The Status and Development of the
APREF GNSS Network
Guorong Hu
Geodesy, Geoscience Australia, Canberra, Australia
Outline
Introduction
Objectives
How the reference frame is derived
Services and applications
Quality control of APREF GNSS data and solutions
Concluding remarks
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
ANU Geodesy Meeting, 1-2 July 2014
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 1.3b
South America (SIRGAS)
Sub-commission 1.3c
North America (NAREF)
Sub-commission 1.3d
Africa (AFREF)
Sub-commission 1.3e
Asia Pacific (APREF)
Sub-commission 1.3f
Antarctic (SCAR)
APREF structure
APREF Steering
Committee
Chair: J. Dawson
Central Bureau –
Geoscience Australia
Tasks: coordination of analysis and data-flow, user interaction, advice to the Steering Committee.
Analysis Centre
Analysis Centre
APREF Users
UN-GGIM-AP, government agencies, IAG, FIG, research community and
private sector
Data Centre
Data Centre
GNSS
Network Operator
GNSS
Network Operator
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
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
Example of APREF benefits: densification of velocity
field model in Asia-Pacific and the long-term
maintenance of the APREF
ANU Geodesy Meeting, 1-2 July 2014
For the maintenance of a
geodetic reference frame the
following characteristics of the
site velocities are critical:
magnitude
accuracy
XXV FIG Congress, Kuala Lumpur, Malaysia, 16-21 June 2014
Example of APREF benefits: GNSS monitoring of
earthquake displacement at MQZG – New Zealand
Event 3: 13-Jun-11 Christchurch earthquake (6.0)
Event 1: 03-Sep-10 Christchurch earthquake (7.1)
Event 2: 22-Feb-11
Christchurch earthquake
(6.3)
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 2014
0 100 200 300 400 500 600 700Numb
e
r of s
tations
Year
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…..
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
ANU Geodesy Meeting, 1-2 July 2014
What is the status of the APREF
How the reference frame derived
APREF Combination
Independent
SINEX
Solutions (Bernese and
other GPS software)
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
ITRF2008 (IGb08)
Geoscience Australia (AUS)
Curtin Uni. (CUT)
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
APREF data and products availability
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:
http://192.104.43.25/status/solutions/analysis.html
APREF data and products are provided with an open access data policy
via the internet following the practice of the IGS.
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
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 (email): feedback to site operators
e-Geodesy: web service for metadata management
learning from IGS community
Data quality control and monitoring of
APREF GNSS Network
Monitoring example
Short-term coordinate monitoring for station
equipment change: update of the equipment is
unavoidable due to equipment failure or upgrading
ANU Geodesy Meeting, 1-2 July 2014
Antenna failure and changed at site
YULA, Yulara, NT on 20 Nov 2013
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.
Investigation of CORS position time series
residuals sources: typical example
ANU Geodesy Meeting, 1-2 July 2014
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)
ANU Geodesy Meeting, 1-2 July 2014
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 (2012.06.10
–
2012.06.16)
Average RMS of repeatability of 464 stations
North (mm) East (mm)
Up (mm)
with CONZ,
ANTC
2.6
2.2
5.8
without CONZ,
ANTC
1.4
1.5
4.5
improved
46%
32%
22%
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
http://www.ga.gov.au/earth-monitoring/geodesy/asia-pacific-reference-frame.html
APREF website for more information
Thank you for your attention
Phone: +61 2 6249 9884 Web: www.ga.gov.au
Email: [email protected]
Address: Cnr Jerrabomberra Avenue and Hindmarsh Drive, Symonston ACT 2609 Postal Address: GPO Box 378, Canberra ACT 2601
