Precise definition of the effective measurement height of free-fall absolute gravimeters
- verfasst von
- Ludger Timmen
- Abstract
For up-to-date absolute gravimeters, the trajectory of the test mass during a free-fall experiment (drop) is about 20 cm along the vertical, and the corresponding gravity change is about 60 × 10-8 m s-2. The reference height of the derived free-fall acceleration g has to be defined with an accuracy of 1 mm to 2 mm within the dropping distance to preserve the accuracy of the measurement system (e.g. FG5: 1 × 10-8 m s-2 to 2 × 10-8 m s-2). The equation of motion comprises a vertical gravity gradient to take the height dependence of g into account. In general, a linear vertical gravity gradient γ is introduced that has been measured by relative gravimeters. In that case, the g-value refers to the origin of the coordinate system (z = 0), which is normally the starting position of the drop. In the case of an unknown or uncertain gradient we recommend an alternative approach. A simple parabolic equation (assumption γ = 0) can be used to evaluate the time/distance data pairs, and later these g-determinations have to be corrected for the vertical gravity gradient using the effective measurement height. The solution presented is not restricted to low initial velocities. It considers time/distance measurements equally spaced in distance. Also, in extreme cases, unknown non-linearities within the vertical gravity gradient do not significantly affect the result of the absolute gravity determination.
- Organisationseinheit(en)
-
Institut für Erdmessung
- Typ
- Artikel
- Journal
- METROLOGIA
- Band
- 40
- Seiten
- 62-65
- Anzahl der Seiten
- 4
- ISSN
- 0026-1394
- Publikationsdatum
- 01.04.2003
- Publikationsstatus
- Veröffentlicht
- Peer-reviewed
- Ja
- ASJC Scopus Sachgebiete
- Ingenieurwesen (insg.)
- Elektronische Version(en)
-
https://doi.org/10.1088/0026-1394/40/2/310 (Zugang:
Geschlossen)
