Abstract: Strong solar irradiance in Tibetan Plateau provides heat source for the plateau's atmosphere, driving atmospheric circulation of East Asian and the "butterfly effect" of global climate change. Synchronous observation of the ground solar spectral characteristics in the region can provide effective field data for studying the changes of the ground atmospheric environment, ecological environment and the utilization of solar energy resources. Using the international standard high-precision solar spectrometers RAMSES-ACC-VIS and SolarSIM-G, the solar spectra of Lhasa, Nyingchi, Nagchu, Shigatse and Mt. Everest in Xizang, China, were observed during 2020 to 2021. Synchronous observation of full band solar spectra (wavelength covering from 280 nm to 2500 nm) at high altitude in Xizang was conducted for the first time, the spatial distribution characteristics of solar spectral irradiance at multiple points in Xizang were studied, and the extinction factors such as absorption and scattering of solar spectrum at high altitude in Xizang were qualitatively analyzed. The results show that the annual average solar spectral irradiance in Shigatse and the Mt. Everest are the strongest, with the annual average spectral peak of more than 0.83 W/ (m2·nm), the spectrum of Lhasa region is only inferior to that of Shigatse and Mt. Everest regions, with an average annual peak of about 0.73 W/(m2·nm), the annual average solar spectrum in Nagchu is lower than that in Lhasa, with a peak value of about 0.53 W/(m2·nm), and Nyingchi has the lowest solar spectrum. In terms of the spatial distribution characteristics of solar spectral irradiance, it is found that on the winter solstice, the spatial distribution of Xizang's spectral irradiance basically follows the zonal law, that is, the radiation intensity decreases with the increase of latitude, while on the summer solstice, the zonal regularity in Xizang is not so obvious due to rainy season weather.

Key words: Xizang, solar spectrum, multipoint observation, ecological environment