The focus of my research in this area is on measurement of solid earth tides, ocean tides and validation of ocean tide models, particularly in polar regions and using GPS. Further work relates to tidal forcing of ice shelf and ice streams, resulting in tidal modulation of ice flow. To help visualise loading displacements of Earth, see the animation of a model of UK ocean tide loading displacements.
Active Projects
Funding: Co-I, NERC-funded project (NE/D009960/1), £390k; PI, NERC Geophysical Equipment Facility award, £101k
In the 2007/8 Antarctic summer season, 15 GPS receivers were deployed on (13) and around (2) the Filchner-Ronne and Larsen C ice shelves with the purpose of providing new tidal data and examining the tidal modulation of flow. Nine of the sites remained for the 2008 austral winter, 6 powered with over-winter power systems, and were retrieved in early 2009. Good data records have been obtained from each site (apart from FR01). Almost continuous, year-long records have been retrieved at FR05, FR07, FR09 and LAR2. The LAR2 site was left for a further year and will be retrieved in early 2010. Initial results from the tidal analysis from a subset of the sites is underway and these will be assimilated into a new Antarctic tide model in the near future in collaboration with Laurie Padman.
Funding: Contractor investigating aliasing of ocean tides into potential future gravity field missions, (~£10k to Newcastle)
The Newcastle geodesy group has pioneered the application of GPS to study of harmonic displacements, mainly for the purpose of investigating ocean tide loading displacements. At certain tidal bands, agreement has been demonstrated at the 0.2-0.3mm level with models. Ocean tide models around Antarctica have been validated.
Funding: Co-I, NERC-funded project (NE/C003438/1), £128k
Our group is working on the anelasticity of Earth at tidal periods using a global network of GPS receivers. Models of anelasticity are relatively well-observed at longer periods, but are untested in the diurnal and semidiurnal bands.
Tidal modulation of ice stream and ice shelf flow (ongoing)
A large number of Antarctica's ice streams and ice shelves (but not all) are now known to have their flow modulated by tides. A major advance came from continuous GPS measurements and advanced GPS data analysis techniques. See here for further information.
Recent Paper Highlights
Thomas, I.D., M.A. King, and P.J. Clarke. in press. A validation of ocean tide models around Antarctica using GPS measurements of ocean tide loading. In A. Capra, and R. Dietrich, ed. Geodetic and geophysical observations in polar regions: overview in perspective of the International Polar Year, Springer
Thomas, I.D., M.A. King, and P.J. Clarke. 2007. A comparison of GPS, VLBI and model estimates of ocean tide loading displacements, J. Geod., 81, 359-368, doi:10.1007/s00190-006-0118-9
King, M.A. and L. Padman. 2005. Accuracy assessment of ocean tide models around Antarctica, Geophysical Research Letters, 32, L23608, doi:10.1029/2005GL023901.
This site was last updated
27-Jul-2010