Analysis Of Temporal Variation Characteristics Of Total Solar Radiation And Long-wave Radiation On The Surface Of Yangbajing Area In Tibe

Solar radiation is the main source of energy of the earth,and it is the basic source of various physical processes and biological activities on the surface of the earth.The solar radiation is of great important for the radiation balance of the ecosystem and the formation and evolution of the climate.Moreover,solar energy as a safe and environmentally friendly renewable energy,its development and utilization has become one of the concerns of scientists all over the world.The Qinghai-Tibet Plateau,with its unique geographical location(high altitude,low latitude)and atmospheric conditions(high atmospheric transparency,low ozone concentration,strong solar radiation),has become the best area for studying solar radiation and developing and utilizing solar energy.Using the two-year ground-based radiation data from Jan.2020 to Dec.2021 measured by the EKO MR-60 four-component radiation sensor at Yangbajing station on the Qinghai-Tibet Plateau,the characteristics of variation of the five radiation components(i.e.the total solar radiation,the upward shortwave radiation,the downward longwave radiation,the upward longwave radiation,and the surface net radiation),surface albedo,and the cloud-induced shortwave radiative forcing with time(i.e.day,month,and season)are mainly analyzed in this thesis.The results show that the monthly variation of the total solar radiation and the net surface radiation in Yangbajing area show a significant unimodal pattern,with the highest value found in June and the lowest value in December.The lowest monthly averaged values of the downward longwave radiation and the upward longwave radiation found in January,while their highest values are found in July and June,respectively.Moreover,for the upward shortwave radiation,its highest monthly mean value appears in April and the lowest in September.The diurnal and annual variation trends of the surface albedo in this area show a"U-shaped"distribution,with the highest value found in February and the lowest in July.The cloud-induced shortwave radiative forcing in this area is negative throughout the year,ranging from-22.4 W/m~2 to-233.6 W/m~2,with the highest value appeared in July and the lowest value in November.In addition,the phenomenon that the instantaneous value of the measured total solar radiation exceeds the solar constant mainly occurs in spring,summer and autumn,and summer is the most frequent one.