Analysis of the first year of Earth rotation parameters with a sub-daily resolution gained at the CODE processing center of the IGS

 The solutions of the CODE Analysis Center submitted to the IGS, the International Global Position System (GPS) Service for Geodynamics, are based on three days of observation of about 80–100 stations of the IGS network. The Earth rotation parameters (ERPs) are assumed to vary linearly over the three days with respect to an a priori model. Continuity at the day boundaries as well as the continuity of the first derivatives are enforced by constraints. Since early April 1995 CODE has calculated a new ERP series with an increased time resolution of 2 hours. Again continuity is enforced at the 2-hours-interval boundaries. The analysis method is described, particularly how to deal with retrograde diurnal terms in the ERP series which may not be estimated with satellite geodetic methods. The results obtained from the first year of data covered by the time series (time interval from 4 April 1995 to 30 June 1996) are also discussed. The series is relatively homogeneous in the sense of the used orbit model and the a priori model for the ERPs. The largest source of excitation at daily and sub-daily periods is likely to be the effect of the ocean tides. There is good agreement between the present results and Topex/Poseidon ocean tide models, as well as with models based on Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data. Non-oceanic periodic variations are also observed in the series. Their origin is most probably a consequence of the GPS solution strategy; other possible sources are the atmospheric tides.

Authors and Affiliations

1.  Department of Theoretical Geodesy, Slovak University of Technology, Radlinskeho 11, 813 68 Bratislava, Slovakia e-mail: hefty@cvt.stuba.sk; Tel.: +421 7 5249 8047; Fax: +421 7 5292 5476, , , , , , SK

   J. Hefty

2.  Institute of Astronomical and Physical Geodesy, Technical University of Munich, Arcistrasse 21, 80333 Munich, Germany e-mail: markus.rothacher@bv.tum.de; Tel.: +49 89 289 23191; Fax: +49 89 289 23178, , , , , , DE

   M. Rothacher

3.  Astronomical Institute, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland e-mail: beutler@aiub.unibe.ch; Tel.:+41 31 631 85 91; Fax: +41 31 631 3869, , , , , , CH

   T. Springer & G. Beutler

4.  Institute of Geodesy and Geophysics, University of Technology, Gusshausstrasse 27-29, 1040 Vienna, Austria e-mail: rweber@luna.tuwien.ac.at; Tel.: +43 1 58801 12865; Fax: +43 1 504 2155, , , , , , AT

   R. Weber

Received: 13 July 1999 / Accepted: 21 March 2000

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