Natural Sounds and Night Skies Division, National Park Service, 1201 Oakridge Dr., Suite 100, Fort Collins, CO, 80525, USA.
Natural Sounds and Night Skies Division, National Park Service, 1201 Oakridge Dr., Suite 100, Fort Collins, CO, 80525, USA.
J Environ Manage. 2021 Aug 15;292:112776. doi: 10.1016/j.jenvman.2021.112776. Epub 2021 May 19.
The US National Park Service (NPS) Night Skies Program measured changes in sky brightness resulting from a countywide lighting retrofit project. The retrofit took place in Chelan County, a gateway community to North Cascades National Park and Lake Chelan National Recreation Area in Washington State. The county retrofitted all 3693 county-owned high pressure sodium (HPS) street lamps to full cutoff LEDs. This number is about 60% of the County's total outdoor street and area lights. About 80% of the newly installed lights were 3000 K in color temperature and 20% were 4000 K. The 4000 K LEDs were used to meet Washington State Department of Transportation guidelines. To measure sky brightness, we used the NPS night sky camera system before the retrofit started in 2018 and after its completion in 2019. These images were photometrically calibrated and mosaicked together to provide hemispherical images in V band. For comparison with our ground-based measurement, we obtained the satellite imagery taken by Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership satellite. Our measurements show that the post-retrofit skyglow became brighter and extended higher in the sky, but upward radiance, as measured by the day-night band radiometer, decreased. These divergent results are likely explained by a substantial increase in light emitted at wavelengths shorter than 500 nm, and a relative decrease in upward light emission due to better shielded luminaires. These results also demonstrate that earlier models relating VIIRS day-night band data to skyglow will - at a minimum - require substantial revision to account for the different characteristics of solid state luminaires.
美国国家公园管理局（NPS）夜空计划测量了由于全县照明改造项目导致的天空亮度变化。该改造项目发生在华盛顿州北卡斯卡德国家公园和切兰湖国家游乐区的门户社区切兰县。该县将所有 3693 个县拥有的高压钠（HPS）路灯全部改装成全截止 LED。这一数字约占该县户外街道和区域照明总数的 60%。约 80%的新安装灯具的色温为 3000 K，20%为 4000 K。4000 K 的 LED 用于满足华盛顿州交通部的指导方针。为了测量天空亮度，我们在 2018 年改造开始前和 2019 年改造完成后使用了 NPS 夜空摄像系统。这些图像经过光度校准并拼接在一起，以提供 V 带的半球形图像。为了与我们的地面测量结果进行比较，我们获得了搭载在 Suomi 国家极地轨道伙伴关系卫星上的可见红外成像辐射计套件（VIIRS）拍摄的卫星图像。我们的测量结果表明，改造后的天空辉光变得更亮，在天空中延伸得更高，但天-地波段辐射计测量的向上辐射却减少了。这些不同的结果可能是由于 500nm 以下波长的光发射大量增加，以及由于更好的屏蔽灯具导致向上光发射相对减少所导致的。这些结果还表明，早期将 VIIRS 天-地波段数据与天空辉光联系起来的模型至少需要进行重大修订，以考虑到固态灯具的不同特性。
