Non-linear VLBI station motions and their impact on the celestial reference frame and Earth orientation parameters

The increasing accuracy and growing time span of Very Long Baseline Interferometry (VLBI) observations allow the determination of seasonal signals in station positions which still remain unmodelled in conventional analysis approaches. In this study we focus on the impact of the neglected seasonal signals in the station displacement on the celestial reference frame and Earth orientation parameters. We estimate empirical harmonic models for selected stations within a global solution of all suitable VLBI sessions and create mean annual models by stacking yearly time series of station positions which are then entered a priori in the analysis of VLBI observations. Our results reveal that there is no systematic propagation of the seasonal signal into the orientation of celestial reference frame but position changes occur for radio sources observed non-evenly over the year. On the other hand, the omitted seasonal harmonic signal in horizontal station coordinates propagates directly into the Earth rotation parameters causing differences of several tens of microarcseconds.

[1]  Z. Altamimi,et al.  ITRF2008: an improved solution of the international terrestrial reference frame , 2011 .

[2]  Zuheir Altamimi,et al.  Strategies to mitigate aliasing of loading signals while estimating GPS frame parameters , 2011, Journal of Geodesy.

[3]  M. Cheng,et al.  Variations in the Earth's oblateness during the past 28 years , 2004 .

[4]  Y. Bock,et al.  Anatomy of apparent seasonal variations from GPS‐derived site position time series , 2001 .

[5]  Geoffrey Blewitt,et al.  Crustal displacements due to continental water loading , 2001 .

[6]  Yu Qin,et al.  Vertical profile and origin of wintertime tropospheric ozone over China during the PEACE-A period , 2004 .

[7]  O. Titov,et al.  Seasonal variations in radial components of VLBI stations , 2000 .

[8]  Leonid Petrov,et al.  Study of harmonic site position variations determined by very long baseline interferometry , 2003 .

[9]  Ian Joughin,et al.  Numerical modeling of ocean‐ice interactions under Pine Island Bay's ice shelf , 2007 .

[10]  Harald Schuh,et al.  VLBI: A fascinating technique for geodesy and astrometry , 2012 .

[11]  David Eriksson,et al.  Continental hydrology loading observed by VLBI measurements , 2011, Journal of Geodesy.

[12]  O. Francis,et al.  Modelling the global ocean tides: modern insights from FES2004 , 2006 .

[13]  Jeffrey P. Walker,et al.  THE GLOBAL LAND DATA ASSIMILATION SYSTEM , 2004 .

[14]  Kaihua Ding,et al.  Evaluating seasonal loading models and their impact on global and regional reference frame alignment , 2014 .

[15]  Xiaoli Ding,et al.  Seasonal and secular positional variations at eight co-located GPS and VLBI stations , 2005 .

[16]  T. Artz,et al.  VLBI terrestrial reference frame contributions to ITRF2008 , 2010 .

[17]  Xavier Collilieux,et al.  Nontidal ocean loading: amplitudes and potential effects in GPS height time series , 2012, Journal of Geodesy.

[18]  Peter Steigenberger,et al.  Vertical deformations from homogeneously processed GRACE and global GPS long-term series , 2011 .

[19]  Xavier Collilieux,et al.  Comparison of very long baseline interferometry, GPS, and satellite laser ranging height residuals from ITRF2005 using spectral and correlation methods , 2007 .

[20]  Peter Steigenberger,et al.  Annual deformation signals from homogeneously reprocessed VLBI and GPS height time series , 2009 .

[21]  Leonid Petrov,et al.  Study of the atmospheric pressure loading signal in very long baseline interferometry observations , 2003, physics/0311096.

[22]  Harald Schuh,et al.  The New Vienna VLBI Software VieVS , 2012 .

[23]  H. Schuh,et al.  Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium‐Range Weather Forecasts operational analysis data , 2006 .

[24]  C. Jakob,et al.  A comparison of cloud properties at a coastal and inland site at the North Slope of Alaska , 2001 .

[25]  Robert W. Schunk,et al.  Utah State University Global Assimilation of Ionospheric Measurements Gauss‐Markov Kalman filter model of the ionosphere: Model description and validation , 2006 .

[26]  G. Blewitt,et al.  A New Global Mode of Earth Deformation: Seasonal Cycle Detected , 2001, Science.

[27]  E. F. Arias,et al.  THE SECOND REALIZATION OF THE INTERNATIONAL CELESTIAL REFERENCE FRAME BY VERY LONG BASELINE INTERFEROMETRY , 2015 .

[28]  Axel Nothnagel,et al.  Conventions on thermal expansion modelling of radio telescopes for geodetic and astrometric VLBI , 2009 .

[29]  W. Dick,et al.  The International Earth Rotation and Reference Systems Service (IERS) , 2004 .

[30]  V. Freudenthaler,et al.  Long-range transport of Saharan dust to northern Europe : The 11-16 October 2001 outbreak observed with EARLINET , 2003 .

[31]  Z. Malkin.  Impact of seasonal station motions on VLBI UT1 intensives results , 2013, Journal of Geodesy.

[32]  Harald Schuh,et al.  Atmospheric loading corrections at the observation level in VLBI analysis , 2009 .

[33]  Harald Schuh,et al.  Very Long Baseline Interferometry for Geodesy and Astrometry , 2013 .