Combined GRACE And GPS To Study Terrestrial Water Storage

The GRACE?Gravity Recovery and Climate Experiment?satellite has been working for 15 years since it was launched in 2002,which provided us with a large number of previous scientific observation data.It has made a great contribution to the study of the earth's gravitational field,especially in the establishment of middle wave length,static gravitational field,the change of surface quality terrestrial water storage,glaciers,ocean,co-seismic deformation and the loading deformation included as well.The change of terrestrial water storage result from Earth's gravity field changing,and this can be detected by GRACE.Through the time-varying gravity field provided by GRACE satellite,large-scale water reserves change can be reversed by the terrestrial hydrological signal.Combined with hydrological model,Changes in groundwater can detected.This provides a new method for the research and management of regional water resources,and can also provide a reference for the study of ground subsidence caused by groundwater exploitation.In this paper,the GRACE gravity field model is used to study the characteristics of regional terrestrial hydrological information,and the method combining GPS observation deformation data to recover region terrestrial water storage signal is testing.The main contents are as follows:?1?The research status and key technologies which use the GRACE gravitational field as the model coefficient to inversion terrestrial water storage are summarized in detail.The parameter settings of the classical filtering method are estimated.According to the data of RL₀5,and the principle of using gravity felid model to retrieve surface quality change and ground load deformation formula is deduced.By testing the different parameters in the process of post-processing and following the classical filtering method based on the GRACE gravity field model GSM data,we have offered some suggestions.This essay introduces the author's idea to recover regional hydrological signals by adding additional timing constraints related to GPS.?2?Due to the process of the gravity field model inversion exists problems such as high order truncation,filter,leakage error.We put forward the new algorithm,"additional GPS timing constraints to restore regional hydrological signal".Comparing with the gravity field model of ground surface deformation and load of GPS deformation by the spectrum analysis method,we obtained the signal loss,and based on the deformation ratio can restore the real signal of the quality changes.?3?Using GRACE gravity field model CSR_RL05 data to retrieve the typical North China regional groundwater dynamic change serious groundwater exploitation.Comparing the dynamic change characteristics of the regional groundwater,land surface water and terrestrial water storage show that the variation of surface water in North China is relatively slight,variation period stability,and the change of terrestrial water storage is mainly due to the change of the groundwater;From 2002 to 2016,terrestrial water storage lost with a rate of 37.32mm/a in the North China Plain.Combined with the hydrological model data,groundwater loss rate is about 34.6±3.2 mm/a,and water loss is about 66.05 billion tons.?4?By researching the GRACE gravity field model data,GLADS hydrological model data and the PBO?Plate Boundary Observation?monitoring network GPS deformation information,this essay concludes the experiment about the additional GPS timing constraints method,which also detects the dynamic changes of the Central Valley of California groundwater.Research shows that California's Central Valley Regional terrestrial water storage present descent trend whole.The change of surface water changes showed stable state but decreased slightly during the long period,similar to terrestrial water storage.From 2003 to 2015,California's Central Valley groundwater loss rate is about 16.43±1.98mm/a,the results show the consistency with previous research,and to verify the feasibility of the additional GPS timing constraint method.