地面太阳光谱记录了太阳光经历大气层的烙印与信息, 为大气环境、 生态保护等研究提供实地依据。 西藏高原空气稀薄, 地面太阳辐射超强, 观测西藏地面太阳光谱为太阳能利用提供实地数据。 文章较系统地报道了西藏地面太阳光谱的实地观测结果, 为相关高原科学研究提供高精度数据。 利用RAMSES光谱仪、 CMP6太阳总辐射仪和NILU-UV太阳紫外辐射仪对西藏不同地区、 不同季节太阳光谱、 太阳总辐射和太阳紫外线进行了全方位的实地观测研究。 观测研究了高海拔的西藏拉萨和那曲以及低海拔的北京和成都的光谱特征; 研究了拉萨二分二至当地正午（北京时间13:55时）太阳光谱观测结果; 对西藏地面光谱与AM1.5和AM0标准光谱进行了对比研究。 观测研究了西藏拉萨和那曲太阳总辐射、 太阳紫外线强度特征。 研究发现拉萨夏季可见和红外区光谱光强度甚至超过AM0光谱相应波长的强度, 即: 拉萨地面可见光和红外光强度偶尔超过大气层顶部的相应波长光强, 是由部分云的反射增量所致; 拉萨光谱谱峰出现在波长476.6 nm左右, 在2017年的夏至观测到的最大值为2.331 W·m-2·nm-1。 然而, 对太阳紫外线（280～400 nm）光谱的观测发现地面太阳紫外区的光谱强度总是明显低于AM0光谱相应区光强, 表明短波的紫外光被大气臭氧有效吸收。 虽然拉萨海拔3 680 m, 但通过对拉萨当地正午太阳紫外光谱分析发现拉萨地面波长小于300 nm的太阳紫外光谱强度几乎为零, 表明波长小于300 nm的太阳紫外线被大气层吸收, 没有到达地面。 同时, 研究了西藏高海拔太阳光谱与北京、 成都低海拔太阳光谱特征, 揭示了各地大气成分、 含量等诸多信息。 报道了2010年7月—2013年12月期间西藏太阳总辐射的观测结果; 结果显示拉萨当日太阳总辐射最大值中约18%超过了太阳常数（1 367 W·m-2）。 观测发现拉萨太阳总辐射瞬时最大值达到了1 756.09 W·m-2（2011年6月24日）。 报道了2008年7月—2013年12月期间西藏太阳紫外线的观测结果; 结果显示拉萨和那曲UVA日最大值平均值约为67 W·m-2, UVB日最大值平均值约为5.1 W·m-2; 拉萨和那曲当日太阳紫外线A和紫外线B最大值变化趋势保持了很好的一致性, 在5年多的观测期间紫外线强度没有出现明显的增强或减弱趋势。

The terrestrial solar spectrums record the imprints and information of sunlight passing through the atmosphere, it provides practical information for the study of atmospheric environment and ecological protection. Tibet is one of the world’s best-known areas with strongest solar radiation. Observation of solar radiation on the ground in Tibet can provide field data for solar energy utilization and research on atmospheric environment etc.. A systematic field observation was conducted to observe the surface solar spectrums, solar global irradiance and solar UV irradiance in Tibet by using the German RAMSES hyperspectral Irradiance Sensors, the Dutch CMP6 Pyranometers and the Norwegian NILU-UV Multi-filter Radiometers. The monthly spectral characteristics of Lhasa, Tibet, for 2017 were observed. The results of solar spectral observations at the local noons (13:55BJ) of Lhasa for the two equinoxes and the two solstices were reported. The ground spectra of Tibet were compared with the standard spectra of AM1.5 and AM0. The characteristics of global solar irradiance and solar ultraviolet intensity in Lhasa and Naqu of Tibet were observed and studied. It is found that the spectral intensities for visible and infrared lights in summer even exceed the corresponding wavelength spectral intensities of the AM0 spectra in Lhasa. In other words, the spectral intensities for visible and infrared lights on the surface of Lhasa occasionally exceed the spectral intensities of the corresponding radiation at the top of the atmosphere. The maximum spectral value of Lhasa usually occurs at wavelengths of about 476.6 nm, and the maximum observed in summer solstice in 2017 is about 2.331 W·m-2·nm-1. However, the observation of solar UV radiation (280～400 nm) spectrum shows that the spectral intensity of the ground solar UV region is always significantly lower than that of the corresponding intensity of the AM0 spectrum. Although Lhasa is located at about 3 680 meters above sea level, the ground measurements of the local noon solar UV spectrums indicate that the wavelengths less than 300 nanometers of UV irradiances are almost zeroes in Lhasa, which means that the solar UV irradiance with wavelengths less than 300 nm is absorbed by the atmosphere and does not reach the ground. It indicates that the short-wave solar UV radiations are absorbed effectively by atmospheric ozone. At the same time, the characteristics of the solar spectra at the high altitude of Tibet and lower places in Beijing and Chengdu are observed and studied, and the information on atmospheric composition and content in various places are revealed. The results of the solar global irradiance in Tibet during July of 2010—December of 2013 are reported. The results show that about 18% of the global irradiances in Lhasa exceed the solar constant (1 367 W·m-2). It is found that the instantaneous maximum value of the global irradiance in Lhasa reaches 1 756.09 W·m-2 (June 24, 2011). The observation results of solar UV radiation in Tibet during July of 2008—December of 2013 are also reported. The results show that the averaged daily maximum value of UVA for both Lhasa and Naqu is about 67 W·m-2, and the maximum value of UVB for the same places is about 5.1 W·m-2. The daily maximum values of UVA and UVB for both Lhasa and Naqu are maintained a good consistency. During the observation period of more than 5 years, there was no obvious enhancement or weakening trend for the UV intensities.