Geodesy Research at Newcastle University

1. Geodesy Research at Newcastle University Peter Clarke Professor of Geophysical Geodesy School of Civil Engineering and Geosciences Newcastle University United Kingdom

2. Academic Staff Prof. Peter Clarke Geophysical Geodesy Reference frames, GIA, loading, tectonics, GNSS Prof. Matt King Polar Geodesy Cryospheric applications of GNSS, GIA, sea level Dr Nigel Penna GNSS, tropospheric water vapour, loading Prof. Phil Moore Space Geodesy Orbit modelling, gravity, altimetry, SLR Prof. Philippa Berry Altimetric Engineering Inland and coastal altimetry Dr Stuart Edwards Engineering / industrial GNSS, geohazards

3. Research Staff Ian Martin GNSS PrecisePoint Positioning Kirill Palamartchouk Geophysical andionospheric GNSSapplications Liz Petrie Orbital & ionospheric errors in GNSS Sophie Bassett GIA, loading, andreference frames Rossen Grebenitcharsky Gravimetric geodesy and satellite orbits Robert Balmbra Altimetry Julien Gazeaux GPS time series analysis

4. Impact of future satellite systems onGNSS Precise Point Positioning • Russia’s GPS counterpart, GLONASS, being heavily developed • Shown on a static IGS site (JPLV) as an example • Improved convergence time with GLONASS • GLONASS improves the RMS position error due to improved geometry • Particularly useful for kinematic positioning and precise navigation GPS only GPS + GLONASS

5. Multipath and long GPS time series • Looking at effects of unmodelled time-constant carrier phase multipath on long GPS time series through simulation • Simulation considers precise point positioning approach • Uses real GPS orbits, which do vary with time • Proposed mitigation approach (black) works well 3. Simulated effect after mitigation 2. Simulated multipath effect (blue/magenta) Effects of unmodelled multipath on height at site in Antarctica (MCM4) 1. Real height series King, M. A., and C. S. Watson (2010), Long GPS coordinate time series: Multipath and geometry effects, J. Geophys. Res., 115, B04403

6. Sidereal filtering to improve small-scale deformation monitoring • Removing multipath-related coordinate errors • Using single-epoch GASPsoftware (in-house) • GPS sidereal period of 86154 s • Switchedantennafor localnetwork Ragheb et al., Proc. ION NTM, 2007; Ragheb et al., J. Geodesy, 2007; Ragheb et al., J. Surv. Engrg., 2010

7. Ocean tide loading and Earth structure • Significant anomaliesat M2 period in W Europe • Not explained by differencesbetween, or errors in, oceantide models • May be due to change in upper mantle elasticityat tidal periods • No other geophysicalsignal probes this frequency M2 residuals to GPS observations (FES2004 model) FES2004+PREM modelled M2 OTL Inter-model stdev, 10x scale Allinson et al., GRL, 2004; King et al., JGR, 2005; Thomas et al., J. Geodesy, 2007; Clarke & Penna, Surv. Rev.,2010;

8. Non-tidal ocean loading effects on geodetic GPS heights TERS Williams & Penna (2011), Geophys. Res. Lett. • Non-tidal (e.g. surge) ocean loading not considered in GPS analysis • Modelled land displacement according to the global ECCO model and the regional high resolution POLSSM model • Correlation of >0.7 with state-of-the-art GPS height time series • Reduces variance up to 30-40%, POLSSM slightly outperforming ECCO • Global high resolution non-tidal ocean models needed for geophysical GPS work

9. Precise orbit determination and satellite laser ranging In house software: Faust Lavallée, D. A., P. Moore, P. J. Clarke, E. J. Petrie, T. van Dam, and M. A. King (2010), J2: An evaluation of new estimates from GPS, GRACE, and load models compared to SLR, Geophys. Res. Lett., 37, L22403, doi:10.1029/2010GL045229.

10. Use of remote sensing data for discharge in ungauged catchments ERS2/ENVISAT altimetry data on Mekong. Satellite altimetry as virtual gauge data every 35 days Channel cross-sections from Landsat and SAR and different bathymetric depths for the 50km reach at Nakhon Phanom and Vientiane. Q = 7.22 W1.02 Y1.74 S0.35 Q discharge; W river width, Y water depth (m), S channel slope. Bjerklie et al. (2003) Measured and estimated stage-discharge relationships from 1996-2005 at Nakhon Phanom

11. International GNSS Service • Weekly combinationof GPS reference frame • In-house TANYA s/ware • Backup/check to officialIGS solution • Host of IGS 2010 Workshop

12. Observe mm level changes in Earth’s shape with global network of GPS receivers Invert shape for mass distribution using an elastic Earth model, like the spring in a set of scales + + = Tectonic Motion Postglacial rebound Loading deformation Secular Motion Surface mass loading deformation & the hydrological cycle Blewitt et al., Science,2001; Blewitt & Clarke, JGR, 2003; Gross et al., GRL, 2004; Clarke et al., GRL, 2005; Lavallée et al., JGR, 2006; Clarke et al., GJI, 2007; Lavallée et al., GRL, 2010

13. Antarctic GIA (models vs GPS) East Antarctica West Antarctica uplift rate (mm/yr) Thomas et al. (2011), Geophys. Res. Lett., 38, L22302

14. GPS deployments 2013-14 • Mt Wollard & Martin Hills (solar+wind) • Mt Johns solar only occupying existing site with historic data

15. Lower estimates of Antarctic sea level contribution from satellite gravimetry King, Bingham, Moore, Whitehouse, Bentleyand Milne (2012) Nature, 491, 586-589. Estimates of basin- scale Antarctic ice mass change from GRACE for Aug 2002 – Dec 2010 in Gt/yr. Best, lower and upper values. Continent-wide ice mass change of -69±18 Gt yr-1 (+0.19±0.05 mm yr-1 sea-level equivalent).

16. GNSS / geodesy consultancy and CPD • Network RTK benchmarking • CPD courses: • GNSS and Network RTK • High Precision GNSS using Post-processing • Least Squares Adjustment for Offshore Survey • Precise GNSS Positioning • deformation monitoring