The Status and Development of the APREF GNSS Network Guorong Hu

Transcription

1 The Status and Development of the APREF GNSS Network Guorong Hu Geodesy, Geoscience Australia, Canberra, Australia

2 Outline Introduction Objectives How the reference frame is derived Services and applications Quality control of APREF GNSS data and solutions Concluding remarks

3 Introduction Joint IAG and UN-GGIM-AP Initiative APREF mandated by UNRCC Resolution Endorsed by the UNOOSA, FIG and IGS Call for Participation: 1 March 2010 UN-GGIM-AP United Nations Global Geospatial Information Management for Asia and the Pacific UNRCC - United Nations Regional Cartographic Conference UNOOSA - United Nations Office for Outer Space Affairs

4 International Association of Geodesy (IAG) IAG Commission 1 Reference Frames Sub-commission 1.3 Regional Reference Frames Sub-commission 1.3a Europe (EUREF) Sub-commission 1.3c North America (NAREF) Sub-commission 1.3e Asia Pacific (APREF) Sub-commission 1.3b South America (SIRGAS) Sub-commission 1.3d Africa (AFREF) Sub-commission 1.3f Antarctic (SCAR)

5 APREF structure APREF Steering Committee Chair: J. Dawson APREF Users UN-GGIM-AP, government agencies, IAG, FIG, research community and private sector Central Bureau Geoscience Australia Tasks: coordination of analysis and data-flow, user interaction, advice to the Steering Committee. Data Centre Analysis Centre Data Centre Analysis Centre GNSS Network Operator GNSS Network Operator

6 What are the goals of the APREF Currently, APREF is all about sharing GNSS CORS data and its analysis The broad objective of APREF is to Create and maintain an accurate and densely realised geodetic framework, based on continuous observation and analysis of GNSS data Note that the APREF follows IGS practice, each participating organization contributes its own resources, and there is no central source of funding

7 What are the benefits of the APREF Major benefits of participation Improving and continuous link between national datum and CORS networks to the ITRF Dense GNSS network in Asia Pacific Contributing to regional dense velocity fields Independent GNSS data quality and site monitoring Improving access to GNSS data Pushing forward the scientific analysis and use of the national GNSS products Providing an opportunity and a forum towards improving the regional geodetic infrastructure ANU Geodesy Meeting, 1-2 July 2014

8 Example of APREF benefits: densification of velocity field model in Asia-Pacific and the long-term maintenance of the APREF For the maintenance of a geodetic reference frame the following characteristics of the site velocities are critical: magnitude accuracy reliability

9 Example of APREF benefits: GNSS monitoring of earthquake displacement at MQZG New Zealand Event 1: 03-Sep-10 Christchurch earthquake (7.1) Event 2: 22-Feb-11 Christchurch earthquake (6.3) Event 3: 13-Jun-11 Christchurch earthquake (6.0) XXV FIG Congress, Kuala Lumpur, Malaysia, June 2014

10 Number of stations What is the status of the APREF As of June 2014 Data from 28 countries 16 national agencies participating 2 universities participating ~ 420 Asia Pacific CORS stations data now available ~ 600 stations routinely analysed Data contributed from 7 CORS sites in Malaysia (JUPEM) since end of 2013 MoU signed with NAMRIA of Phillippines for PageNET data sharing in Feb Year ANU Geodesy Meeting, 1-2 July 2014

11 What is the status of the APREF Network Number of stations ARGN/AuScope/AGOS 123 SPRGN 12 CORSnet-NSW 112 VICNET 94 (50 sites added in 2013) SUNPOS 10 NTLANDS 5 GEONET 43 IGS 197 (132 core sites) Other APREF/NGS/IPS 50 (7 sites from Malaysia added in 2013) Total 646 ~ 90 stations from SmartNet Aus coming soon..

