Historical Sea Level in the South Pacific from Rescued Archives, Geodetic Measurements, and Satellite Altimetry

Abstract

Automatic sea-level measurements in Noumea, South Pacific, started in 1957 for the International Geophysical year. Data from this location exist in paper record for the 1957–1967 period, and in two distinct electronic records for the 1967–2005 and 2005–2015 period. In this study, we digitize the early record, and established a link between the two electronic records to create a unique, nearly 60 year-long instrumental sea-level record. This work creates one of the longest instrumental sea-level records in the Pacific Islands. These data are critical for the study of regional and interannual variations of sea level. This new data set is then used to infer rates of vertical movements by comparing it to (1) the entire satellite altimetric record (1993–2013) and (2) a global sea-level reconstruction (1957–2010). These inferred rates show an uplift of 1.3–1.4 mm/year, opposite to the currently accepted values of subsidence found in the geological and geodetic literature, and underlie the importance of systematic geodetic measurements at, over very near tide gauges.