Superconducting gravimeter and seismometer shedding light on FG5’s offsets, trends and noise: what observations at Onsala Space Observatory can tell us

Hans-Georg Scherneck , Marcin Rajner , Andreas Engfeldt

Abstract

Ten-year worth of absolute gravity (AG) campaigns at Onsala Space Observatory (OSO), Sweden, are simultaneously reduced using synchronous data from a superconducting gravimeter (SG). In this multi-campaign adjustment, the a priori models commonly applied for each setup in AG-alone experiments are sidestepped in favour of SG records and a model to estimate its drift. We obtain a residual (hourly samples) at the 5 nm/s2 RMS level, reducing the SG data with a range of ancillary data for the site’s exposure to ocean and atmospheric loading, and hydrology effects. The target quantity in AG projects in the Baltic Shield area is the secular change of gravity dominated by glacial isostatic adjustment with land uplift as its major part. Investigating into the details of the associated processes using AG requires a long-term stable reference, which is the aim of international comparison campaigns of FG5 instruments. Two of these have been campaigning at OSO since 2009 when the SG had been installed. In the simultaneous inversion of all sixteen campaigns, we identify weaknesses of AG observations, like varying systematic offsets over time, excess microseismic sensitivity, trends in the AG data and side effects on the SG’s scale factor when campaigns are evaluated one by one. The simultaneous adjustment afforded us an SG scale factor very near the result from a campaign with a prototype quantum gravimeter. Whence, we propose that single-campaign results may be biased and conjectures into their variation, let alone its causes misleading. The OSO site appears to present manageable problems as far as environmental influences are concerned. Our findings advocate the use of AG instruments and procedures that are more long-term stable (reference realization), more short-term stable too (setup drifts), less service craving and more resilient to microseismic noise
Author Hans-Georg Scherneck
Hans-Georg Scherneck,,
-
, Marcin Rajner (FGC / CGGA)
Marcin Rajner,,
- Chair of Geodesy and Geodetic Astronomy
, Andreas Engfeldt
Andreas Engfeldt,,
-
Journal seriesJournal of Geodesy, ISSN 0949-7714, e-ISSN 1432-1394
Issue year2020
Vol94
No9
Pages1-15
Publication size in sheets0.7
Keywords in EnglishGravity reference · Absolute gravimetry · Glacial isostatic adjustment · superconducting gravimeter · Onsala Space Observatory
ASJC Classification1903 Computers in Earth Sciences; 1906 Geochemistry and Petrology; 1908 Geophysics
DOIDOI:10.1007/s00190-020-01409-0
Internal identifier21/2020
Languageen angielski
Score (nominal)140
Score sourcejournalList
ScoreMinisterial score = 140.0, 25-08-2020, ArticleFromJournal
Publication indicators Scopus SNIP (Source Normalised Impact per Paper): 2018 = 2.727; WoS Impact Factor: 2018 = 4.528 (2) - 2018=4.494 (5)
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