Nonlinear sea level trends from European tide gauge records

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Barbosa, SM (Author) FCUP; Fernandes, MJ (Author) FCUP; Silva, ME (Author) FCUP

Journal

Title: Annales Geophysicae

Vol. 22

Pages: 1465-1472

ISSN: 0992-7689

Publisher: Copernicus

Indexing

ISI Web of Knowledge - 14 Citations

Scopus - 17 Citations

Scientific classification

FOS: Natural sciences > Physical sciences

Other information

Authenticus ID: P-000-C91

Abstract (EN): Mean sea level is a variable of considerable interest in meteorological and oceanographic studies, particularly long-term sea level variation and its relation to climate changes. This study concerns the analysis of monthly mean sea level data from tide gauge stations in the Northeast Atlantic with long and continuous records. Much research effort on mean sea level studies has been focused on identifying long-term linear trends, usually estimated through least-squares fitting of a deterministic function. Here, we estimate nonparametric and robust trends using lowess, a robust smoothing procedure based on locally weighted regression. This approach is more flexible than a linear trend to describe the deterministic part of the variation in tide gauge records, which has a complex structure. A common trend pattern of reduced sea levels around 1975 is found in all the analysed records and interpreted as the result of hydrological and atmospheric forcing associated with drought conditions at the tide gauge sites. This feature is overlooked by a linear regression model. Moreover, nonlinear deterministic behaviour in the time series, such as the one identified, introduces a bias in linear trends determined from short and noisy records.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8