Reversion Of Terrestrial Water Storage Variations By Combination Of GPS And GRACE

All features around the world live on water sources,and terrestrial water tightly connect to people's existence.It's a valid way to probe the influence of natural phenomenon and human activities on water source,such as EL Nino,La Nina and manmade factor,as groundwater pumping,irrigation works et al.When terrestrial water storage(TWS)varies,disasters including flood and drought may follow,which may threaten people's security and cause economy damage directly.Hence,it's of greatly scientific and practical significance in research on TWS.Satellite observation methods like Global Positioning System(GPS)and Gravity Recovery and Climate Experiment(GRACE)have been successfully applied in monitoring earth surface geophysical processes.Known as a real-time,high-accuracy,automatic and all-weather measuring access,GPS has been widely used in earth surface displacement monitoring,TWS and also atmosphere loads reversion.GRACE possess the ability to dynamically monitoring worldwide large scale TWS via detecting timevariable gravity field.This dissertation aims on the study of computing TWS by combination of GRACE and GPS,mainly achievements are presented below:Summarize advanced means of TWS reversion by the use of GRACE.Do literature review on the application of GRACE time-variable gravity field in TWS variations,ice melting,sea level rising as well as the methods of combining GRACE and GPS in computing earth surface displacement.Based on GRACE Level-2 products,analyse TWS between 2005 and 2010 of Yangtze River basin,Yellow River basin,Huaihe River basin and Pearl River basin.Meanwhile,using Empirical Orthogonal Function(EOF)to analysis the impact of EL Nino phenomenon on TWS of China.When apply EOF in global TWS,it's found that leakage error in mid-latitude area,Greenland and western America are effectively recovered.Specially,research on leakage error suppression in Amazon basin and China's four basins by Forward Modeling method and scaling factor respectively.Simulate the practical procedures of Modified Ensemble Empirical Mode Decomposition(MEEMD)and compare it with EEMD to reveal its value.At last,an extended means is brought out based on MEEMD.Consequently,with the extended method,the water cycles of the Yangtze,Yellow,Huaihe and the Pearl river basins are proven to be 3.05,2.37,2.37,2.13 years,respectively.Finally,GPS observations are applied to reveal Sichuan region surface movements,with GRACE derived displacements to confirm the annual terms in Sichuan GPS sites vertical displacements time series is the consequence of seasonal TWS.found,geometry and climate effects may responsible for the phase delay in GPS vertical displacements time series and TWS.