Impact of North Atlantic Teleconnection Patterns on Northern European Sea Level

Abstract

Abstract:Northern European sea levels show a non-stationary link to the North Atlantic Oscillation (NAO). The location of the centers of the NAO dipole, however, can be affected through the interplay with the East Atlantic (EAP) and the Scandinavian (SCAN) teleconnection patterns. Our results indicate the importance of accounting for the binary combination of the NAO with the EAP/SCAN for better understanding the non-stationary drivers inducing sea level variations along the European coasts. By combining altimetry and tide gauges, we find that anomalously high monthly sea levels along the Norwegian (North Sea) coast are predominantly governed by same positive phase NAO+/EAP+ (NAO+/SCAN+) type of atmospheric circulation, while the Newlyn and Brest tide gauges respond markedly to the opposite phase NAO−/EAP+ combination. Despite these regional differences, we find that coherent European sea level changes project onto a pattern resembling NAO+/SCAN+, which is signified by pressure anomalies over Scandinavia and southern Europe forcing winds to trace the continental slope, resulting in a pile-up of water along the European coasts through Ekman transport. We conclude that taking into consideration the interaction between these atmospheric circulation regimes is valuable and may help to understand the time-varying relationship between the NAO and European mean sea level.

Multi-decadal variability in seasonal mean sea level along the North Sea coast

“…Because the sea-level response to local wind and pressure changes in the North Sea is mostly barotropic in nature (e.g. Chen et al, 2014;Dangendorf et al, 2014a), the typical sea-level adjustment timescale to wind and pressure changes will not be longer than a few days (Dimon et al, 1997). However, the sea-level response to atmospheric forcing is mostly, but not necessarily fully barotropic in the North Sea (Tsimplis et al, 2006;Calafat et al, 2012), and local and large-scale atmospheric changes do not explain all variability.…”

“…It is known that the sea-level response to local atmospheric pressure variability along the British coast often deviates from the equilibrium inverse barometer effect, which has its likely cause in factors that co-vary with atmospheric pressure, such as wind-induced surges (Woodworth et al, 2009;Woodworth, 2017b). For the German and Dutch coast, a large part of the observed sea-level variability in the winter months can be explained by the North Atlantic Oscillation (NAO) (Wakelin et al, 2003;Yan et al, 2004), which mostly acts through local wind forcing (Chen et al, 2014). The NAO contains a strong multi-decadal component, which results in multi-decadal winter-mean sea-level variability in this region (Dangendorf et al, 2012).…”

The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf

“…The SLP anomaly pattern associated with nutrient anomalies at the shelf break is best represented by a non-stationary combination of the North Atlantic Oscillation (NAO) and Scandinavian (SCAN) teleconnection patterns (Chafik et al, 2017). It also resembles the European-North Atlantic sector of the East Atlantic-west Russian pattern, a higher-order atmospheric mode of the Northern Hemisphere which occasionally mixes with the NAO (Barnston and Livezey, 1987;Fagherazzi et al, 2005).…”

“…Observational data have provided evidence for a significant increase in GIS mass loss during the recent decades (Luthcke et al, 2006;Vaughan et al, 2013;Chen, 2019). Modeling studies considered by the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC AR5) agree that the GIS will continue to decrease in area and volume in a warmer climate as a consequence of increased melting rates not compensated by increased snowfall and amplified by positive feedbacks (Mikolajewicz et al, 2007;Collins et al, 2013;Church et al, 2013;Vizcaino et al, 2015).…”

Coastal Sea Levels, Impacts, and Adaptation

“…Chafik et al [10] analyse how sea levels, observed along northern European coastlines, are affected and modulated by large-scale climate features. They detect a non-stationary sea-level response to the North Atlantic Oscillation (NAO), which is explained by the influence of the East Atlantic (EAP) and Scandinavian (SCAN) teleconnection patterns on the NAO.…”