Subdiurnal earth orientation parameters from VLBI networks — determinability and significance

Abstract

As Very Long Baseline interferometry (VLBI) is the geodetic space technique which directly links terrestrial and celestial reference frames, it is particularly suitable to determine the Earth orientation parameters (EOP). Efforts have been made from several groups to derive the EOP with subdiurnal resolution. To avoid misleading interpretations it is worthwhile to study the quality of such highly resolved parameters from a statistical point of view focussing on standard VLBI observations and processing. Main subject of interest is the role of the observation configuration and of the chosen temporal resolution.The respective normal equations of the leastsquares parameter estimation are analyzed to illustrate the precision of the estimated EOP for different input scenarios. The correlations between individual EOP or parameter groups with influence on the EOP are studied. Eigenvalue decompositions are performed to check for structures in the precision of the parameters. The significance of the highly resolved EOP is tested using statistical methods. In the numerical part of the study, two representative VLBI networks (NEOS-A, CORE-A) are treated in detail. The VLBI data are processed using the software package OCCAM 5.0 LSM.KeywordsVery Long Baseline InterferometryEarth orientation parameterseigenvalue decompositionsstatistical tests