Modelling physical correlation of GNSS phase observations by means of turbulence theory

Led by:	Prof. Dr.-Ing. Steffen Schön
E-Mail:	schoen@ife.uni-hannover.de
Team:	Dr.-Ing. Markus Vennebusch
Year:	2011
Date:	12-01-11
Funding:	DFG (SCHO 1314/1-1).
Is Finished:	yes

Methodology

Turbulent irregularities in the lower atmosphere cause physical correlations between GNSS observables. This is also true for VLBI or optical measurements from SLR, LLR, or the digital zenith camera. Based on turbulence theory, a variance-covariance model was developed that reflects these correlations for GPS phase observations. Using this model, a fully-populated variance-covariance matrice (VCM) for the observations is obtained. The main results are:

The obtained VCM depends not only on the satellite-station geometry but also on the prevailing atmospheric conditions.
The amount of the correlation between two GPS phase observations is inversely related to the separation distance of the corresponding ray paths through the turbulent atmosphere.

Figure 1: Simulated Variations of tropospheric total delays. The temporal behavior is modelled, using temporal structure functions. The mean average are reflected by the expected values determined by the turbulence theory.

Based on this Model, Sensitivity alaysises and simulations of the Variation of tropospheric total delays were carried out.

Figure 2: Spatial behavior of the tropospheric total delay, determined by ''Precise Point Positioning''-Solutions of a 16 km network of linear design measured by six GPS-Receiver.

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