Abstract
The periodic actions provoked by the tidal potencial on portions of continents, oceans and atmosphere cause direct and indirect effects on the earth’s crust (Melchior, 1983). The induced deformations cannot be neglected when dealing with high-accuracy geodetic positioning, specially in view of the diurnal and semi-diurnal tidal components. The dynamic effects of earth tides, and the loading coming from variations in atmospheric pressure and the indirect effect of the oceans on these frequencies (Farrel, 1972), have significant amplitudes in both low and middle latitudes. A discussion on the validity of a simple application of response models for correcting positions is pertinent.
An experiment was devised in order to verify how adequate predicted corrections of tides are. This experiment was carried out over a 315 km long continental profile, along the S-N direction, in Southern Brazil. Three sites were stablished on this profile carrying out simultaneous multi-parametric obeservations, being one site located on seashore (in Imbituba), the second 50 km away from the sea (Blumenau) and the third one 80 km inland (in Curitiba). In each one of them it was installed a dual-frequency GPS receiver, a gravimeter for observation of gravimetric tides, and atmospheric pressure and temperature sensors. In addition, a tide gauge was installed at the coastal site aiming to control local ocean effects. As a first step of the study, we established an initial multiparametric analysis for the coastal station, trying to find the local admitance among some envolved parameters. For this purpose, we used hourly observed values from gravity tide, ocean tide and air pressure. Results of this analysis, including interactions and instrumental effects, are discussed in this paper. In a next step, we intend to extend the analysis to the other two stations of the network and to include GPS hourly positions to check the crustal deformation and compare them with both predicted and observed gravity tides, corrected from air pressure and ocean load.
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© 1998 Springer-Verlag Berlin Heidelberg
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de Freitas, S.R.C., Santos, M.C., Cordini, J., Marone, E. (1998). Multi-Parametric Experiment for Observing Crustal Deformations in Southern Brazil. In: Forsberg, R., Feissel, M., Dietrich, R. (eds) Geodesy on the Move. International Association of Geodesy Symposia, vol 119. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-72245-5_70
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DOI: https://doi.org/10.1007/978-3-642-72245-5_70
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