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POSITIONING DATA – FOR SOCIETY’S BENEFIT

DETERMINATION OF THE GRAVITY FIELD OVER NORWEGIAN TERRITORIES. POSITIONING DATA – FOR SOCIETY’S BENEFIT. GRAVNOR: DETERMINATION OF THE GRAVITY FIELD OVER NORWEGIAN TERRITORIES USING GOCE DATA AND SPACE GEODESY SOFTWARE GEOSAT E. Mysen (Norwegian Mapping Authority, NMA)

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POSITIONING DATA – FOR SOCIETY’S BENEFIT

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  1. DETERMINATION OF THE GRAVITY FIELD OVER NORWEGIAN TERRITORIES POSITIONING DATA – FOR SOCIETY’S BENEFIT

  2. GRAVNOR: DETERMINATION OF THE GRAVITY FIELD OVER NORWEGIAN TERRITORIES USING GOCE DATA AND SPACE GEODESY SOFTWARE GEOSAT E. Mysen (Norwegian Mapping Authority, NMA) P.H. Andersen (Norwegian Defence Research Establishment, NDRE) POSITIONING DATA – FOR SOCIETY’S BENEFIT

  3. SPACE GEODESY SOFTWARE GEOSAT • 25 years at Norwegian Defence Research Establishment • GPS, VLBI, SLR simultaneously at observation level • Inter technique calibration • Stochastic parameter evolution between days (arcs) • Utilization of parameter statistics • Accelerometry: GOCE POSITIONING DATA – FOR SOCIETY’S BENEFIT

  4. DETERMINATION OF LOCAL GRAVITY (NORWAY) • Norwegian Mapping Authority (NMA): • Contribute to the determination of climate parameters • Determine the cm geoid • Transfer of GEOSAT competence from NDRE to NMA • Why local analysis? • ESA -> SH expansion: truncation issues (40,000 parameters) • May still be information left in accelerometer signal • Norway gravitationally “rough” POSITIONING DATA – FOR SOCIETY’S BENEFIT

  5. STRATEGY POSITIONING DATA – FOR SOCIETY’S BENEFIT

  6. SINGLE ACCELEROMETER OBSERVATIONS • Benefits: • Less susceptible to accelerometer failure • Algorithms applicable to other missions like GRACE • Disadvantage: • Non-gravitational force has to be modeled as part of gravity field determination POSITIONING DATA – FOR SOCIETY’S BENEFIT

  7. ACCELEROMETER OBSERVATION EQUATION Output of accelerometer j: True acceleration: POSITIONING DATA – FOR SOCIETY’S BENEFIT

  8. ATTITUDE CORRECTIONS GRF 2 CRF rotation matrix: Indirect effect on true acceleration: : POSITIONING DATA – FOR SOCIETY’S BENEFIT

  9. DYNAMIC ORBIT DETERMINATION/CALIBRATION Computation of orbit: Accelerometer orbit-GPS orbit=instrument imperfections Expression for non-gravitational force D dependent instrument imperfections? POSITIONING DATA – FOR SOCIETY’S BENEFIT

  10. Estimate of D for Dynamic Orbit Determination LSQ applied to accelerometer observations with D as only unknown: POSITIONING DATA – FOR SOCIETY’S BENEFIT

  11. CALIBRATION BY DOD • Issue: Along-track scale factor not well determined from DOD alone due to along-track DFC (Visser, 2009) • Solution?: Simultaneous determination of orbit and local gravity field POSITIONING DATA – FOR SOCIETY’S BENEFIT

  12. PARALLELL AND FUTURE • Altimetry: Sea level & ocean currents (NMA) • GRACE • WEAKNESSES OF GRAVNOR??? POSITIONING DATA – FOR SOCIETY’S BENEFIT

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