也有路面照度高、沿街立面輝度高的情形。都市夜空亮度地圖的建置，不僅提供都市光害的全貌，更能做為大眾認知都市光害問題的起點。同時本研究從人口密度與土地使用等易於掌握的都市規劃因子切入解析，可做為後續都市光害防制研究的參考。

Sky glow, which can be considered light pollution, is an increased brightness of the night sky caused by light spilled from exterior lighting. Sky glow also indicates lighting energy waste and CO2 emissions, and affects natural ecology system and astronomy activity. This study analyzed night sky brightness (NSB) in old Taichung City by surveying 133 points of 18 main roads and 6 landmarks, and transformed GIS data into NSB map with Surfer software. Population density, land use zoning, average road surface illuminance and street-side façade luminance were adopted as relevant factors of NSB for estimation. Results showed that the average NSB of Taichung was 15.62 mag/arcsec2, the brightest NSB was 13.41 mag/arcsec2, and the darkest NSB was 18 mag/arcsec2. The NSB is found to be affected by human factors such as land use zones and population density, especially in commercial districts. Notably, NSB was increased by higher road illuminance and higher street-side building façade luminance. The contribution of NSB map is to provide a general overview of light pollution situation and awareness of urban lighting problems. The NSB mapping results provide a useful reference for follow-up research of the urban light pollution control.