D69 Regional combination methodology and report.
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This is part of work-package 9500 the purpose of which is:
Objectives: In a distributed network processing approach,
a method is required for ensuring the results from the processing
centres are compatible.
Methodology/Work Description: The International GPS Service
(IGS) has developed a method for combining ZTD solutions from different
processing centres by removing a bias between processing centres and
averaging the results. The same method is applied for the 12 analysis
centres of the EUREF Permanent GPS Network (EPN). Typical for IGS and
EUREF is, that almost all stations are processed by at least three
In our distributed network, only a subset of stations will be common
among processing centres, but these can be used to verify that there
are no offsets. Also, IGS and EUREF operate in post-processing mode.
The batch type of processing used by IGS and EUREF will be converted
into a Kalman filter approach that can be used in near real-time
applications. The differential biases between the analysis centres will
be modelled for the stations in common. Special techniques for the
detection, identification and adaptation of outliers and biases,
developed at TUD, will be used. Algorithms will be developed and
* Two possible refinements will be investigated
1. Extension or combination of the NRT combination with bias
reduction algorithms (using output from NWP analysis) to model absolute
2. The use of error correlation models to provide analysis centre
dependent corrections for stations that are not in common.
Both of these additional investigations are related to other
workpackages in this proposal.
* TUD will develop automated methodology for a regional combination of
solutions following the EUREF model, in order to provide the best
integrated product from the regional products. They will aid in the
implementation of this methodology at the processing centres.
Deliverable D69: The results are available in the report:
Sequential combination of regional
troposphere solutions. For further information contact Hans
van der Marel at the Technical University of Delft.