Research On Hydrologic Evaluation Of TRMM Multi-satellite Precipitation Analysis Over Nanliujiang Basin

With the rapid development of the satellite technology,the TRMM(Tropical Rainfall Measuring Mission)multi-satellite precipitation are widely used in the hydrology and meteorology depending on the advantage of its more reasonable spatio-temporal distribution.However,more and more people pay close attention to the accuracy of the TRMM multi-satellite precipitation datasets and that how to effectively utilize the advantages of satellite precipitation data.In this paper,the area controlled by the Changle hydrologic station in the upper Nanliujiang River Basin was selected as the study area.First,the Version-7 TRMM Multisatellite Precipitation Analysis(TMPA)products including near-real-time products(3B42RTV7)and post-real-time research products(3B42V7)from June 2007 to December 2016 were assessed via comparison with the rain gauge observations,which involves daily,monthly and seasonal temporal scales.Then,these two TRMM multi-satellite precipitation datasets were applied to drive the lumped Xin'anjiang hydrologic model to perform stream flow simulation.Last,this paper develops a merged precipitation methods about the TRMM3B42V7 precipitation and the rain gauge observations to improve the modeling performance,under conditions of combining the respective advantages of the rain gauge observations and the TRMM multi-satellite precipitation.The accuracy of TRMM3B42V7 and TRMM3B42RTV7 multi-satellite precipitation in Nanliujiang River Basin is evaluated in the view of the point and surface respectively.The results show that at daily scale,there is an overestimation of rainfall between the two TRMM multi-satellite rainfall products,and the relative bias of daily rainfall is about 5%,and specially point out that there are regional differences in the basin.The accuracy of the TRMM3B42V7 rainfall product is better than that of the TRMM3B42RTV7 as a whole,and with the increase of time scale,the accuracy of the satellite product is improved.The accuracy of the satellite-based daily rainfall product in the small rainfall events less than 1 mm and the heavy rainfall events greater than 30 mm is poor.In summary,there is some error in TRMM3B42V7 rainfall product,but it still has application value in areas lacking rainfall data.By using the TRMM multi-satellite precipitation to drive the Xin'anjiang hydrologic model,it was found that the trends of the simulated runoff curves process based on the rain gauge observations,TRMM3B42RTV7,and TRMM3B42V7 satellite rainfall data are generally consistent with that of the observed runoff curve process.The daily runoff simulation results of TRMM3B42V7 on the daily scale had a high Nash-Sutcliffe index(NSCE,0.70),and the correlation coefficient is 0.89,which is better than the TRMM3B42RTV7 rainfall product in terms of simulated runoff.With the increase of time scale,the runoff simulation accuracy is significantly improved.TRMM3B42V7 rainfall products have good application prospects in hydrological simulation and water resources management.Based on the Thiesen polygon,the advantages of spatial distribution of TRMM3B42V7 grid rainfall data were merged into the rain gauge observations,and Daily runoff simulation with Xin'anjiang hydrologic model using this rainfall data of fusion as input shows that:the trends of the simulated runoff curves process based on the rainfall data of fusion were further more consistent with that of the reference runoff curve process,and the simulated runoff had a higher Nash-Sutcliffe index(NSCE,0.90),and the correlation coefficient is 0.96.With the increase of time scale,the Nash-Sutcliffe index of the simulated runoff is significantly improved.In summary,the merged precipitation methods of this paper can be used to runoff simulation over Nanliujiang River Basin.At the same time,the merged precipitation datasets provides a more accurate source of rainfall data for the lumped Xin'anjiang model.