Long-term trends in storm surge climate derived from an ensemble of
global surge reconstructions
Abstract
We investigate trends in the magnitude and frequency of extreme storm
surge events at 320 tide gauges across the globe from 1930, 1950, and
1980 to present. We use two centennial and three satellite-era daily
storm surge time series from the Global Storm Surge Reconstructions
(GSSR) database. Before calculating trends, we perform change point
analysis to identify and remove data where inhomogeneities in
atmospheric reanalysis products could lead to spurious trends in the
storm surge data. Even after removing unreliable data, the database
still extends existing storm surge records by several decades for most
of the tide gauges. Storm surges derived from the centennial 20CR and
ERA-20C atmospheric reanalyses show consistently significant positive
trends along the southern North Sea and the Kattegat Bay regions during
the periods from 1930 and 1950 onwards and negative trends since 1980
period. When comparing all five storm surge reconstructions and
observations for the overlapping 1980-2010 period we find overall good
agreement, but distinct differences along some coastlines, such as the
Bay of Biscay and Australia. We also assess changes in the frequency of
extreme surges and find that the number of annual exceedances above the
95th percentile has increased since 1930 and 1950 in several regions
such as Western Europe, Kattegat Bay, and the US East Coast.