The Characteristic Of Surface Radiation And Energy Variation With Usability Of Multi-sources Data Over The Gobi Region In Xinjiang

This paper's characteristics of the surface radiation and energy flux budget of the typical black Gobi desert in the Hami area of eastern Xinjiang under different time scales and weather conditions were analyzed by the radiation observation system and the open-path eddy covariance system data from the Hongliuhe Gobi Land-Atmosphere Interaction Observation Station.Combined ground-based data to quantitatively evaluate the applicability of CERES satellite dataset and ERA-5,MERRA2,JRA-55 reanalysis dataset,and finally used ERA-5 data to analyze the characteristics of solar radiation distribution on the black Gobi desert area.The following results are obtained:(1)In 2018,the radiation budget of the Hongliuhe area was mainly downward solar radiation and upward longwave radiation.Upward shortwave radiation was the smallest,and downward shortwave radiation was the largest.The trends of the two were the same.After sunrise,they gradually increased with the increase of the solar elevation angle,the peak value appear at 12 p.m.The maximum value of the downward shortwave radiation is 1104.3 W·m^-2.The upward and downward longwave radiation has the same changing trend,lagging the shortwave radiation by about 1.5 hours,of which the minimum annual average daily difference of the downward shortwave radiation is only 24.68 W·m^-2.The annual variation of the surface albedo in the Hongliuhe area is the highest in December(0.56)and the lowest in August(0.23).On a daily scale,the surface albedo is highest in the morning and evening,and the lowest at noon.The average annual surface albedo in 2018 was 0.29.(2)The sensible heat flux is the largest in May and the smallest in January.The average peak difference between spring and summer is only 3.3 W·m^-2,and the smallest in winter(11.7 W·m^-2).Its peak value of annual average daily change appeared at 13:30(339.4 W·m^-2).The annual average diurnal variation of latent heat flux is basically around 0 W·m^-2.The difference of sensible heat flux between spring and summer is very small(3.31W·m^-2),and the lowest in winter.Affected by precipitation,the latent heat flux in summer is slightly higher than that in spring,autumn and winter,and the average daily peak value in winter is the lowest,only 0.29W·m^-2.The annual variation of latent heat flux and surface soil heat flux is not obvious,and the monthly average annual difference was 21.68 W·m^-2and 25.41W·m^-2,respectively.Net radiation flux and surface soil heat flux were negative at night and reached the highest at 11:30.The seasonal variation of net radiation at Hongliuhe station was summer>spring>autumn>winter.The surface soil heat flux shows the highest in summer and the lowest in winter,with a peak value of 388.75W·m^-2and a valley value of-194.97 W·m^-2.The surface net radiation at Hongliuhe Station was the largest in July and then dropped to the smallest in December.(3)The closure rate of surface energy at Hongliuhe Observation Station is 84%,the closure difference is 16%.The energy distribution in the Gobi area is dominated by sensible heat flux in the daytime,and soil heat flux in the nighttime.The proportion of latent heat flux is relatively small,and the proportion of latent heat flux increases slightly in the daytime,July and September.The momentum flux at Hongliuhe station is small and stable at night,ranging from 0.0002 to 0.85 N·m^-2,rising from 7:00 to about 13:00,reaching the maximum.At the seasonal scale,the momentum flux in summer is slightly larger than that in spring,followed by autumn and winter.Accordingly,the turbulent kinetic energy also shows the same variation characteristics.Wind speed and momentum flux show the same seasonal variation.(4)In general,CERES dataset underestimates shortwave radiation and overestimate longwave radiation,it estimated longwave radiation more accurately than shortwave radiation.The correlation coefficients between ERA-5 and the observed net longwave radiation and net shortwave radiation are 0.92 and 0.91respectively.The correlation coefficients between the MERRA2 reanalysis dataset and the observed net longwave radiation and net shortwave radiation are both 0.88.In general,the JRA-55 dataset overestimates the longwave radiation flux and underestimates the shortwave radiation flux.Comprehensive comparison,the radiant flux estimated by the ERA-5 reanalysis dataset has the highest applicability in the Hongliuhe area.The spatial characteristics of the surface solar radiation on the Hongliu gobi are analyzed through the ERA-5 data,and the surface solar radiation covered by vegetation in the same period is obtained Lower than other areas,urban areas are lower than other areas due to heating in winter.