Abstract
Traceability is a feature that is required more frequently in local geodetic high-precision measurements. This basic term of metrology, a measurement science, describes the property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty (BIPM International vocabulary of metrology – basic and general concepts and associated terms (VIM). JCGM 200:2008. Joint Committee for Guides in Metrology, 2008b).
GPS measurements are widely used in local geodynamical research. From the viewpoint of metrology, their traceability is uncontrollable because the scale cannot be unambiguously conducted based on the definition of the metre. In particular, atmospheric effects on a GPS signal cannot be modelled or calibrated along the path of the signal.
We are testing a method to bring the traceable scale to small GPS networks using high-precision electronic distance measurement (EDM) instruments, the scales of which have been corrected and validated in calibrations at the Nummela Standard Baseline. The traceable scale of EDM is expected to explain the annual scale variations that have been found in GPS time series and to improve results of episodic GPS campaigns.
The scale of a standard baseline is validated and maintained through regular interference measurements with the Väisälä interference comparator, in which a quartz gauge conveys the traceable scale. The results from the interference measurements in 2005 and 2007 in Nummela are presented here together with a brief description of the present state of the renowned measurement standard. A standard uncertainty of ±0.08 ppm was obtained again for the baseline length of 864 m, and the results confirm the good long-term stability of the baseline. The scale is transferred further to geodetic and geophysical applications by using calibrated high-precision EDM instruments as transfer standards.
Local geodynamical measurements will profit from the reduced and accurately estimated uncertainty of the measurement, and therefore we seek further innovations to improve their traceability. We present here a topical example of calibrations and scale transfer for a baseline and monitoring network around a nuclear power plant. We compare simultaneously measured EDM and GPS results and show a scale bias of approximately 1 ppm between them. By using a traceable length in the network, the bias could be reduced, e.g. by improving the processing strategy of GPS observations. This paper focuses on the metrological part of EDM. Some related results and analysis of GPS measurements are discussed in another paper in this volume (Koivula et al. GPS metrology – bringing traceable scale to local crustal deformation GPS network. IAG Scientific Assembly “Geodesy for Planet Earth”, Buenos Aires, Argentina, 2010).
Keywords
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsReferences
BIPM (2008a) Evaluation of measurement data – guide to the expression of uncertainty in measurement (GUM). JCGM 100:2008. Joint Committee for Guides in Metrology. http://www.bipm.org/
BIPM (2008b) International vocabulary of metrology – basic and general concepts and associated terms (VIM). JCGM 200:2008. Joint Committee for Guides in Metrology. http://www.bipm.org/
Chen R, Kakkuri J (1995) GPS Work at Olkiluoto for the Year of 1994. Work Report PATU-95-30e, Teollisuuden Voima Oy. Helsinki, p 11
Chen R, Kakkuri J (1996) GPS Operations at Olkiluoto, Kivetty, and Romuvaara in 1995. Work report PATU-96-07e, Posiva Oy. Helsinki, p 68
IAG (1999) IAG Resolutions adopted at the XXIIth General Assembly in Birmingham, 1999. http://www.gfy.ku.dk/~iag/HB2000/part2/iag_res.htm
Jokela J, Häkli P (2010) Interference measurements of the Nummela Standard Baseline in 2005 and 2007. Publications of the Finnish Geodetic Institute, no 144, p 85
Jokela J, Poutanen M (1998). Väisälä baselines in Finland. Publications of the Finnish Geodetic Institute, no 127, p 61
Jokela J, Häkli P, Ahola J, Būga A, Putrimas R (2009) On traceability of long distances. XIX IMEKO World Congress Fundamental and Applied Metrology, Lisbon, Portugal, pp 1882–1887, 6–11 Sept 2009. http://www.imeko2009.it.pt/Papers/FP_100.pdf
Kallio U, Poutanen M (2011) Can we really promise a mm-accuracy for the local ties on a geo-VLBI antenna? (Scientific Assembly “Geodesy for Planet Earth”, Buenos Aires, Argentina, Aug 31–Sept 4)
Kallio U, Ahola J, Koivula H, Jokela J., Poutanen M (2009) GPS operations at Olkiluoto, Kivetty and Romuvaara in 2008. Working Report 2009–75. Posiva, Olkiluoto, p 216. http://www.posiva.fi/en/databank/working_reports
Koivula H, Häkli P, Jokela J, Buga A., Putrimas R (2011) GPS metrology – bringing traceable scale to local crustal deformation GPS network. (IAG Scientific Assembly “Geodesy for Planet Earth”, Buenos Aires, Argentina, Aug 31–Sept 4)
Lassila A,. Jokela J, Poutanen M, Xu J (2003) Absolute calibration of quartz bars of Väisälä interferometer by white light gauge block interferometer. XVII IMEKO World Congress, Dubrovnik, Croatia, pp 1886–1889, 22–27 June 2003. http://www.imeko.org/publications/wc-2003/PWC-2003-TC14-026.pdf
Ollikainen M, Ahola J, Koivula H (2004). GPS operations at Olkiluoto, Kivetty and Romuvaara in 2002–2003. Working Report 2004–12. Posiva, Olkiluoto, p 268. http://www.posiva.fi/en/databank/working_reports
Wallerand J-P, Abou-Zeid A, Badr T, Balling P, Jokela J, Kugler R, Matus M, Merimaa M, Poutanen M, Prieto E, van den Berg S, Zucco M (2008) Towards new absolute long distance measurement systems in air. 2008 NCSL International Workshop and Symposium, Orlando (USA), Aug 2008. http://www.longdistanceproject.eu/files/towards_new_absolute.pdf
Acknowledgement
For the scale transfer, we have used the Kern Mekometer ME5000 of Helsinki University of Technology’s (TKK) Laboratory of Geoinformation and Positioning Technology as a transfer standard. We thank Professor Martin Vermeer and the rest of the staff there for their willing cooperation.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2012 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Jokela, J., Häkli, P., Poutanen, M., Kallio, U., Ahola, J. (2012). Improving Length and Scale Traceability in Local Geodynamical Measurements. In: Kenyon, S., Pacino, M., Marti, U. (eds) Geodesy for Planet Earth. International Association of Geodesy Symposia, vol 136. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-20338-1_8
Download citation
DOI: https://doi.org/10.1007/978-3-642-20338-1_8
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-20337-4
Online ISBN: 978-3-642-20338-1
eBook Packages: Earth and Environmental ScienceEarth and Environmental Science (R0)