North Sea Storminess from a Novel Storm Surge Record since AD 1843*

Abstract

The detection of potential long-term changes in historical storm statistics and storm surges plays a vitally important role for protecting coastal communities. In the absence of long homogeneous wind records, the authors present a novel, independent, and homogeneous storm surge record based on water level observations in the North Sea since 1843. Storm surges are characterized by considerable interannual-to-decadal variability linked to large-scale atmospheric circulation patterns. Time periods of increased storm surge levels prevailed in the late nineteenth and twentieth centuries without any evidence for significant long-term trends. This contradicts with recent findings based on reanalysis data, which suggest increasing storminess in the region since the late nineteenth century. The authors compare the wind and pressure fields from the Twentieth-Century Reanalysis (20CRv2) with the storm surge record by applying state-of-the-art empirical wind surge formulas. The comparison reveals that the reanalysis is a valuable tool that leads to good results over the past 100 yr; previously the statistical relationship fails, leaving significantly lower values in the upper percentiles of the predicted surge time series. These low values lead to significant upward trends over the entire investigation period, which are in turn supported by neither the storm surge record nor an independent circulation index based on homogeneous pressure readings. The authors therefore suggest that these differences are related to higher uncertainties in the earlier years of the 20CRv2 over the North Sea region.

Projections of extreme storm surge levels along Europe

“…Values for most scenarios and return periods indicate a projected increase in SSL at several locations along the North European coastline, which is more prominent for RCP8.5 and shows an increasing tendency towards the end of the century for both RCP4.5 and RCP8.5. Projected SSL changes along the European coastal areas south of 50°N show minimal change or even a small decrease, with a lack of significant trends in storminess (Dangendorf et al 2014a;Woodworth and Blackman 2002). The latter is in agreement to the conclusions of Ferreira et al (2009), who found no statistically significant increasing.…”

Observed changes and variability of atmospheric parameters in the Baltic Sea region during the last 200 years

“…WASA 1998), so that most studies rely on re analysis data or on reconstructions based on pressure observations (see Feser et al 2014 for a review). So far, pressure based reconstructions might yield more robust long-term trend analysis than reconstructions based on longterm reanalysis products over the Euro-Atlantic region since 1871 (Krueger et al 2013, Dangendorf et al 2014). The highly variable nature of precipitation with large local to regional differences together with the limited availability of data makes homogenisation of this quantity difficult.…”

Recent Change—Atmosphere

“…Lindenberg et al 2012;Wang et al 2014), but also for 20CR that to a large extent relies on these observations Krueger et al 2013;Dangendorf et al 2014;Schenk 2015). These are discussed in detail in E-Supplement S2.…”

“…They provide qualitative to semi-quantitative historical descriptions (the latter quite far back in time), such as storm surge-related damage on the Dutch coast since the 15th century (de Kraker 1999) or daily weather diaries like those at the observatory of Armagh (Ireland) since 1798 (Hickey 2003). Direct measurements such as surge levels at Liverpool since 1768 (Woodworth and Blackman 2002) and Cuxhaven since 1843 (Dangendorf et al 2014) or wind records in the Dublin region since 1715 (Sweeney 2000) also provide important information on variations in the storm climate. The difficulty with these observations is that they often represent local conditions and so often exhibit inhomogeneities to an unknown extent.…”