Regional biases in absolute sea-level estimates from tide gauge data due to residual unmodeled vertical land movement

• Published in: Geophysical research letters Vol. 39; no. 14
• Main Authors: King, Matt A., Keshin, Maxim, Whitehouse, Pippa L., Thomas, Ian D., Milne, Glenn, Riva, Riccardo E. M.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 28-07-2012; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: absolute sea level; bias; Climate change; Cryosphere; Earth; Earth sciences; Earth structure; Earth, ocean, space; Exact sciences and technology; Gages; Gauges; Geodetics; Geographic information systems; Global Positioning System; Global positioning systems; GPS; Land; Marine; Movement; Ocean-atmosphere interaction; Physical oceanography; relative sea level; Satellite navigation systems; Sea level; Tides; vertical land movement; models; trend-surface analysis; sensitivity analysis; Bias; Tide gauge; Regional scope; ice; global; velocity; Global Positioning System; Earth; Referential; uplifts; Planetary scale; sea level
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2012GL052348

The only vertical land movement signal routinely corrected for when estimating absolute sea‐level change from tide gauge data is that due to glacial isostatic adjustment (GIA). We compare modeled GIA uplift (ICE‐5G + VM2) with vertical land movement at ∼300 GPS stations located near to a global set of tide gauges, and find regionally coherent differences of commonly ±0.5–2 mm/yr. Reference frame differences and signal due to present‐day mass trends cannot reconcile these differences. We examine sensitivity to the GIA Earth model by fitting to a subset of the GPS velocities and find substantial regional sensitivity, but no single Earth model is able to reduce the disagreement in all regions. We suggest errors in ice history and neglected lateral Earth structure dominate model‐data differences, and urge caution in the use of modeled GIA uplift alone when interpreting regional‐ and global‐ scale absolute (geocentric) sea level from tide gauge data.
Key Points
Modeled GIA and observed GPS uplift rates near global tide gauges are compared
Regionally coherent differences reach +/‐ 1‐2 mm/yr
Sea level studies using GIA models alone will be regionally biased