12 What is the status of the APREF Network Number of stations ARGN/AuScope/AGOS 123 SPRGN 12 CORSnet-NSW 112 VICNET 94 (50 sites added in 2013) SUNPOS 10 NTLANDS 5 GEONET 43 IGS 197 (132 IGS core sites) Other APREF/NGS/IPS 50 (7 sites from Malaysia added in 2013) Total 646

13 How the reference frame derived APREF Combination Geoscience Australia (AUS) Curtin Uni. (CUT) Victoria DTPLI (VIC) Independent SINEX Solutions (Bernese and other GPS software) ITRF2008 (IGb08) CATREF Software: combination after SINEX solutions cleaning, outlier and offset detection and elimination APREF combined solution: position and velocity estimates in IGb08, time series plots

14 Routine analysis of APREF GNSS Network Routine analysis, products including: Rapid solutions Final solutions Weekly combined solutions Position time series Contributions to: IAG (e.g., global vel fields) UN-GGIM-AP Australian next generation datum

15 APREF data and products availability APREF data and products are provided with an open access data policy via the internet following the practice of the IGS. Daily GNSS RINEX data with a delay of 24 hr after observation, see: ftp://ftp.ga.gov.au/geodesy-outgoing/gnss/data/daily/ Station log files, see: ftp://ftp.ga.gov.au/geodesy-outgoing/gnss/logs/ Weekly updated coordinate estimates in SINEX format, see: ftp://ftp.ga.gov.au/geodesy-outgoing/gnss/solutions/apref/ Geoscience Australia s APREF routine analysis solutions, see: ftp://ftp.ga.gov.au/geodesy-outgoing/gnss/solutions/final/ ftp://ftp.ga.gov.au/geodesy-outgoing/gnss/solutions/rapid/ APREF network and time-series plots, see:

16 Data quality control and monitoring of APREF GNSS Network What to monitor site operating status metadata: log file updating data quantity: availability and completeness data quality: cycle slips, multipath satellite tracking performance site position: monument stability

17 Data quality control and monitoring of APREF GNSS Network How to monitor existing tool: teqc on observation level moving on to use BNC for multi-gnss RINEX 3.x? post-processing analysis: rapid solution and final solution long-term performance monitoring: site coordination time series automatic alert system ( ): feedback to site operators e-geodesy: web service for metadata management learning from IGS community

18 Monitoring example Short-term coordinate monitoring for station equipment change: update of the equipment is unavoidable due to equipment failure or upgrading Antenna failure and changed at site YULA, Yulara, NT on 20 Nov 2013 Yulara CORS station in NT

19 Monitoring example Long-term stability and reference frame monitoring using stations with uninterrupted time series Alice Springs (ALIC) station event: antenna cable had small amounts of corrosion at the antenna end and changed on 20 July 2011.

20 Investigation of CORS position time series residuals sources: typical example Lalber CORS station in VIC

21 Investigation of CORS position time series residuals sources Seasonal signals Data quality variations Hardware issues Antenna mis-calibration Metadata errors Reference frame change Analysis strategy change Mis-modeling (atmosphere)..

22 Does unstable IGS reference station impact the solutions of our routine analysis? And how? Case study: two unstable IGS core stations CONZ, ANTC in Chile, caused by big earthquake (? Year), impacted the weekly combined solutions in terms of RMS of position repeatability, e.g., in GPS week 1692 ( ) Average RMS of repeatability of 464 stations with CONZ, ANTC without CONZ, ANTC North (mm) East (mm) Up (mm) improved 46% 32% 22%

23 Concluding remarks Very promising products Issues remain regarding free and open access to data for many Asia-Pacific countries Need to identify additional analysis centres limited redundancy with only 3 analysis groups Challenges Metadata management, especially for geophysical applications, stability and reliable metadata on equipment are issues Enhanced data quality monitoring: monitoring visualizations and automation Moving on multi-gnss tracking, monitoring and analysis (e.g., RINEX V3.x) Evaluation of accuracy and reliability of APREF products

24 APREF website for more information

25 Thank you for your attention Phone: Web: Guorong.Hu@ga.gov.au Address: Cnr Jerrabomberra Avenue and Hindmarsh Drive, Symonston ACT 2609 Postal Address: GPO Box 378, Canberra ACT 2601