精确观测地面太阳光谱能为反演大气环境、 利用太阳能资源、 保护植物生态等提供实地数据。 对比目前卫星和地面观测结果显示由于海拔高、 空气稀薄等因素西藏是地球上瞬时太阳辐照度最强的地区之一, 观测西藏太阳光谱变化特征对研究强辐射环境下人类健康、 生态变迁、 太阳能利用等诸多领域具有独特的意义。 2020年—2021年利用德国RAMSES-ACC-VIS光谱仪和加拿大SolarSIM-G高精度光谱仪对西藏五个高海拔地区(拉萨、 林芝、 那曲、 日喀则、 定日)进行了为期一年的太阳光谱观测研究。 首次获得了西藏多地完整一年的太阳光谱实地数据, 记录了每隔一分钟全天太阳紫外线、 光合有效辐射和红外辐射光谱变化特征。 分析研究了西藏各地全年日平均太阳光谱特征, 发现全年日均最高光谱峰值1.12 W·m^-2·nm^-1出现在波长477.30 nm处。 研究了西藏典型高原拉萨地区太阳光谱随季节性的变化特征, 分析了其二分二至光谱辐照度变化区间, 发现拉萨夏至日均光谱辐照度比冬至高约一倍多, 夏至光谱峰值1.13 W·m^-2·nm^-1, 冬至0.43 W·m^-2·nm^-1。 西藏日喀则全年太阳光谱变化浮动比拉萨的小, 各节气光谱变化范围比较集中, 夏至和冬至光谱峰值之差比拉萨的小。 研究了西藏各地太阳光谱年平均辐照度特征, 发现日喀则和珠峰平地年平均太阳光谱辐照度非常接近, 两地光谱峰值均约为0.83 W·m^-2·nm^-1; 拉萨年均光谱峰值约为0.73 W·m^-2·nm^-1, 略低于日喀则和定日; 那曲年均光谱曲线最低, 峰值仅为0.53 W·m^-2·nm^-1。 太阳光谱年均值和太阳能资源不同地区分布特征对西藏高原开发利用太阳能资源具有重要的应用价值。 为了比较西藏高原与内地平原太阳光谱特征, 同步观测研究了高海拔拉萨(3 693 m)和低海拔北京(32 m)的晴天太阳光谱。 2021年6月3日两地均为晴天, 分析了两地当地正午太阳光谱特征, 发现拉萨正午全波段光谱积分值比北京高约20%, 比大气质量AM0的仅低5%左右; 当日正午拉萨光谱峰值达1.83 W·m^-2·nm^-1, 北京为1.41 W·m^-2·nm^-1; 当日正午拉萨太阳紫外光谱积分值比北京高约15%。

Accurate measurement of solar spectra on the ground can provide field data for the inversion of the atmospheric environment, utilization of solar energy resources, and protection of plant ecology, etc. . According to current satellite and ground-based observations, Tibet is one of the regions with the strongest instantaneous solar irradiance on the earth due to factors such as high altitude and thin air. Observing the characteristics of solar spectral changes in Tibet is of unique significance for studying various fields such as human health, ecological changes, and solar energy utilization under strong radiation environments. From 2020 to 2021, we use the German RAMSES-ACC-VIS spectrometers and the Canadian SolarSIM-G high-precision spectrometers to study the solar spectra of five high-altitude areas in Tibet (Lhasa, Nyingchi, Nacqu, Shigaze and Tingri) for a whole year. For the first time, obtain one-year solar spectral field data from many places in Tibet, and record the daily averaged spectral irradiance of solar ultraviolet, photosynthetically active radiation and infrared radiation for every minute. The annual daily averaged solar spectral characteristics in Tibet are analyzed and studied. It is found that the highest daily averaged spectral peak of 1.12 W·m^-2·nm^-1 appeared at the wavelength of 477.30 nm. The seasonal variation characteristics of the solar spectra in Lhasa, a typical plateau region in Tibet, are studied, and the range of spectral irradiance between the solstices. It is found that the daily averaged spectral irradiance at the summer solstice in Lhasa is more than twice as high as that at the winter solstice. The peak value of the spectral irradiance at the summer solstice is about 1.13 W·m^-2·nm^-1, and that at the winter solstice is 0.43 W·m^-2·nm^-1. The fluctuation change of the annual solar spectra in Shigaze, Tibet is smaller than that in Lhasa. Its spectral change of each solar term is relatively concentrated. The difference between the summer and winter solstice's peak spectral values is smaller than in Lhasa. The characteristics of annually averaged solar spectral irradiance over Tibet are studied. It is found that the annually averaged solar spectral irradiance of Shigaze and Mt. Everest is very close, and the peak value of the two places is about 0.83 W·m^-2·nm^-1; The annually averaged spectrum of Lhasa is slightly lower than that of Shigaze and Tingri, with a peak value of about 0.73 W·m^-2·nm^-1; The annually averaged spectral curve of Nacqu is the lowest, with a peak value of only 0.53 W·m^-2·nm^-1. The annual mean value of the solar spectrum and the distribution characteristics of solar energy resources in different regions have important application value for developing and utilizing solar energy resources on the Tibetan Plateau. In order to compare the solar spectral characteristics of the Tibetan Plateau and the mainland plain, clear sky solar spectra of high altitude Lhasa (3 693 m) and low altitude Beijing (32 m) are observed and studied simultaneously. On June 3, 2021, both places are clear sky days; analyzing the local noon solar spectral characteristics in both places, it is found that the full band spectral integral value of Lhasa at noon is about 20% higher than that of Beijing, and only about 5% lower than that of Air Mass AM0. the peak of the local noon spectrum of Lhasa reaches 1.80 W·m^-2·nm^-1, and that of Beijing is about 1.40 W·m^-2·nm^-1; The solar UV spectral integral value of local noon in Lhasa was about 15% higher than that of in Beijing.