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Differences of geoid height anomalies of atmosphere-removed and hydrospheric models, as a function of the spherical harmonic degree l. The largest signal produced by the NIB-removed minus hydrosphere case (filled diamond). Similarly the hydrosphere was also subtracted from the intermediate atmosphere removed models. These are indicated with squares for the basin models (filled – 2000, blank – 500) and with triangles for the shallow water models (filled – 2000, blank – 500).
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The forthcoming Gravity Recovery and Climate Experience (GRACE) gravity satellite will detect seasonal variations of the gravity field with very high accuracy. Seasonal variations of the mass redistribution would be useful data for several disciplines of geophysics and geodesy, if the seasonal mass variation could be unequivocally separated into it...
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... to the degree geoid height anomaly spectra in Fig. 1, that of the atmosphere removed models were computed by (3). These models describe several models for the 'recovered' hydrospheric gravity. Therefore, their differences with the 'real' hydrospheric gravity describe the atmospheric correction errors, and are shown in Fig. ...
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Water pixel extraction and correction of the atmospheric signal represent prerequisite steps prior to applying algorithms dedicated to the assessment of water quality of natural surface water bodies. The recent multiplication of medium spatial resolution sensors (10–60 m) provides the required constellation to monitoring bio-optical and biogeochemi...
Citations
... Bár a különböző idő-szakokra számított GRACE modellekből már időszakos (szezonális) változások szépen kimutathatók, a GRACE még így is egy nagyságrenddel elmaradt a tervezett pontosságától. A 9. ábrán az a priori modellezett GRACE mérési hibát [FÖLDVÁRY, FUKUDA 2002] az a posteriori eredménnyel, a GRACE mérésekből számított szezonális modellek becsült hibáival, azaz a CSR havi geopotenciálmodelljeinek szórásaival [TAPLEY et al. 2004] vetjük össze. Megjegyzendő, hogy a CSR (Center for Space Research, University of Texas, Austin) által kibocsátott geopotenciálmodellek 2003 után nagyobb megbízhatóságúak, mint 2003 előtt, aminek az oka a számítás során felhasznált modellek (óceánmodell és atmoszféramodell) pontossági különbségeiben rejlik. ...
The scientific sensation of this decade in geodesy is the launch of gravity satellites. Three missions have been and/or are planned to be launched. These are the CHAMP (CHAllenging Mini-satellite Payload), a High-Low SST (Satellite-to-satellite) mission, which has been launched in 2000, the GRACE (Gravity Recovery And Climate Experiment), a Low-Low SST pair satellite, which has been launched in 2002, and finally the GOCE (Gravity field and steady-state Ocean Circulation Explorer) gradiometry satellite will be launched in 2006. What results are provided by these satellites for the geoscience? What further improvements can be expected? What can be a follow-on of these missions? What should space gravimetry focus on after them? An introduction of the three missions, their prospective results and their effect on geodesy are discussed in this paper.
We tried to model an artificial geoid signal and than decompose it into its causes. First we modeled the geoid heights changes caused by the hydrosphere and the atmosphere, and composed them to simulate the measurable signals by GRACE. Then, we decomposed the signals by considering the following properties; 1) different ocean responses to atmospheric pressure changes, and 2) different time-frequencies of the variations of the hydrospheric contributors. These tests prove that an appropriate assumption for the ocean response is important to minimize decomposition errors. Since atmospheric errors necessarily affect the recovered hydrospheric signal, minimization of these errors by mathematical tricks is desired.
