| Surface radiation balance parameters are important in radiation balance,energy budget,water cycle and other researches.As the“roof of the world”,the“Asian water tower”and the“third pole region”,the Tibetan Plateau has an extremely important influence on the peri-third pole surrounding area and even the whole world.At present,there are several problems of radiation balance parameters of the Tibetan Plateau,such as lower spatial and temporal resolutions,lack of pertinence,and lack of systematic verification of existing data.This research selected surface air temperature(T_a),downward longwave radiation(DLR),upward longwave radiation(ULR),downward shortwave radiation(DSR),Upward shortwave radiation(DSR),and upward shortwave radiation(USR)as examples,to investigate surface radiation balance parameters in the Tibetan Plateau.Most of the current T_a datasets of reanalysis products have limitations at local scales due to their coarse spatial resolutions.This research proposes a practical method for T_a downscaling based on the digital elevation model.This method is applied to downscale T_a of the China regional surface meteorological feature dataset(CRSMFD)at 0.1°and the EAR-interim(EARI)product at 0.125°to 0.01°.The downscaled T_a is evaluated from the perspectives of accuracy and image quality.Results showed that the RMSE of daily mean T_a downscaled from the CRSMFD product was 1.13±1.0K at 105 meteorological stations,and RMSEs calculated based on data from three experimental stations ranged from 0.96K to 2.34K;the instantaneous T_a downscaled from CRSMFD had RMSEs of1.02K to 4.0K at the three experimental stations.T_a after downscaling had better agreement with the ground measured T_a than before downscaling.Before and after downscaling,ERAI had large errors in Tibetan Plateau.The accurate estimation of the all-weather DLR with a high temporal resolution is important for the estimation of the surface net radiation and evapotranspiration.To obtain an in-depth understanding of the performances of different models in the estimation of the DLR over the Tibetan Plateau,this research tested eight methods under clear-sky conditions and six methods under cloudy conditions based on ground-measured data.The results illustrated that the Dilley and O'Brien and the Lhomme et al.methods are most suitable for under clear-sky conditions and cloudy conditions,respectively.With the combined all-weather DLR model,the hourly all-weather daytime DLR dataset with a spatial resolution of 0.0625°from 2008 to 2016 over the Tibetan Plateau was generated.The results showed that average RMSE of the estimated DLR was approximately26.4W/m~2.Based on the estimation results of DLR,the ULR of the Tibetan Plateau from2008 to 2016 was estimated.The verification results indicated that the average RMSE is28.7W/m~2.Surface shortwave radiation contains DSR and USR.This research firstly verified the DSR of CLDAS and China's high-resolution surface solar radiation datasets over China(HSSSR).CLDAS has less uncertainty in clear-sky conditions with an average RMSE of less than 80.0W/m~2.Under cloudy conditions,CLADS has better accuracy than HRSSR in the Tibetan Plateau,and its average RMSE is less than 200W/m~2.This research estimated the USR based on CLDAS and surface albedo products.The estimated USR has a greater uncertainty,mainly due to the overestimation of the DSR data itself.Based on the estimation results of DLR,ULR,DSR,and USR,this research estimated the net radiation(NR).The verification results show that the error range is from75.4W/m~2 to 166.7W/m~2,and the estimation results at individual sites have large errors.The method of estimating the respective radiation components and integrating them to obtain NR has a larger uncertainty.In this paper,a series of radiation balance parameters such as T_a,DLR,ULR,DSR,and USR are optimized and estimated.Then,corresponding data are generated.The study results provide important parameters for the study of energy budget and water cycle in the Tibetan Plateau. |
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