Terrestrial Gravity Fluctuations
Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been d...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2015-12-01
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| Series: | Living Reviews in Relativity |
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| Online Access: | http://www.livingreviews.org/lrr-2015-3 |
| _version_ | 1818960327178452992 |
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| author | Jan Harms |
| author_facet | Jan Harms |
| author_sort | Jan Harms |
| collection | DOAJ |
| description | Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article. |
| first_indexed | 2024-12-20T11:55:46Z |
| format | Article |
| id | doaj.art-e7eb80a9f3014fbb8b38a3a5ddb6d6d9 |
| institution | Directory Open Access Journal |
| issn | 1433-8351 |
| language | English |
| last_indexed | 2024-12-20T11:55:46Z |
| publishDate | 2015-12-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Living Reviews in Relativity |
| spelling | doaj.art-e7eb80a9f3014fbb8b38a3a5ddb6d6d92022-12-21T19:41:39ZengSpringerOpenLiving Reviews in Relativity1433-83512015-12-0118310.1007/lrr-2015-3lrr-2015-3Terrestrial Gravity FluctuationsJan Harms0Università degli Studi di Urbino ‘Carlo Bo’, 61029 Urbino, ItalyDifferent forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.http://www.livingreviews.org/lrr-2015-3Wiener filterTerrestrial gravityMitigationNewtonian noise |
| spellingShingle | Jan Harms Terrestrial Gravity Fluctuations Living Reviews in Relativity Wiener filter Terrestrial gravity Mitigation Newtonian noise |
| title | Terrestrial Gravity Fluctuations |
| title_full | Terrestrial Gravity Fluctuations |
| title_fullStr | Terrestrial Gravity Fluctuations |
| title_full_unstemmed | Terrestrial Gravity Fluctuations |
| title_short | Terrestrial Gravity Fluctuations |
| title_sort | terrestrial gravity fluctuations |
| topic | Wiener filter Terrestrial gravity Mitigation Newtonian noise |
| url | http://www.livingreviews.org/lrr-2015-3 |
| work_keys_str_mv | AT janharms terrestrialgravityfluctuations |