Minutes of the EUREF LAC Workshop (Frankfurt Am Main, Oct. 22-23, 2008)
by Heinz Habrich, Bundesamt für Kartographie und Geodäsie, Germany
Summary of Discussions/Action Items
The 6th EPN Local Analysis Centres Workshop was held on October 22-23, 2008 in Frankfurt am Main, Germany, hosted by the Federal Agency for Cartography and Geodesy (BKG). 33 registered workshop participants from 15 European countries visited the workshop and followed the 24 oral presentations. The workshop was organized in 6 working sessions, each with presentations and time for discussion, which was used intensively. The workshop programme is attached to the minutes.
An overview of recent developments of the existing EPN structure and products was given in working session 1 ("Reports from the EPN Coordination Group"). Carine Bruyninx announced a new tool for the compilation of site log-files, which is going to be established at the EPN Central Bureau (EPN CB). It will allow station operators to enter all requested information in dedicated data fields of a web-site and to successively generate the log-file format compliant text file. Heinz Habrich presented a draft comparison of two EPN cumulative solutions, one calculated by Ambrus Kenyeres within the scope of the EPN time series project and one by Heinz Habrich as results from the analysis coordinator. The final results of this initiative will be presented at the Technical Working Group (TWG) meeting on November 3-4, 2008.
10 Local Analysis Centres (LACs) explained in working session 2 ("Local Analysis Centres reports") their current activities and future plans. Bruno Garayt reported on plans of a scientific collaboration on GNSS permanent network analysis with an institution in Algeria (INCT). One of the objectives aims at becoming an EPN LAC, and potentially an AFREF LAC. Some additional contacts are on the way with an institution in Tunisia (OTC).
Rolf Dach summarized in working session3 ("Experiences with new processing strategies") the recent developments and plans of the Bernese Software through a comparison to the already released version 5.0. 14 of in total 16 LACs to compute the EPN products use bernese Software. New features of the software will allow to resolving GLONASS phase ambiguities, to apply modern troposphere mapping functions, e.g. Vienna mapping function or global mapping function, to define validity intervals for station coordinates and much more model changes. The release of the new software is not expected before year 2009 and for that reason new processing options have not been discussed during the workshop.
Ambrus Kenyeres compared in session 4 ("New analysis products") the EPN coordinate time series with a re-processed time series of the EPN network carried out by WUT/MUT and ROB. Beside other improvements the formal error and the number of jumps were significantly reduced in the re-processed solution. A discussion of new re-processing of the EPN network back to its beginning started among the workshop participants after that presentation. At least 6 LACs confirmed their plans to re-process the particular EPN sub-network and the analysis coordinator confirmed to take over the combination of the re-processed LAC solutions. It was agreed after some discussion to choose one person that overtakes the responsibility for the organizational and leading work of the re-processing. Christof Völksen declared to be prepared for this position. The next steps to push the EPN reprocessing will be taken by Christof Völksen. The EPN-CB will set up a data centre dedicated to the reprocessing; it will contain an on-line copy of all EPN data since the start of the EPN. A proposal for a reprocessing of the EPN shall be presented to the EUREF TWG in spring 2009.
Three presentations in session 5 ("Site, receiver, antenna and other issues") showed spectral analysis of EPN coordinate
time series. Well-known annual and semi-annual but also diurnal and semi-diurnal signals have been identified by means
of Fast-Fourier and Wavelet transformations. Valid absolute phase centre variations (APVCs) to be applied in EPN analysis
have been discussed. Günter Stangl raised the question, whether actual APCVs which are in the official IGS ANTEX file,
for particular Topcon antennae, should be used for EPN and especially the reprocessing. A lot of calibration values are
transformed from relative to absolute values only and not calibrated at the robot. Stefan Schaer pointed out that
consistency between IGS and EPN may be more important than correcting the APCVs. As the IGS re-processing is presently
performed, the IGS cannot update its ANTEX files for antennae that are presently in use within the IGS. Before the next
re-processing, however, the IGS will update its ANTEX files. It was concluded that for the moment the same APCV as the
IGS would be used (with the exception of the individual calibrations). In the mean time the EPN CB will gather the
necessary information concerning the missing APCV so that the ANTEX tables of the IGS can be updated as soon as allowed.
Elmar Brockmann proposed to publish at the EPN web site the ETRS89 coordinates of EPN stations officially adopted by the mapping agencies in the European countries. This is an important detail in the establishment of a European reference frame. The issue will be discussed within the TWG.
Jan Dousa presented a list of his ideas to stimulate discussion in working session 6 ("Wrap-up and closing session"). A couple of questions has been addressed and discussed:
The Workshop was closed after the discussion.
J. Ihde: Welcome address from the Federal Agency for Cartography and Geodesy
H. Habrich: Welcome and workshop objective, setup of final schedule
Working Session 1: Reports from the EPN Coordination Group
Chair: Elmar Brockmann
C. Bruyninx, J. Legrand, F. Roosbeek: EPN Coordination Status and Plans
H. Habrich: Report on the EPN Analysis
W. Söhne: EUREF-IP - from Pilot Project to operational status
A. Kenyeres: Report on the EPN Time Series Analysis
W. Söhne: Status of the EPN troposphere product
Working Session 2: Local Analysis Centres reports
Chair: Carine Bruyninx
M. Valdes Perez de Vargas, J. Sanchez Sobrino: Current status of IGE LAC
E. Brockmann, D. Ineichen, S. Schaer: LPT Analysis Center Report
G. Stangl, C. Aichhorn, S. Krauss: OLG LAC 2006-2008 - EPN related activities
M. Figurski, T. Liwosz, K. Szafranek: Report of the WUT EPN Local Analysis Centre
B. Garayt: IGN LAC Report
Working Session 2: Local Analysis Centres reports (cont'd)
Chair: Günther Stangl
C. Völksen, W. Wende: Activities at the BEK LAC
J. Legrand, Q. Baire, N. Bergeot, C. Bruyninx, P. Defraigne, S. Pireaux, E. Pottiaux: Current activities and research at ROB LAC
C. Ferraro, R. Pacione, F. Vespe: ASI LAC Report
A. Kenyeres: SGO LAC report
L. Jivall, J. Johansson: Status report from NKG LAC
Working Session 3: Experiences with new processing strategies
Chair: Ambrus Kenyeres
Working Session 4: New Analysis Products
Chair: Christof Völksen
A. Kenyeres, M. Figurski, J. Legrand: What can we expect from the EPN reprocessing ?
R. Pacione, F. Vespe, B. Pace, G. Colucci, D. Iacovone: ASI Near-Real Time products and related processing experiences
W. Söhne: Enhancement of EPN Real-Time Activities
Working Session 5: Site, receiver, antenna and other issues
Chair: Jan Hefty
J. Hefty, M. Igondova: Diurnal and semi-diurnal site coordinates variations resulting from processing with BV42 and BV50
K. Szafranek, M. Figurski, M. Galuszkiewicz: EPN reprocessed daily data analysis. Interpretation of disturbances caused by selected factors
P. Kaminski, M. Figurski: Time and frequency analysis of daily reprocessed solutions form selected EPN stations
Working Session 6: Wrap-up and closing session
Chair: Heinz Habrich
J. Dousa: LAC Questionnaire
All: Final Discussion