Determination and characterization of 20th century global sea level rise

In this study, we provide a determination of the 20th Century (1900--2002) global sea level rise, the associated error budgets, and the quantifications of the various geophysical sources of the observed sea level rise, using data and geophysical models. We analyzed significant geographical variations of the global sea level including those caused by the steric component (heat and salinity) in the ocean, and the self-gravitational signal as a result of ice sheets melting, including the effects of glacial isostatic adjustment (GIA) since the Pleistocene. In particular, relative sea level data from long-term (longest is 150 year records) and over 600 tide gauge sites globally from PSMSL and other sources, and geocentric sea level data from multiple satellite altimetry (1985--2005) have been used to determine and characterize 20th century global sea level rise. Altimeter and selected tide gauge sea level data have been used for the 20th century sea level determination, accounting for relative biases between the altimeters, effects of sea level corresponding to oceanic thermal expansion, vertical motions affecting tide gauge measurements, self gravitations, and barotropic ocean response. This study is also characterized by the roles of the polar ocean in the global sea level study and addressing the question whether there is a detectable sea level rise acceleration during the last decade.; Vertical motions have been estimated by combining geocentric sea level measurements from satellite altimetry (TOPEX/POSEIDON) and long-term relative (crust-fixed) sea level records from global tide gauges using the Gauss-Markov (GM) model with stochastic constraints. The study provided a demonstration of improved vertical motion solutions in semi-enclosed seas and lakes, including Fennoscandia and the Great Lakes region, showing excellent agreement with independent GPS observed radial velocities, or with predictions from GIA models. In general, the estimated uncertainty of the observed vertical motion is ∼0.4 mm/yr, significantly better than other studies. Finally, improved algorithms to account for nonlinear vertical motions caused by other geodynamic processes than GIA, e.g.-post-seismic deformations, have been developed and applied to tectonically active regions such as Alaska and compared with GPS velocities and other studies. This novel technique could potentially provide improved vertical motion globally where long-term tide gauge records exist. (Abstract shortened by UMI.)...