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Study On Pre-processing Of GOCE Satellite Gravity Gradiometry Data

Posted on:2011-08-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y L WuFull Text:PDF
GTID:1100330332982967Subject:Solid Earth Physics
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THE EARTH'S gravity field is always one of the main tasks of modern geodesy research field. With the breakthrough of satellite gravimetry technique, the Satellite-to-Satellite Tracing (SST) and Satellite Gravity Gradiometry (SGG) are regarded as the most effective techniques for the determination of the earth's gravity field and its temporal variation with high accuracy and high resolution. As GOCE satellite successfully launched on 17th March 2009, theory and methodology of gravity field recovery using Satellite Gravity Gradiometry data become a hot issue in international geodesy research field. The satellite gradiometry data pre-processing in high quality can provide pure data for recovering static earth's gracity field model with high accuracy, which is a key link in satellite gradiometry data process and application. Study on pre-processing of GOCE satellite gradiometry data is one of the key tasks to achieve the scientific goals of GOCE mission. Under the background of the scientific research, keeping the pace with the development of the satellite gravity gradiometry technique, the theory and methodology of pre-processing of GOCE satellite gradiometry data are studied in this dissertation, including temporal gravity field correction, outliers detection and external calibration on GOCE data. The corresponding GOCE data pre-processing software with autonomous copyright are developed, which has scientific significance and can be applicated to develop our own satellite gravity gradiometry technique.The main research work and contributions of this dissertation are as follow:THE milestone and current status of satellite gravimetry technique is reviewed in detail. The theory and methodology for the determination of the earth's gravity field base on satellite gravity gradiometry technique, pre-processing of GOCE satellite gradiometry data and related research progress home and abroad are summarizedFUNDAMENTAL theories of the satellite gradiometry are researched. The satellite gradient observation equations are derived in detail. Then time reference system and coordinate reference frame related to GOCE satellite and the corresponding transformations are introduced. And the gravity gradient tensor transformations between different coordinate system are derived. The GOCE satellite mission is comprehensively reviewed, including scientific objectives, technique characteristics, satellite system components, data product and its classification etc. The error properties of satellite gradiometry data and precise orbit determination are analysed.TIDAL effects among temporal gravity field correction in GOCE satellite gradiometry data are deeply studied, including the effect of astronomical tides, solid earth tides, ocean tides and pole tides on satellite gradiometry data. And tidal effect corrections for satellite gradiometry data are derived. The results indicate that total tidal effect is 10-3E in order, close to GOCE measurement accuracy. Considering the systemanic of tidal effect, it should be removed as colored noise in GOCE data pre-processing.(?)ON-TIDAL effects on GOCE gravity gradiometry observation are discussed, including atmospheric and oceanic high-frequency mass variations, land hydrology. The corresponding correction models are derived. It can be indicated that the effect of atmospheric and oceanic high-frequency mass variations, land hydrology are 2 degrees lower in order than GOCE measurement accuracy.THEORY and methodology of outlier detection for satellite gradiometry data are deeply stuied, including Threshold method, Grubbs's test, Dixon test, wavelet analysis method. Practical numerical models of ech method are derived. The computation results using satellite gradiometry data with noise and different types of outliers indicate that statistics method, which is easy and fast, can detec innovative outlier with a rather high outlier ratio of success. The statistics method can be applied to quick-look outlier detection. Wavelet method is valid for all three outlier distribution types, with a high outlier ratio of success and low outlier ratio of failure.BASE on wavelet shrinkage denoising method and Dixon test, combined algorithm foroutlier detection is presented. The computation result indicates that combined method shows best performance than the other outlier detection methods, with successful detection of nearly all the innovative outliers and most bulk outliers. It is suggested to apply the combined method for pre-processing of satellite gradiometry dataMETHODOLOGY of external calibration of gradiometry observations using global-gravity models, regional terrestrial gravity data and high-low SST data are deeply stuied. The computation results indicate that it can achieve relative accuracy at 10-4 order to calibrate scale factor and bias base on high accuracy earth's gravity model. The relative accuracy of calibration on scale factor base on regional terrestrial gravity data can achieve 10"2 order.GOCE satellite gradiometry data processing scheme are studied, L1b data pre-processing flow is presented. GOCE satellite gradiometry data pre-processing software is developed independently, with the functions as temporal gravity field correction, outlier detection and external calibration.
Keywords/Search Tags:Earth's gravity model, GOCE, Satellite Gravity Gradiometry, Pre-processing, Outlier Detection, Wavelet Analysis, Tidal Effect, External Calibration
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