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

S. C. Han, C. K. Shum, P. Ditmar, A. Braun, Chung-Yen Kuo

Research output: Contribution to journalConference article

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 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.

Original languageEnglish
Pages (from-to)125-130
Number of pages6
JournalEuropean Space Agency, (Special Publication) ESA SP
Issue number569
Publication statusPublished - 2004 Dec 1
EventSecond International GOCE User Workshop: GOCE, The Geoid and Oceanography - Frascati, Italy
Duration: 2004 Mar 82004 Mar 10

Fingerprint

GOCE
gravity field
Gravitation
gravitation
tides
Tides
gravity
oceans
geoid
noise measurement
Earth (planet)
tide
pollution transport
GPS
gravity gradiometers
Global positioning system
wavelength
atmospheres
ocean tide
atmosphere

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science

Cite this

@article{7050750c0689413c8d27c7a0cf300f92,
title = "Effect of high-frequency temporal aliasing on GOCE gravity field solution",
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 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.",
author = "Han, {S. C.} and Shum, {C. K.} and P. Ditmar and A. Braun and Chung-Yen Kuo",
year = "2004",
month = "12",
day = "1",
language = "English",
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journal = "European Space Agency, (Special Publication) ESA SP",
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publisher = "European Space Agency",
number = "569",

}

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

In: European Space Agency, (Special Publication) ESA SP, No. 569, 01.12.2004, p. 125-130.

Research output: Contribution to journalConference article

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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

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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.

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