REGIONAL SEA-LEVEL TRENDS FROM NEARLY 20 YEARS OF RADAR ALTIMETRY

摘要

Regional sea-level trends are estimated from nearly 20 years of radar altimetry observations. Trends are estimated by taking into account the serial dependence of the data in order to obtain realistic values of the uncertainty. Furthermore, a stationarity test is applied to assess the plausibility of the linear assumption itself. The results show that most sea-level slopes are positive, indicating a general increase in sea-level at the global scale, but that the pattern of regional trends is spatially complex. Trends are not statistically significant in the eastern and central Pacific ocean and in the regions of the main current systems. Furthermore in areas of high inter-decadal variability, as in the western Pacific, sea-level long-term variability cannot be characterized by a linear trend. The present study shows that in these regions the combination of high inter-decadal variability with the still short length of the altimetric records produces spurious trends, despite large and statistically significant slopes. It is therefore of paramount importance for the quantification of regional sea-level trends to maintain the continuous operation of satellite altimeters in order to keep and extend the current altimetric record.