Study of Ionosphere Total Electron Content for the Broadband Geodetic VLBI Fringe Model
Abstract
The radio telescopes used for Geodetic Very Long Baseline Interferometry (VLBI) receive signals from distant astronomical objects to provide a measure of the Earth's shape and variable rotation. However, the propagation of these signals through the Earth's ionosphere and any other plasma between the radio source and the telescope introduces a systematic error in the geodetic observable. This dispersive delay has become more critical in light of the accuracy goals set forth in the VLBI2010 specifications for the VLBI Geodetic Observing System (VGOS) which are 1mm for position and 0.1 mm/yr for stability. In order to achieve such geodetic accuracy, this error must be accurately removed. In this work we present an investigation of the accuracy of the dispersive component of delay as determined by the broadband geodetic VLBI technique. We will describe the features and implementation of a frequency-dependent forward model of this dispersive delay for VLBI. The application of this model yields an estimate of the combined ionospheric and extraterrestrial differential total electron content (TEC) using a nonlinear parametric search. We assess the quality of this VLBI-based differential TEC estimate by comparing it with differential TEC values obtained using GPS receivers near VLBI antennas.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.G53A0905M
- Keywords:
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- 1220 GEODESY AND GRAVITY Atmosphere monitoring with geodetic techniques