Trends In Surface Solar Radiation And Evaluation Of Reanalysis Radiation Datasets From Shule River

The temporal and spatial distribution of solar radiation is the main factor affecting various weather phenomena and global climate change.The long-term variation of solar radiation energy is an important part of current global climate change.Traditional research on the spatio-temporal variation of radiation depends on measured data.In recent years,reanalyzed radiation data is more and more important to atmospheric science.In this study,automatic weather station(AWS)in two different elevation were applied to measure the the downwards surface solar radiation radiation,the upwards surface solar radiation radiation and the net surface solar radiation radiation of the Shule River from 2010 to 2013.The measurements were used for analyzing annual and seasonal variation for the downwards surface solar radiation radiation,the upwards surface solar radiation radiation and the net surface solar radiation radiation.The applicability of the three reanalyzed radiation data in the Shule River Basin was evaluated using measured data.In this paper,the data are analyzed and discussed in combination with meteorological data.The main conclusions are as follows:(1)In the annual scale,there are obvious annual variation of downward short-wave radiation and the net short-wave radiation in the Shule River Basin region,which showing a unimodal shape;the downward short-wave radiation and the net short-wave radiation increase in the first six months and reach a peak.In June-September,there is a small fluctuation in fluctuations,followed by a decrease,which is reduced to a minimum in December or January.In the 4200 m alpine meadow area,the maximum value of the upward short-wave radiation appears in the period of March to May,and the minimum occurs from July to August;the maximum value of the glacial ablation zone appears from June to July,and the minimum occurs in January or December.In the seasonal scale,the season of the alpine meadow is divided into a growing season and a non-growth season,and the the season of melting of the glaciers is divided into a wet season and a dry season.The variation of the three components of the radiation of the 4200 m station fluctuated greatly.The downward short-wave radiation increases in the non-growth season from January to May,and decreases from September to December.The upward short-wave radiation has a tendency to increase first and then decrease in the non-growth season from January to May and from September to December.The net short-wave radiation is basically maintained at a constant rate from January to May,and basically stabilized from September to December.The seasonal variation characteristics of the upward short-wave radiation are not obvious.In the glacial ablation zone,the downward short-wave radiation fluctuations are relatively large,and the upward short-wave radiation season and the net short-wave radiation have little fluctuation in the dry-wet season.Both the downward short-wave radiation and the net short-wave radiation increase from January to May,and decrease from September to December.The upward short-wave radiation season fluctuates in the wet season from January to May and from September to December.(2)The three components of the radiation of the two measured stations present different spatial differences.The 4550 m station has a larger downward-wavelength radiant flux than the 4200 m station,and the upward short-wave radiation is larger,and the net short-wave radiant flux is smaller.The dispersion of short-wave radiation in the alpine meadow area where the 4200 m station is located is significantly larger than that of the glacial ablation zone.(3)in the yearly scale,the three sets of reanalyzed radiation data can better fit the annual variation of the downward short-wave radiation and the net short-wave radiation,but only Har can accurately reflect to the fluctuation of the downward short-wave radiation and net radiation.Overall,ERA-Interim is the most underestimated,followed by CERA-SAT,Har has the smallest degree of bias and the highest accuracy.The accuracy of the three sets of reanalysis data for the upward short-wave radiation is very low.On the seasonal scale,the three sets of reanalyzed radiation data can reflect the variation curves of the short-wave radiation and the net radiation in different seasons and show different degrees of underestimation,but only Har can accurately reflect the daily shock fluctuation of the short-wave radiation.In the fitting of the upward short-wave radiation,the applicability of the three sets of reanalysis data is low.From the perspective of various evaluation indicators,ERA-Interim has the largest deviation,and CERA-SAT secondly has the best Har fitting degree and the highest precision.Overall,Har has the highest accuracy and is the most suitable in the study area.In the spatial scale,the three sets of analysis of the radiation data can basically fit the downward short-wave radiation and the net short-wave radiation.Har is represented by the alpine meadow area represented by the station at 4200 m above sea level and the glaciers represented by the 4550 m elevation station.The accuracy of the ablation zone is the highest,and the applicability of CERA-SAT is second.The accuracy of ERA-Interim is relatively low.Among the two different underlying surfaces,the three sets of reanalysis data are poor in simulating the upward short-wave radiation.The accuracy of the reanalyzed data is slightly better than that of the 4,450 m glacial ablation zone in the 4550 m glacial ablation zone.