### Abstract

European Space Agency's Gravity field and steady state Ocean Circulation Explorer (GOCE) space gravity gradiometer (SGG) mission is anticipated to determine the mean gravity field of the Earth with an unprecedented geoid accuracy of several cm rms with wavelength of 130 km or longer. In a sun-synchronous, near-polar, circular orbit at an altitude of 250 km, GOCE senses not only static gravitational forces but also tides and other temporal signals resulting from mass variations of various Earth processes. These signals manifest as gravity field changes and include effects such as atmospheric loading on the Earth, ground water movement, oceanic mass variations, and ice mass flux changes. In this study, we investigate the high (temporal) frequency aliasing and mismodeling effects from ocean tides, atmosphere, and hydrological mass variations on the GOCE estimated gravity model complete to degree (N _{max}) 300 using simulated diagonal gravity gradient tensor measurements over a 2 month data span, applying frequency-dependent noise while ignoring the high-low GPS tracking data. Various mass variation effects have been computed for N_{max}=60. It is concluded that the power spectral density (PSD) of the considered temporal mass variations generally has less magnitude than the measurements noise over all spectral bands. Only unmodeled total ocean tidal signals are found to have errors of a few mE/Hz^{1/2} maximum within the measurement bandwidth. Specifically, S_{2} and K _{1} tides are significant for N_{max}≤90, while atmosphere and hydrological affects are significantly less on the two-month GOCE mean gravity solution. The measurement noise and regularization show ∼15 cm RMS geoid error for a spatial scale 67 km or longer, and error due to other temporal mass variations is an order of magnitude smaller at 1-2 cm RMS. Future simulation studies include further assessment of GOCE gravity field errors at long wavelength components when high-low GPS tracking is included and for the cases of tidal perturbations at spatial frequencies shorter than N _{max}=60.

Original language | English |
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Pages (from-to) | 125-130 |

Number of pages | 6 |

Journal | European Space Agency, (Special Publication) ESA SP |

Issue number | 569 |

Publication status | Published - 2004 Dec 1 |

Event | Second International GOCE User Workshop: GOCE, The Geoid and Oceanography - Frascati, Italy Duration: 2004 Mar 8 → 2004 Mar 10 |

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### All Science Journal Classification (ASJC) codes

- Aerospace Engineering
- Space and Planetary Science

### Cite this

*European Space Agency, (Special Publication) ESA SP*, (569), 125-130.

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*European Space Agency, (Special Publication) ESA SP*, no. 569, pp. 125-130.

**Effect of high-frequency temporal aliasing on GOCE gravity field solution.** / Han, S. C.; Shum, C. K.; Ditmar, P.; Braun, A.; Kuo, Chung-Yen.

Research output: Contribution to journal › Conference article

TY - JOUR

T1 - Effect of high-frequency temporal aliasing on GOCE gravity field solution

AU - Han, S. C.

AU - Shum, C. K.

AU - Ditmar, P.

AU - Braun, A.

AU - Kuo, Chung-Yen

PY - 2004/12/1

Y1 - 2004/12/1

N2 - European Space Agency's Gravity field and steady state Ocean Circulation Explorer (GOCE) space gravity gradiometer (SGG) mission is anticipated to determine the mean gravity field of the Earth with an unprecedented geoid accuracy of several cm rms with wavelength of 130 km or longer. In a sun-synchronous, near-polar, circular orbit at an altitude of 250 km, GOCE senses not only static gravitational forces but also tides and other temporal signals resulting from mass variations of various Earth processes. These signals manifest as gravity field changes and include effects such as atmospheric loading on the Earth, ground water movement, oceanic mass variations, and ice mass flux changes. In this study, we investigate the high (temporal) frequency aliasing and mismodeling effects from ocean tides, atmosphere, and hydrological mass variations on the GOCE estimated gravity model complete to degree (N max) 300 using simulated diagonal gravity gradient tensor measurements over a 2 month data span, applying frequency-dependent noise while ignoring the high-low GPS tracking data. Various mass variation effects have been computed for Nmax=60. It is concluded that the power spectral density (PSD) of the considered temporal mass variations generally has less magnitude than the measurements noise over all spectral bands. Only unmodeled total ocean tidal signals are found to have errors of a few mE/Hz1/2 maximum within the measurement bandwidth. Specifically, S2 and K 1 tides are significant for Nmax≤90, while atmosphere and hydrological affects are significantly less on the two-month GOCE mean gravity solution. The measurement noise and regularization show ∼15 cm RMS geoid error for a spatial scale 67 km or longer, and error due to other temporal mass variations is an order of magnitude smaller at 1-2 cm RMS. Future simulation studies include further assessment of GOCE gravity field errors at long wavelength components when high-low GPS tracking is included and for the cases of tidal perturbations at spatial frequencies shorter than N max=60.

AB - European Space Agency's Gravity field and steady state Ocean Circulation Explorer (GOCE) space gravity gradiometer (SGG) mission is anticipated to determine the mean gravity field of the Earth with an unprecedented geoid accuracy of several cm rms with wavelength of 130 km or longer. In a sun-synchronous, near-polar, circular orbit at an altitude of 250 km, GOCE senses not only static gravitational forces but also tides and other temporal signals resulting from mass variations of various Earth processes. These signals manifest as gravity field changes and include effects such as atmospheric loading on the Earth, ground water movement, oceanic mass variations, and ice mass flux changes. In this study, we investigate the high (temporal) frequency aliasing and mismodeling effects from ocean tides, atmosphere, and hydrological mass variations on the GOCE estimated gravity model complete to degree (N max) 300 using simulated diagonal gravity gradient tensor measurements over a 2 month data span, applying frequency-dependent noise while ignoring the high-low GPS tracking data. Various mass variation effects have been computed for Nmax=60. It is concluded that the power spectral density (PSD) of the considered temporal mass variations generally has less magnitude than the measurements noise over all spectral bands. Only unmodeled total ocean tidal signals are found to have errors of a few mE/Hz1/2 maximum within the measurement bandwidth. Specifically, S2 and K 1 tides are significant for Nmax≤90, while atmosphere and hydrological affects are significantly less on the two-month GOCE mean gravity solution. The measurement noise and regularization show ∼15 cm RMS geoid error for a spatial scale 67 km or longer, and error due to other temporal mass variations is an order of magnitude smaller at 1-2 cm RMS. Future simulation studies include further assessment of GOCE gravity field errors at long wavelength components when high-low GPS tracking is included and for the cases of tidal perturbations at spatial frequencies shorter than N max=60.

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M3 - Conference article

SP - 125

EP - 130

JO - European Space Agency, (Special Publication) ESA SP

JF - European Space Agency, (Special Publication) ESA SP

SN - 0379-6566

IS - 569

ER -