Study On The Change Of Solar Radiation And The Influence Of Dust In The Northern Margin Of Taklimakan Deser

Solar radiation is the main source of energy for various physical processes in the natural environment,the basic driving force that drives the formation and movement of weather,climate,and the main source of energy for terrestrial ecosystems.The solar radiation reaching the ground is mainly affected by astronomical factors and the atmosphere of the earth.Studies have shown that different latitudes and different underlying surfaces have obvious differences in the characteristics of radiation changes.The solar radiation in desert areas is more obviously affected by weather.One of the radiation characteristics in desert areas is that they are strongly affected by aerosols such as dust in the air,and their function is to scatter and absorb incident solar radiation.Strong sand dust events in China mainly occurred in the Taklimakan desert in China.In view of this,this paper uses the 2018 radiation observation data of the Xiaotang Radiation Observation and Experiment Station on the northern edge of the Taklimakan Desert to analyze the annual and seasonal changes of total radiation,direct radiation and scattered radiation in the Xiaotang area,discuss the impact of sand and dust on radiation,and three Evaluate and analyze the spatial variation of the average downward shortwave radiation in the Tarim Basin on the time scale of the reanalysis data(ERA-5,MERRA-2 and JRA-55)in the Xiaotang area.Get the following conclusions:(1)In 2018,the total radiation,direct radiation,and scattered radiation in Xiaotang showed a fluctuating distribution with obvious seasonality.The annual total amount of the three was 5781.8,2337.9 and 3323.8 MJ·m^-2,respectively.The total radiation direct radiation peaks in July(679.8MJ·m^-2);the direct radiation peaks in Aug(317.3 MJ·m^-2);the total scattered radiation reached the peak value in May(455.7 MJ·m^-2),and the three in December reached the lowest value.The total radiation,direct radiation and scattered radiation show a normal distribution in clear days,and the flux of total radiation,direct radiation and scattered radiation at each moment is higher than those in cloudy,floating dust,blowing sand and sandstorm weather.In a continuous dust weather process,compared with a sunny days,the peak values of total radiation and direct radiation in sandstorm weather decrease by 51.57%and 97.33%,while the scattered radiation increases by0.78%.The total radiation and direct radiation are obviously weakened in sand-dust weather,and the scattered radiation value obviously increases in the sand and dust day.(2)In the observation experiment of Xiaotang UAV in November 2019,the concentrations of PM_1.0,PM_2.5 and PM₁₀ were between 3.7-48.5?g·m^-3,5.7-104?g·m^-3 and 2.3-430.4?g·m^-3,respectively.Compared with sunny days,the average concentrations of PM_1.0,PM_2.5 and PM₁₀ in Xiaotang floating dust days increased by 32.5,77.9 and 216.9?g·m^-3,respectively.In Xiaotang area,the average atmospheric transmittance is 0.67 on sunny days and 0.46 on dusty days.When the atmospheric transmittance is 0.5,the ratio of scattered radiation to astronomical radiation(R_d/Q_d)begins to decrease.By studying the probability distribution of radiation sandstorm days in Xiaotang,it is found that the reduction of total radiation by dust is mainly concentrated in the high-value area,and the direct radiation is concentrated in the low-value area.The probability of direct radiation<200 W·m^-2 under sandstorms is 100%.Linear regression was used to analyze the total radiation of different sand and dust weather with the change of the sun's altitude.Under different weather conditions,the highest value of total radiation appeared in sunny days,and the lowest value appeared in sandstorm days.The P₂ of sunny days is larger,and the average P₂ of sunny days,floating dust and sandstorm days are 0.57,0.34,0.17 and 0.08 respectively in Xiaotang.The annual change analysis of direct radiation,scattered radiation flux and AOD in the 550nm band in2018 shows that the annual change of AOD is roughly the same as that of scattered radiation.,reaching the maximum in spring,the minimum in winter and the maximum in May.The two have good consistency,and the magnitude of AOD in May is 0.710.(3)Using the downward shortwave ground observation data from Xiaotang Station on the northern margin of the Taklimakan Desert,the downward shortwave errors of the three reanalysis data(ERA-5,MERRA-2 and JRA-55)were evaluated on the annual,seasonal and monthly scales.Through the evaluation,it was found that the data set of MERRA-2 performed better than ERA-5,and JRA-55 performed the worst.Through error evaluation,it is found that MERRA-2 performs better.The MERRA-2 reanalysis data is used to analyze the spatial variation characteristics of the average downward shortwave radiation flux in the Tarim Basin.The overall trend of the average downward shortwave radiation in the Tarim Basin follows the change of latitude.The higher the latitude,The downward short wave gradually decreases.In terms of seasonal spatial changes,the average downward shortwave radiation value in summer is the high-value areas are mainly concentrated in the southwestern part of the Tarim Basin(357 W·m^-2.).