Predicting outdoor service life of polymers and coatings requires knowledge of the spectral power distribution (SPD) of the sunlight and the amount of radiant energy they receive. Standard solar SPDs such as ASTM G173 and ASTM G177 are snapshots of the SPD at a single moment under model conditions. A better measure would be average annual spectral energy distributions (SED) for specific locations, especially benchmark outdoor weathering sites. The annual SED is the energy received at each wavelength over the course of a year. A Smithsonian/NIST collaboration placed SR-18 UV spectroradiometers in Miami, FL, Phoenix, AZ, and Madison, WI during the period 1997-2012, collecting data at ca. 2 nm intervals between 290 and 324 nm. Similar data have been collected at Edgewater, MD for many years. The data are not complete for any year, but gaps could be patched using data from other years. These data sets were compared to data available on-line from ongoing U.S Department of Agriculture (USDA)/Colorado State University outdoor spectroradiometer measurements, after similar patching. The USDA data have fewer points in the UV but extend into the visible portion of the spectrum. The data sets give consistent results and show that the SEDs can be fit by SPDs calculated using the SMARTS 2.9.5 model and satellite ozone data. The annual standard deviations are < 5% for wavelengths > 310 nm. SEDs for average annual radiant energy received by horizontal and 45° south exposures are reported for benchmark sites near Miami and Phoenix. The paper provides a general approach for determining an SED for a location based on SMARTS modeling of the autumnal equinox and subsequent scaling based on reported annual total solar radiant energy.

预测聚合物和涂料的室外使用寿命需要了解太阳光的光谱功率分布（SPD）以及它们接收的辐射能的数量。标准太阳能SPD（例如ASTM G173和ASTM G177）是模型条件下单个时刻的SPD快照。更好的方法是特定位置（尤其是基准室外风化场所）的平均年度光谱能量分布（SED）。年度SED是一年中在每个波长处接收的能量。史密森尼（Smithsonian）/ NIST的合作在1997年至2012年期间将SR-18紫外光谱仪放在了佛罗里达州的迈阿密，亚利桑那州凤凰城和威斯康星州的麦迪逊市，收集的数据约为290和324 nm之间的间隔为2 nm。多年来，在马里兰州Edgewater收集了类似的数据。任何一年的数据都不完整，但是可以使用其他年份的数据来弥补差距。在类似的修补之后，将这些数据集与正在进行的美国农业部（USDA）/科罗拉多州立大学室外分光辐射仪测量的在线数据进行比较。USDA数据的紫外线点较少，但延伸到光谱的可见部分。数据集给出了一致的结果，表明SED可以与使用SMARTS 2.9.5模型和卫星臭氧数据计算出的SPD拟合。波长> 310 nm时，年度标准偏差<5％。据报道，在迈阿密和凤凰城附近的基准站点，水平和向南45°暴露的平均年辐射能的SEDs。