North Atlantic wave height trends as reconstructed from the 20th century reanalysis

Abstract

This study reports on the 1871–2010 trends in significant wave heights (Hs) in the North Atlantic, as statistically reconstructed from the 20th century reanalysis (20CR) ensemble of mean sea level pressure (SLP) fields. The 20CR SLP data set for the North Atlantic has been reported to be homogeneous since 1871, although it has discontinuities before 1949 in other regions. A multivariate regression model with lagged dependent variable is used to represent the SLP‐Hsrelationship. It is calibrated and validated using the ERA‐Interim reanalysis ofHs and SLP for the period 1981–2010.Trends in the reconstructed annual mean and maximum Hs are found to be consistent with those derived from two dynamical wave reanalysis data sets (MSC50 and ERA40), which indicates robustness of the trend estimates. The trend patterns of extreme Hsgenerally feature increases in the northeast North Atlantic with decreases in the mid‐latitudes; but there are seasonal variations. The main features of the patterns of trends over the last half century or so are also seen in the last 140‐yr period (1871–2010). However, the trend magnitudes are much greater in the last half century than in the 140 years.