1. Toulouse 2002 Dunedin Lyttelton Wellington Auckland Correcting New Zealand’s long-term sea level records for tectonic uplift using continuous GPS observations Paul Denys John Beavan Dion Matheson Mikael Denham Chris Pearson John Hannah

2. Toulouse 2002 Paired CGPS and CGPS@TG sites Sites with ~100 years of TG recordsSites with ~100 years of TG records CGPS close or collocated with TG recordersCGPS close or collocated with TG recorders But … Problems …But … Problems … TG sites not stableTG sites not stable Possible GPS masking problemsPossible GPS masking problems High multipath environmentsHigh multipath environments Requires careful monitoringRequires careful monitoring AUCK & TAKL WGTN & WGTT MQZG & LYTT OUSD & DUNT

3. Toulouse 2002 Tide Gauge Site Stability Monitoring Local stability:TG pole/recorder to local benchmarksLocal stability:TG pole/recorder to local benchmarks Regional stability:CGPS@TG to regional CGPSRegional stability:CGPS@TG to regional CGPS CGPS to CGPS@TG (km) TG to CGPS@TG (km) CGPS@TG to TG Connection Method Auckland27.3Collocated Spirit level Wellington4.20.55 Spirit level + GPS Lyttelton12.1Collocated Spirit level Dunedin11.10.4

4. Toulouse 2002 Ports of Auckland Tide Gauge and TAKL CGPS Station Located on Captain Cook Wharf, Auckland Located on Captain Cook Wharf, Auckland Tide gauge measurement system uses microwaves reflected off sea surface beneath wharf Tide gauge measurement system uses microwaves reflected off sea surface beneath wharf Reference surface of tide gauge is immediately adjacent to base of GPS antenna Reference surface of tide gauge is immediately adjacent to base of GPS antenna Tide Gauge mounted under this cover CGPS antenna (TAKL) Base of antenna mast firmly bolted to wharf

5. Toulouse 2002 GPS receiver Industrial PC on internet Power Supply/ Battery charger Back-up battery CGPS Receiver at Ports of Auckland

6. Toulouse 2002 Automatic tide gaugeManual gauge Measuring system at Wellington float-type tide gauge

7. Toulouse 2002 WGTT Continuous GPS Station Mast is attached through facing onto the main structural wall of the museum

8. Toulouse 2002

9. Install Temporary GPS (WGTA) 50 m from TGBM for 24 hours every 3 months Same antenna type and radome used at WGTT and WGTA Level TGBM and WGTA several times during 24 hour period GPS Baseline Processing Troposphere variation solved at WGTT as part of regional network processing Same troposphere variation assumed at WGTA as at WGTT when solving for the WGTT - WGTA height difference Another CGPS site, WGTN, is located in bedrock 5.5 km from WGTT Provides a check on the stability of WGTT HEIGHT CONNECTION from WELLINGTON TIDE GAUGE BENCH MARK (TGBM) to CONTINUOUS GPS (WGTT)

10. Toulouse 2002 Location of WGTT CGPS (at Te Papa) Temporary GPS used to tie between tide gauge BM and WGTT GPS levelling: temporary GPS to WGTT CGPS

11. Toulouse 2002 Temporary GPS used to tie between tide gauge BM and WGTT Precise levelling: Wellington tide gauge to temporary GPS Level

12. Toulouse 2002 Precise and GPS levelling results: Wellington tide gauge

13. Toulouse 2002 Combined geodetic and GPS levelling results Wellington tide gauge

14. Toulouse 2002 Structure Stability Problems: Wooden Wharf at Lyttelton Tide Gauge Hut and and GPS antenna

15. Toulouse 2002 CGPS@TG site TG recorder and tide pole Port Chalmers: Poor GPS Environment

16. Toulouse 2002 Regional Stability: CGPS to CGPS@TG

17. Toulouse 2002 rms of Baseline Components and Vertical Velocity rms of Baseline Components and Vertical Velocity Baseline Distance (km) Latitude (mm) Longitide (mm) Height (mm) Velocity (mm/yr) OUSD- DUNT 11.1  1.9  1.8  5.9  0.6 MQZG- LYTT 12.1  4.6  2.5  4.5  0.7 WGTN- WGTT 4.2  2.4  3.6  5.7  1.2 AUCK- TAKL 27.3  1.6  1.8  6.9  8.8

18. Toulouse 2002 Tide Gauge Mean Annual Sea Level Record: June 2002 SeaLevel true = SeaLevel measured +/- ???

19. Toulouse 2002 New Zealand’s CGPS @TG Project CGPS installed at 4 long record TG locationsCGPS installed at 4 long record TG locations CGPS collocated or within 600mCGPS collocated or within 600m Site stability monitored using a variety of methodsSite stability monitored using a variety of methods Precise levelling to close BMsPrecise levelling to close BMs GPS “levelling” to regional CGPS and TG BMGPS “levelling” to regional CGPS and TG BM CGPS to CGPS @TG stabilityCGPS to CGPS @TG stability Baselines 4, 11, 12 & 27kmBaselines 4, 11, 12 & 27km Horz rms  2-3mmHorz rms  2-3mm (excluding MQZG-LYTT) Vert rms  5-7mmVert rms  5-7mm Vert vel ~1mm/yrVert vel ~1mm/yr (excluding AUCK-TAKL)