Observation And Study Of Solar Radiation In The Earth And Space Of Tibet

Solar radiation not only affects the earth's material conversion and organic matter synthesis,but also plays an important role in energy exchange of agriculture,materials and geo-atmospheric system.Tibet is not only an important part of the trigger and regulator of climate change in the northern hemisphere,but also a fascinating tourist attraction with its unique tourism resources.The study of solar radiation in Tibet can not only guide the scientific and rational utilization of local solar energy resources and alleviate energy pressure,but also provide scientific data for people's outdoor ultraviolet index prediction service.It also provides an important basis for atmospheric research,plant photosynthesis research and material research.Therefore,the observation and study of surface solar radiation is extremely important.In this work,the solar spectrum,solar ultraviolet radiation and total solar radiation in Tibet were observed on the spot by using hyperspectral ultraviolet cosine spectrometer,multi-channel broadband ultraviolet detector and total radiometer,and the reconstructed data set of photosynthetic active radiation in China from 1961 to 2014,ground meteorological and solar data database of NASA and 1:4 million basic geography of China Surveying and Mapping Bureau were combined.Information data are used to study the basic variation characteristics of solar radiation in Tibet.Through data processing and visualization analysis on time series and spatial dimension,it is found that the solar spectral irradiance in Tibet increases continuously from sunrise to noon.The closer to noon,the smaller the spectral line interval,the smaller the gradient of irradiance change,the more obvious the "depression" of spectral line downward,and the more obvious the absorption of the same band in Tibet.The surface solar spectrum in Tibet has the common characteristics of the surface solar spectrum,and the solar ultraviolet spectral irradiance with wavelength less than 290 nm is almost zero;The maximum spectral irradiance is 1.36 W?m-2?nm-1 on January 24,2017,and the corresponding wavelength is 480 nm.Observations in July 2015 show that the spectral irradiance of Beijing and Chengdu is about half of the solar spectrum of Lhasa;In the range of 500~900 nm,the local noon spectral irradiance exceeds the standard reference solar spectral irradiance at the top of the atmosphere;the seasonal average solar ultraviolet radiation in Tibet has the same order of intensity,which is the highest in summer,followed by spring,weaker in autumn and the least in winter;the ultraviolet index in Tibet can reach more than 20 extremely dangerous areas;the total solar radiation in summer is the largest and the minimum in winter in most areas of Tibet throughout the year;the annual photosynthetic active radiation in Tibet is lower in Southeast than in northwest;there is a relatively stable relationship between solar ultraviolet radiation and total radiation,the general trend is opposite to the zenith angle of the sun.