Derivation Of Refractive Index And Temperature Gradients From Optical Scintillometry To Correct Atmospherically Induced Errors For Highly Precise Geodetic Measurements
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
Refraction effects of optical beams are generally caused by an inhomogeneous propagation medium and are a major source of systematic errors in the precise optical determination of angles and distances in the atmospheric surface layer. In this contribution a method for deriving vertical temperature and refractive index gradients from optical scintillation is presented. Knowledge of these gradients is required for the compensation of atmospherically induced errors for highly precise terrestrial geodetic measurements, like direct transfer and levelling. The advantage of the present optical method is, that temperature and refractive index gradients can be derived as line-averaged values over the propagation path, which is not possible by meteorological point measurements. Field observations have been carried out with a displaced-beam scintillometer over flat terrain and under different atmospheric conditions in order to verify this method. The experiments show, that this method allows to derive accurate correction values for precise terrestrial geodetic measurements.
- Böckem, B., Flach, P., Weiss, A., and Hennes, M.: 2000, Refraction influence analysis and investigations on automated elimination of refraction effects on geodetic measurements, Proc. IMEKO 2000, September 25–28, 2000, Vienna, Austria.
- Champagne, F.H., Friehe, C.A., La Rue, J.C., and Wyngaard, J.C.: 1977, Flux measurements, flux estimation techniques, and fine-scale turbulence measurements in the unstable surface layer over land, J. Atmos. Sci. 34, 515–530.
- Hill, R.J. and Clifford, S.F.: 1978, Modified spectrum of atmospheric temperature fluctuations and its application to optical propagation, J. Optical Soc. of America 68(7), 892–899.
- Högström, U.: 1988, Non-dimensional wind and temperature profiles in the atmospheric surface layer: A re-evaluation, Boundary-Layer Meteorology 42, 55–78.
- Lawrence, R.S. and Strohbehn, J.W.: 1970, A survey of clear-air propagation effects relevant to optical communications, Proc. of the IEEE 58(10), 1523–1545.
- Möser, M., Müller, G., Schlemmer, H., and Werner, H.: 2000, Handbuch der Ingineurgeodäsie-Grundlagen, 3. neubearbeitet Auflage, Wichmann, Heidelberg.
- Stull, R.B.: 1988, An Introduction to Boundary Layer Meteorology, Kluwer Academic Publishers.
- Thiermann, V.: 1992, A displaced-beam scintillometer for line-averaged measurements of surface layer turbulence, 10th Symposium on Turbulence and Diffusion, 29 September–2 October 1992, Portland, OR.
- Weiss, A.I., Hennes, M., and Rotach, M.: 1999, Comparison of turbulence parameters derived from optical scintillometry and the eddy-correlation technique over flat terrain, Proc. 13th Symposium on Boundary Layers and Turbulence, Amer. Meteor. Soc., Dallas, pp. 145–146.
- Wesely, M.L. and Alcaraz, E.C.: 1973, Diurnal cycles of refractive index structure function coefficient, J. of Geophysical Research 78(27), 6224–6232.
- Derivation Of Refractive Index And Temperature Gradients From Optical Scintillometry To Correct Atmospherically Induced Errors For Highly Precise Geodetic Measurements
Surveys in Geophysics
Volume 22, Issue 5-6 , pp 589-596
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers
- Additional Links
- refractive index
- sensible heat flux
- Industry Sectors
- Author Affiliations
- 1. Institute of Geodesy and Photogrammetry, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
- 2. Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland