Evaluation And Fusion Of Multi-source Evapotranspiration Products In The Yellow River Basin And Its Application In Drought

Drought is one of the most frequent and most serious natural disasters in the world,and it has a dramatic impact on human society and the natural environment.And in the context of global warming,the drought has shown an increasing area and aggravated degree,so people around the world are paying more and more attention to drought.Evapotranspiration is a critical process in the hydrological cycle and also plays an important role in energy and carbon cycle.So it can effectively characterize the land water consumption.Therefore,more and more studies have included evapotranspiration into drought research.In this paper,the Yellow River Basin was selected as the research area,and the advantages and disadvantages of the five evapotranspiration products in the study area were first evaluated based on the water balance method.Then,based on the evaluation,the fusion is performed by the Reliability Ensemble Averaging method to obtain a higher quality evapotranspiration product.Finally,a ET-based drought index was calculated based on the fusion product and its applicability in the study area was evaluated.The main research results are as follows:(1)Based on the water balance method,five kinds of evapotranspiration products(GLEAM,GLDAS,E2 O,ZHANG,MERRA_land)in the Yellow River Basin were evaluated.It was found that the performance of each product was quite different.GLEAM is the best comprehensive product,and further analysis found that precipitation was the main forcing data in the region.(2)By using the Reliability Ensemble Averaging method(REA)to fuse five kinds of ET products,we obtained a new long-term data from 1982 to 2009.And we evaluated it through flux tower data and water balance method,and found that its performance in winter and grassland areas was significantly improved,so it was a higher quality evapotranspiration data.(3)The drought index SEDI was calculated by the fusion data and the potential evapotranspiration based on Penman-Monteith.It found that the drought in the Yellow River Basin was mainly concentrated in Shanxi and Gansu from 1982 to 2009.And compared with SPEI and PDSI,SEDI has better applicability in the Yellow River Basin,and it has advantages in agricultural drought and vegetation drought.